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List of DDT Observations

Please note that obs_start_time is in UT, not local time.

Clicking on the Sequence Number link will take you to the title and abstract of the proposal.

Clicking on the ObsID link will take you to the results of our search in ADS for articles we were able to link to the ObsID. Our database extends to publications that appeared three months or more ago and does not include meeting abstracts.

A 'D' in the prop_time column means a proprietary time of 1-3 months, with the default being 3 months. A '3' means a proprietary time of three months. An 'N' means the data is public.

Click here for table only

Approved/Rejected DDT Stats from Sep 1, 2021 to Present (Sep 12, 2022)

DDTs from Sep 1, 2021 to Present (Sep 12, 2022) (Part 1)
DDTs from Sep 1, 2021 to Present (Sep 12, 2022) (Part 2)

Accepted/Approved DDT Time By Cycle from Cycle 1

Cycle	Approved Time	Requested Time
01	160	1068
02	906.5	1441
03	859.477	1982
04	468.78	989.5
05	725	1333
06	373	1090.8
07	196.6	645.4
08	1218.2	1916
09	707.2	741
10	106	2333
11	218	623
12	497	1019
13	392	803
14	427	723.1
15	440	11375
16	662.8	1119.8
17	837	1389
18	862.8	1996.8
19	646.5	1452.5
20	785.2	1645
21	1000	1481
22	767	1509
23	270	1248

DDTs from Sep 1, 2021 to Present (Sep 12, 2022)

Target Name	Category	PI	Requested Time	Approved Time	Instrument	Grating	Proprietary Time	Submission Date
SGBS J1740381-273712	BH AND NS BINARIES	Maccarone	1	1	HRC-I	NONE	N	Sep 6 2022 11:33AM
Leo I	ACTIVE GALAXIES AND QUASARS	Pacucci	80	30	ACIS-S	NONE	D	Aug 24 2022 12:40PM
GRB 220706A	SN, SNR AND ISOLATED NS	Gompertz	15	15	ACIS-S	NONE	N	Aug 9 2022 12:18PM
DQ Tau	STARS AND WD	Getman	18	18	ACIS-I	NONE	N	Jul 15 2022 4:38PM
GRB220611A	SN, SNR AND ISOLATED NS	Levan	15	15	ACIS-S	NONE	N	Jun 15 2022 10:24AM
IGRJ17091-3624	BH AND NS BINARIES	Wang	30	30	ACIS-S	HETG	D	Jun 2 2022 10:54AM
Swift J095520.7+690400.9	BH AND NS BINARIES	Brightman	10	10	ACIS-S	NONE	N	May 6 2022 1:53PM
GRB 220412B	BH AND NS BINARIES	Gompertz	40	40	ACIS-S	NONE	D	Apr 26 2022 11:11AM
Wolf 359	STARS AND WD	Howard	36	36	ACIS-S	HETG	N	Mar 22 2022 11:12PM
AT 2018hyz	ACTIVE GALAXIES AND QUASARS	Cendes	15	15	ACIS-S	NONE	D	Feb 17 2022 12:09PM
SDSS J143016.05+230344.4	ACTIVE GALAXIES AND QUASARS	Jiang	250	60	ACIS-S	NONE	1	Jan 29 2022 10:46AM
SGRB211106A	BH AND NS BINARIES	Rouco Escorial	40	40	ACIS-S	NONE	D	Dec 20 2021 12:32PM
SGRB 210726A	BH AND NS BINARIES	Schroeder	40	40	ACIS-S	NONE	D	Dec 9 2021 2:41PM
47 Tuc	BH AND NS BINARIES	Paduano	20	20	ACIS-S	NONE	N	Nov 24 2021 3:18AM
GLEAM-X J162759.5-523504.3	SN, SNR AND ISOLATED NS	Hurley-Walker	30	30	ACIS-S	NONE	D	Nov 22 2021 6:31AM
GRB210905A	SN, SNR AND ISOLATED NS	MARGUTTI	20	20	ACIS-S	NONE	N	Nov 3 2021 12:46PM
IC 10 X-1	BH AND NS BINARIES	Binder	30	30	ACIS-S	NONE	N	Oct 21 2021 4:38PM
ERO_TDE_1	ACTIVE GALAXIES AND QUASARS	Malyali	30	30	HRC-I	NONE	D	Oct 20 2021 5:38PM
SN 2021aabp	SN, SNR AND ISOLATED NS	Ho	20	20	ACIS-S	NONE	D	Oct 8 2021 10:47AM
EXO 2030+375	BH AND NS BINARIES	Pradhan	30	10	ACIS-S	HETG	D	Sep 10 2021 10:42AM

Cycle	Sequence Number	ObsID	Instrument	Grating	Approved Exposure Time	Actual Exposure Time	Target	Status	Approval Date	Start Time [UT]	Proprietary Time	PI Name

25	601707	30620	ACIS-S	NONE	20.000000	18.500000	AT2024tvd	scheduled	Nov 7 2024 9:14AM	Nov 19 2024 6:10PM	D	Yao
25	503585	30605	ACIS-S	NONE	11.000000	10.734000	DIRECTV7984M31B	observed	Oct 30 2024 1:44PM	Nov 9 2024 5:39PM	D	De
25	503585	30604	ACIS-S	NONE	17.000000	17.485806	DIRECTV7984M31B	observed	Oct 30 2024 1:44PM	Nov 8 2024 6:19PM	D	De
25	201823	30598	ACIS-S	NONE	10.000000	10.080000	EP241021a	observed	Oct 30 2024 11:14AM	Nov 4 2024 3:06AM	D	Jonker
25	201822	30590	HRC-I	NONE	45.000000	0.000000	Betelgeuse	unobserved	Oct 21 2024 5:01PM		N	O'Grady
25	503590	30581	ACIS-S	NONE	20.000000	0.000000	GRB240825A	unobserved	Oct 8 2024 8:23AM		N	Gompertz
25	503589	30580	ACIS-S	NONE	20.000000	18.944021	GRB240825A	archived	Oct 8 2024 8:23AM	Nov 12 2024 3:19PM	N	Gompertz
25	503588	30568	ACIS-S	NONE	40.000000	36.585000	AT2024wpp	archived	Oct 3 2024 9:05AM	Nov 13 2024 7:13PM	N	MARGUTTI
25	503587	30567	ACIS-S	NONE	20.000000	20.082000	AT2024wpp	archived	Oct 3 2024 9:05AM	Oct 21 2024 2:20AM	N	MARGUTTI
25	503586	30566	ACIS-S	NONE	20.000000	20.084621	AT2024wpp	archived	Oct 3 2024 9:05AM	Oct 13 2024 2:14AM	N	MARGUTTI
25	503585	30557	ACIS-S	NONE	22.000000	22.034711	DIRECTV7984M31B	observed	Sep 30 2024 9:11AM	Nov 6 2024 3:08AM	D	De
25	705195	29490	ACIS-S	HETG	22.000000	20.663821	CenA	archived	Jul 16 2024 9:27AM	Aug 7 2024 7:19AM	N	Bogensberger
25	201740	29420	ACIS-S	NONE	10.000000	10.881000	EP240414a	archived	May 16 2024 8:35AM	Jun 16 2024 5:53AM	N	Jonker
25	402525	29396	ACIS-S	NONE	10.000000	10.084704	GaiaBH3	archived	Apr 21 2024 6:14PM	May 25 2024 1:59AM	N	Pacucci
25	503516	29384	ACIS-S	NONE	15.000000	14.784000	SN2024ggi	archived	Apr 13 2024 6:00PM	Apr 27 2024 12:01AM	D	Zimmerman
25	503515	29383	ACIS-S	NONE	15.000000	15.084000	SN2024ggi	archived	Apr 13 2024 6:00PM	Apr 21 2024 4:57PM	D	Zimmerman
25	300555	29382	ACIS-S	HETG	30.000000	30.059200	V1723Sco	archived	Apr 12 2024 4:42PM	May 7 2024 7:56AM	N	Sokolovsky
25	503514	29380	ACIS-S	NONE	15.000000	16.583645	LXT240402a	archived	Apr 11 2024 6:58PM	Apr 15 2024 12:48AM	D	Troja
25	705176	29356	HRC-I	NONE	2.000000	2.002081	EP240222a	archived	Mar 26 2024 8:55AM	Apr 1 2024 2:34PM	D	Jin
25	705175	29355	ACIS-S	NONE	2.000000	2.067700	ZTF19acnskyy	archived	Mar 25 2024 9:15AM	Apr 3 2024 7:05PM	D	Hernandez-Garcia
25	201735	29353	ACIS-S	NONE	20.000000	18.786000	EP240315A	archived	Mar 17 2024 3:48PM	Mar 26 2024 4:56AM	N	Levan
25	201734	29352	ACIS-S	NONE	10.000000	10.082695	EP240315A	archived	Mar 17 2024 3:48PM	Mar 18 2024 8:13PM	N	Levan
25	402524	29351	ACIS-S	NONE	19.000000	18.383230	A0620-00	archived	Mar 15 2024 4:11PM	Mar 27 2024 9:35PM	N	Gallo
25	402524	29332	ACIS-S	NONE	17.000000	17.751000	A0620-00	archived	Mar 7 2024 1:56PM	Mar 26 2024 1:42PM	N	Gallo
25	402523	29318	HRC-I	NONE	5.000000	5.003282	SRGAJ144459.2-60420	archived	Mar 1 2024 4:30PM	Mar 6 2024 11:14AM	N	Illiano
25	503513	29317	ACIS-S	NONE	20.000000	20.080859	GRB240218A	archived	Feb 28 2024 4:01PM	Mar 4 2024 11:23PM	N	Pena
25	201730	29316	ACIS-S	HETG	10.000000	9.557300	HR1099	archived	Feb 26 2024 2:44PM	Mar 9 2024 9:32AM	N	Miller
25	201730	29315	ACIS-S	HETG	10.000000	10.059032	HR1099	archived	Feb 26 2024 2:44PM	Mar 9 2024 2:18AM	N	Miller
25	201730	29278	ACIS-S	HETG	10.000000	10.561700	HR1099	archived	Feb 6 2024 4:24PM	Mar 8 2024 6:22PM	N	Miller
24	705150	29180	ACIS-S	HETG	44.000000	42.563000	NGC4151	archived	Dec 19 2023 6:44PM	Dec 27 2023 9:45PM	D	Miller
24	705150	29179	ACIS-S	HETG	18.000000	17.612800	NGC4151	archived	Dec 19 2023 6:44PM	Dec 26 2023 12:31PM	D	Miller
24	705150	29137	ACIS-S	HETG	38.000000	37.367400	NGC4151	archived	Dec 14 2023 7:45AM	Dec 25 2023 2:06PM	D	Miller
24	705140	29072	ACIS-S	NONE	10.000000	10.093945	NGC1068	archived	Nov 7 2023 12:41PM	Jan 28 2024 5:56PM	N	Marinucci
24	705139	29071	ACIS-S	NONE	10.000000	11.094365	NGC1068	archived	Nov 7 2023 12:41PM	Jan 4 2024 5:57PM	N	Marinucci
24	705136	29069	ACIS-S	NONE	15.000000	14.483370	HE0230-2130	archived	Nov 6 2023 5:03PM	Nov 17 2023 2:07PM	N	Pooley
24	402522	29059	ACIS-S	HETG	20.000000	18.961000	CygX-3	archived	Nov 6 2023 9:10AM	Nov 22 2023 8:10PM	N	McCollough
24	705138	29040	ACIS-S	NONE	30.000000	28.086000	HE0230-2130	archived	Oct 31 2023 2:38PM	Dec 2 2023 12:31AM	N	Pooley
24	705137	29039	ACIS-S	NONE	30.000000	30.083682	HE0230-2130	archived	Oct 31 2023 2:38PM	Nov 25 2023 12:34PM	N	Pooley
24	705136	29038	ACIS-S	NONE	15.000000	14.735231	HE0230-2130	archived	Oct 31 2023 2:38PM	Nov 14 2023 4:58AM	N	Pooley
24	705135	29037	ACIS-S	NONE	30.000000	30.110455	HE0230-2130	archived	Oct 31 2023 2:38PM	Nov 8 2023 6:15PM	N	Pooley
24	503512	29036	ACIS-S	NONE	13.000000	12.166381	AT2023uqf	archived	Oct 26 2023 11:29AM	Oct 30 2023 6:26AM	D	Stein
24	503512	29035	ACIS-S	NONE	12.000000	11.730400	AT2023uqf	archived	Oct 25 2023 9:24PM	Oct 29 2023 9:11AM	D	Stein
24	402519	28927	ACIS-S	NONE	15.000000	15.091000	V404Cyg	archived	Sep 15 2023 9:47AM	Oct 14 2023 8:30PM	N	Hynes
24	402518	28925	ACIS-S	NONE	14.000000	14.074000	GRB230812B	archived	Sep 11 2023 11:55AM	Sep 23 2023 1:05AM	D	Pathak
24	402518	28868	ACIS-S	NONE	16.000000	15.074830	GRB230812B	archived	Aug 21 2023 1:06PM	Sep 18 2023 8:03PM	D	Pathak
24	402517	28867	ACIS-S	NONE	20.000000	21.675200	GRB230812B	archived	Aug 21 2023 1:06PM	Sep 3 2023 1:24AM	D	Pathak
24	503452	28374	ACIS-S	NONE	9.500000	10.019200	SN2023ixf	archived	Jul 28 2023 2:50PM	Aug 12 2023 12:28PM	D	Chandra
24	402459	28366	ACIS-S	HETG	14.000000	14.846100	4U1626-67	archived	Jul 27 2023 6:14PM	Jul 31 2023 1:33PM	N	Ng
24	402459	27960	ACIS-S	HETG	16.000000	16.547321	4U1626-67	archived	Jul 13 2023 5:56PM	Jul 31 2023 3:15AM	N	Ng
24	402459	27954	ACIS-S	HETG	30.000000	30.045062	4U1626-67	archived	Jul 7 2023 3:44PM	Jul 29 2023 3:14PM	N	Ng
24	704945	27953	ACIS-S	NONE	25.000000	23.081609	AT2021lwx	archived	Jul 6 2023 6:14PM	Nov 18 2023 3:29PM	N	Guolo
24	503453	27933	ACIS-S	NONE	20.000000	19.083000	AT2023lcr	archived	Jun 26 2023 2:51PM	Jul 3 2023 6:47AM	D	Martin-Carrillo
24	100228	27882	ACIS-S	NONE	29.900000	31.103999	LTT1445A	archived	May 26 2023 10:30AM	Aug 2 2023 11:33PM	N	Howard
24	503452	27863	ACIS-S	NONE	10.500000	11.183205	SN2023ixf	archived	May 22 2023 8:56AM	Aug 11 2023 6:38PM	D	Chandra
24	503451	27862	ACIS-S	NONE	20.000000	20.332900	SN2023ixf	archived	May 22 2023 8:56AM	May 31 2023 3:51PM	D	Chandra
24	704913	27798	ACIS-S	NONE	10.000000	10.082037	WISEAJ045649.8-2037	archived	Apr 3 2023 9:02AM	Apr 14 2023 3:51AM	D	Liu
24	402458	27779	ACIS-S	NONE	14.000000	13.783673	GRB230307A	archived	Mar 22 2023 4:23PM	Apr 2 2023 10:13AM	N	Fong
24	402458	27778	ACIS-S	NONE	17.000000	17.082000	GRB230307A	archived	Mar 22 2023 4:22PM	Apr 1 2023 9:57PM	N	Fong
24	402458	27777	ACIS-S	NONE	19.000000	20.082000	GRB230307A	archived	Mar 22 2023 10:50AM	Mar 31 2023 10:36AM	N	Fong
24	704913	27738	ACIS-S	NONE	10.000000	10.193522	WISEAJ045649.8-2037	archived	Mar 2 2023 1:47PM	Apr 11 2023 12:43AM	D	Liu
24	704912	27737	ACIS-S	NONE	10.000000	10.083000	WISEAJ045649.8-2037	archived	Mar 2 2023 1:47PM	Mar 19 2023 10:37PM	D	Liu
24	402457	27736	ACIS-S	NONE	10.000000	11.097900	Terzan5	archived	Mar 1 2023 4:58PM	Mar 18 2023 3:10PM	N	Heinke
24	402456	27707	ACIS-S	HETG	20.000000	19.916332	RXJ0440.9+4431	archived	Feb 1 2023 4:55PM	Feb 13 2023 7:36AM	D	Reynolds
23	503450	27646	ACIS-S	NONE	10.000000	10.059500	SN2022jli	archived	Dec 23 2022 10:23AM	Jan 25 2023 9:34PM	N	Chen
23	503449	27645	ACIS-S	NONE	10.000000	10.059500	SN2022jli	archived	Dec 23 2022 10:23AM	Jan 21 2023 11:00PM	N	Chen
23	503448	27644	ACIS-S	NONE	10.000000	10.062600	SN2022jli	archived	Dec 23 2022 10:23AM	Jan 17 2023 11:05AM	N	Chen
23	503444	27643	ACIS-S	NONE	16.000000	15.344835	AT2022tsd	archived	Dec 21 2022 11:47AM	Dec 29 2022 7:27AM	N	Ho
23	503444	27639	ACIS-S	NONE	24.000000	22.940584	AT2022tsd	archived	Dec 20 2022 4:41PM	Dec 26 2022 2:32PM	N	Ho
23	201611	27638	ACIS-S	NONE	20.000000	18.582000	GaiaJ1350-5914	archived	Dec 19 2022 4:18PM	Jan 25 2023 9:41AM	D	El-Badry
23	402454	27524	ACIS-S	NONE	10.000000	10.080000	GaiaBH1	archived	Oct 25 2022 12:09PM	Oct 31 2022 1:53AM	D	Rodriguez
23	901855	27517	ACIS-I	NONE	20.000000	22.031700	SwiftJ1913.1+1946	archived	Oct 12 2022 1:30PM	Oct 17 2022 5:13PM	D	Heinz
23	704875	27483	ACIS-S	NONE	10.000000	10.945828	DECALS2157-4201	archived	Oct 7 2022 10:06AM	Nov 25 2022 9:50PM	D	Pooley
23	402454	27482	ACIS-S	NONE	10.000000	9.899936	GaiaBH1	archived	Oct 5 2022 4:44PM	Oct 30 2022 5:14PM	D	Rodriguez
23	402453	27481	ACIS-S	NONE	10.000000	10.086000	NGC7793	archived	Oct 4 2022 9:07AM	Oct 27 2022 2:21PM	N	Brightman
23	704863	27480	ACIS-S	NONE	12.000000	12.569367	LeoI	archived	Oct 3 2022 3:09PM	Oct 15 2022 6:25AM	D	Pacucci
23	704871	27470	ACIS-S	NONE	3.000000	2.906434	SwiftJ023017.0+2836	archived	Sep 23 2022 9:21AM	Sep 27 2022 10:26PM	D	Evans
23	100227	27452	HRC-S	NONE	10.000000	9.914057	TIC420112589	archived	Sep 13 2022 9:49AM	Apr 10 2023 7:12AM	D	Poppenhaeger
23	402452	27444	ACIS-S	NONE	3.000000	3.097800	SwiftJ174038.1-2737	archived	Sep 9 2022 11:28AM	Oct 12 2022 2:40PM	N	Maccarone
23	704863	27442	ACIS-S	NONE	18.000000	19.240800	LeoI	archived	Sep 6 2022 4:34PM	Oct 14 2022 7:34PM	D	Pacucci
23	503440	27263	ACIS-S	NONE	15.000000	15.021000	GRB220706A	archived	Aug 10 2022 9:03AM	Aug 16 2022 1:06PM	N	Gompertz
23	201554	26475	ACIS-I	NONE	1.500000	1.602000	DQTau	archived	Jul 15 2022 5:18PM	Aug 13 2022 5:11PM	N	Getman
23	201553	26474	ACIS-I	NONE	1.500000	1.616402	DQTau	archived	Jul 15 2022 5:18PM	Aug 11 2022 5:47AM	N	Getman
23	201552	26473	ACIS-I	NONE	1.500000	1.602000	DQTau	archived	Jul 15 2022 5:18PM	Aug 10 2022 1:47PM	N	Getman
23	201551	26472	ACIS-I	NONE	1.500000	1.601909	DQTau	archived	Jul 15 2022 5:18PM	Aug 9 2022 4:22PM	N	Getman
23	201550	26471	ACIS-I	NONE	1.500000	1.572000	DQTau	archived	Jul 15 2022 5:18PM	Aug 8 2022 4:24PM	N	Getman
23	201549	26470	ACIS-I	NONE	1.500000	1.602500	DQTau	archived	Jul 15 2022 5:18PM	Aug 7 2022 1:05PM	N	Getman
23	201548	26469	ACIS-I	NONE	1.500000	1.602873	DQTau	archived	Jul 15 2022 5:18PM	Aug 6 2022 3:03PM	N	Getman
23	201547	26468	ACIS-I	NONE	1.500000	1.601858	DQTau	archived	Jul 15 2022 5:18PM	Aug 5 2022 12:20PM	N	Getman
23	201546	26467	ACIS-I	NONE	1.500000	1.601500	DQTau	archived	Jul 15 2022 5:18PM	Aug 4 2022 11:22AM	N	Getman
23	201545	26466	ACIS-I	NONE	1.500000	1.602000	DQTau	archived	Jul 15 2022 5:18PM	Aug 3 2022 5:56AM	N	Getman
23	201544	26465	ACIS-I	NONE	1.500000	1.602000	DQTau	archived	Jul 15 2022 5:18PM	Aug 2 2022 5:55AM	N	Getman
23	201543	26464	ACIS-I	NONE	1.500000	1.602989	DQTau	archived	Jul 15 2022 5:18PM	Aug 1 2022 7:31AM	N	Getman
23	503371	26441	ACIS-S	NONE	15.000000	15.080647	GRB220611A	archived	Jun 15 2022 7:22PM	Jun 23 2022 11:57PM	N	Levan
23	402361	26435	ACIS-S	HETG	30.000000	30.080045	IGRJ17091-3624	archived	Jun 2 2022 12:12PM	Jun 16 2022 11:42AM	D	Wang
23	402360	26421	ACIS-S	NONE	10.000000	10.082040	SwiftJ095520.7+6904	archived	May 11 2022 9:13AM	Jun 4 2022 11:51AM	N	Brightman
23	402359	26407	ACIS-S	NONE	40.000000	40.102883	GRB220412B	archived	Apr 27 2022 12:42PM	May 2 2022 7:25AM	D	Gompertz
23	201530	26388	ACIS-S	HETG	12.000000	11.954300	Wolf359	archived	Apr 1 2022 7:18PM	Jul 1 2022 8:05PM	N	Howard
23	201529	26387	ACIS-S	HETG	12.000000	11.950853	Wolf359	archived	Apr 1 2022 7:18PM	Jun 30 2022 7:50PM	N	Howard
23	201528	26386	ACIS-S	HETG	12.000000	11.059200	Wolf359	archived	Apr 1 2022 7:18PM	Jun 28 2022 10:49PM	N	Howard
23	704610	26350	ACIS-S	NONE	15.000000	15.080562	AT2018hyz	archived	Feb 24 2022 1:38PM	Mar 19 2022 11:12AM	D	Cendes
23	704603	26330	ACIS-S	NONE	4.000000	4.204800	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Mar 16 2022 6:02PM	1	Jiang
23	704603	26329	ACIS-S	NONE	4.000000	4.104715	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Mar 16 2022 1:23AM	1	Jiang
23	704603	26328	ACIS-S	NONE	4.000000	4.149000	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Mar 14 2022 4:11AM	1	Jiang
23	704603	26327	ACIS-S	NONE	4.000000	4.104000	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Mar 13 2022 8:17AM	1	Jiang
23	704603	26326	ACIS-S	NONE	4.000000	4.092500	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Mar 11 2022 2:49PM	1	Jiang
23	704603	26325	ACIS-S	NONE	4.000000	4.089988	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Mar 9 2022 1:12PM	1	Jiang
23	704603	26324	ACIS-S	NONE	4.000000	4.091500	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Mar 7 2022 11:50PM	1	Jiang
23	704603	26323	ACIS-S	NONE	4.000000	4.090758	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Mar 6 2022 10:09AM	1	Jiang
23	704603	26322	ACIS-S	NONE	4.000000	4.091000	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Mar 3 2022 11:01PM	1	Jiang
23	704603	26321	ACIS-S	NONE	4.000000	4.091870	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Mar 2 2022 9:54AM	1	Jiang
23	704603	26320	ACIS-S	NONE	4.000000	4.092000	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Feb 28 2022 9:51PM	1	Jiang
23	704603	26319	ACIS-S	NONE	4.000000	4.091383	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Feb 27 2022 7:31AM	1	Jiang
23	704603	26318	ACIS-S	NONE	4.000000	4.091000	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Feb 25 2022 4:13AM	1	Jiang
23	704603	26317	ACIS-S	NONE	4.000000	4.091500	SDSSJ143016.05+2303	archived	Feb 7 2022 3:41PM	Feb 23 2022 1:27AM	1	Jiang
23	704603	26316	ACIS-S	NONE	4.000000	4.090000	SDSSJ143016.05+2303	archived	Feb 7 2022 2:39PM	Feb 21 2022 3:46AM	1	Jiang
22	402355	26286	ACIS-S	NONE	10.000000	9.959991	47Tuc	archived	Jan 14 2022 12:19PM	Jan 27 2022 2:32AM	N	Paduano
22	503370	26282	ACIS-S	NONE	10.000000	10.111420	GLEAM-XJ162759.5-52	archived	Jan 10 2022 12:17PM	Jan 23 2022 6:25AM	D	Hurley-Walker
22	402357	26262	ACIS-S	NONE	19.000000	18.463645	SGRB211106A	archived	Dec 21 2021 12:13PM	Jan 5 2022 3:49AM	D	RoucoEscorial
22	402357	26249	ACIS-S	NONE	21.000000	19.962000	SGRB211106A	archived	Dec 20 2021 12:41PM	Jan 4 2022 3:21PM	D	RoucoEscorial
22	402356	26247	ACIS-S	NONE	40.000000	36.753000	SGRB210726A	archived	Dec 13 2021 10:50AM	Dec 31 2021 7:10PM	D	Schroeder
22	402355	26229	ACIS-S	NONE	10.000000	9.780000	47Tuc	archived	Dec 6 2021 9:08AM	Jan 26 2022 3:48PM	N	Paduano
22	503370	26228	ACIS-S	NONE	20.000000	20.090522	GLEAM-XJ162759.5-52	archived	Nov 26 2021 1:53PM	Jan 22 2022 9:13PM	D	Hurley-Walker
22	503369	26205	ACIS-S	NONE	20.000000	19.409637	GRB210905A	archived	Nov 4 2021 12:17PM	Nov 24 2021 1:28PM	N	MARGUTTI
22	704586	26189	HRC-I	NONE	30.000000	30.123471	ERO_TDE_1	archived	Oct 28 2021 11:41AM	Nov 10 2021 11:50PM	D	Malyali
22	402354	26188	ACIS-S	NONE	30.000000	30.073100	IC10X-1	archived	Oct 28 2021 11:04AM	Jan 7 2022 6:26AM	N	Binder
22	503368	26159	ACIS-S	NONE	20.000000	19.889600	SN2021aabp	archived	Oct 8 2021 12:28PM	Oct 15 2021 8:05AM	D	Ho
22	402353	26154	ACIS-S	HETG	10.000000	10.080000	EXO2030+375	archived	Sep 30 2021 5:15PM	Oct 20 2021 3:43AM	D	Pradhan
22	503296	25093	ACIS-S	NONE	20.000000	20.090218	GRB210704A	archived	Jul 13 2021 9:05AM	Jul 19 2021 1:50AM	D	Troja
22	300502	25092	HRC-S	LETG	30.000000	30.040830	V1674Her	archived	Jul 12 2021 9:04AM	Jul 19 2021 7:59AM	N	Drake
22	300501	25089	HRC-S	NONE	10.000000	10.134432	TCPJ18573095+165339	archived	Jul 3 2021 5:11PM	Jul 10 2021 1:30AM	N	Maccarone
22	402298	25079	ACIS-S	HETG	30.000000	28.058000	4U1543-475	archived	Jun 13 2021 1:38PM	Jun 21 2021 9:23AM	N	Miller
22	503295	25064	ACIS-S	NONE	19.000000	18.288000	AT2020mrf	archived	Jun 7 2021 11:20AM	Jun 19 2021 8:21AM	N	Yao
22	402296	25063	ACIS-S	HETG	12.500000	12.625000	MAXIJ1803-298	archived	Jun 7 2021 11:19AM	Jun 18 2021 5:21AM	D	DiazTrigo
22	704293	25060	HRC-S	LETG	28.000000	28.038000	AT2019avd	archived	Jun 2 2021 12:05PM	Jun 9 2021 8:08PM	N	Pasham
22	704293	25056	HRC-S	LETG	22.000000	21.877601	AT2019avd	archived	May 31 2021 3:16PM	Jun 8 2021 4:49PM	N	Pasham
22	402297	25054	ACIS-S	NONE	30.000000	29.947334	MAXIJ1348-630	archived	May 14 2021 4:32PM	Jun 28 2021 6:01AM	D	Carotenuto
22	503295	25050	ACIS-S	NONE	21.000000	20.091000	AT2020mrf	archived	May 13 2021 10:36AM	Jun 18 2021 10:29AM	N	Yao
22	503294	25049	ACIS-S	NONE	60.000000	60.053200	CXOJ134856.4+263944	archived	May 12 2021 9:33AM	Jun 2 2021 11:43PM	D	Lin
22	402296	25041	ACIS-S	HETG	12.500000	12.627000	MAXIJ1803-298	archived	May 10 2021 11:29AM	Jun 17 2021 8:29PM	D	DiazTrigo
22	402295	25040	ACIS-S	HETG	25.000000	23.700000	MAXIJ1803-298	archived	May 10 2021 11:29AM	May 23 2021 7:30PM	D	DiazTrigo
22	402294	25039	ACIS-S	HETG	25.000000	25.100000	MAXIJ1803-298	archived	May 10 2021 11:29AM	May 17 2021 9:15AM	D	DiazTrigo
22	704292	25025	ACIS-S	HETG	50.000000	50.079943	NGC4151	archived	Apr 23 2021 9:46AM	May 3 2021 10:37AM	D	Miller
22	503293	25016	ACIS-S	NONE	30.000000	30.066227	FRB20201124A	archived	Apr 16 2021 12:40PM	Apr 20 2021 5:28AM	D	Piro
22	503292	25005	HRC-I	NONE	2.000000	2.180175	ASASSN-20hx	archived	Mar 30 2021 2:15PM	Apr 16 2021 7:35AM	N	Mandal
22	402293	24986	ACIS-S	NONE	10.000000	10.091968	SwiftJ130456-493158	archived	Mar 4 2021 2:05PM	Mar 10 2021 4:06AM	N	Brightman
22	503291	24966	ACIS-S	NONE	25.000000	25.070248	ASKAPJ173608.2-3216	archived	Feb 12 2021 11:16AM	Feb 17 2021 2:51PM	N	Kaplan
22	503290	24965	ACIS-S	NONE	25.000000	24.590441	GRB190610A	archived	Feb 8 2021 10:52AM	Feb 26 2021 7:53AM	N	Tohuvavohu
21	704287	24911	ACIS-S	NONE	15.000000	15.069599	PKS1127-14	archived	Dec 18 2020 9:28AM	Jan 1 2021 7:34PM	D	Siemiginowska
21	503289	24910	ACIS-S	NONE	25.000000	25.317039	GRB201214B	archived	Dec 16 2020 5:27PM	Jan 11 2021 2:29PM	D	Troja
21	503288	24909	ACIS-S	NONE	25.000000	25.054200	GRB201214B	archived	Dec 16 2020 5:27PM	Dec 22 2020 5:35PM	D	Troja
21	704286	24876	ACIS-S	NONE	30.000000	29.059377	ESO253-G003	archived	Nov 18 2020 2:02PM	Jan 21 2021 8:11PM	D	Payne
21	704285	24875	ACIS-S	NONE	30.000000	28.061200	ESO253-G003	archived	Nov 18 2020 2:02PM	Dec 26 2020 12:11PM	D	Payne
21	100204	24847	HRC-I	NONE	10.000000	10.006307	Saturn	archived	Oct 19 2020 8:53AM	Nov 23 2020 11:01PM	N	Weigt
21	100204	24846	HRC-I	NONE	10.000000	10.136482	Saturn	archived	Oct 19 2020 8:53AM	Nov 21 2020 12:31PM	N	Weigt
21	100204	24845	HRC-I	NONE	10.000000	10.125976	Saturn	archived	Oct 19 2020 8:46AM	Nov 19 2020 11:48AM	N	Weigt
21	503287	24841	ACIS-S	NONE	5.000000	5.078000	SGR1830-0645	archived	Oct 10 2020 4:38PM	Oct 13 2020 9:51PM	N	Kouveliotou
21	704283	24755	ACIS-S	NONE	30.000000	30.060798	RXJ1756.4+5235	archived	Sep 28 2020 3:41AM	Nov 5 2020 4:02AM	N	Koss
21	704254	24667	ACIS-S	HETG	23.000000	22.639115	Mrk279	archived	Sep 21 2020 4:16PM	Oct 3 2020 4:09AM	D	Miller
21	704254	24666	ACIS-S	HETG	23.000000	22.943727	Mrk279	archived	Sep 21 2020 4:16PM	Sep 30 2020 8:08AM	D	Miller
21	704254	24665	ACIS-S	HETG	23.000000	22.943436	Mrk279	archived	Sep 21 2020 4:16PM	Sep 29 2020 1:43PM	D	Miller
21	704254	24662	ACIS-S	HETG	31.000000	31.884800	Mrk279	archived	Sep 16 2020 7:18AM	Sep 28 2020 4:18PM	D	Miller
21	402282	24651	ACIS-S	HETG	25.000000	25.070399	AT2019wey/SRG	archived	Sep 9 2020 12:18PM	Sep 20 2020 5:59PM	N	Kulkarni
21	704251	24640	ACIS-S	NONE	20.000000	20.056783	2MASXJ01110461-4558	archived	Aug 24 2020 5:43AM	Sep 16 2020 4:12PM	D	Lin
21	503278	24619	ACIS-S	NONE	30.000000	30.054932	PSRJ1846-0258	archived	Aug 13 2020 3:35PM	Sep 15 2020 10:39AM	N	Blumer
21	402198	23360	ACIS-S	HETG	15.000000	15.078000	herculesx-1	archived	Jul 31 2020 9:39AM	Aug 14 2020 10:05PM	D	Kosec
21	402198	23356	ACIS-S	HETG	35.000000	35.077750	herculesx-1	archived	Jul 20 2020 9:03AM	Aug 12 2020 5:43AM	D	Kosec
21	503207	23331	ACIS-S	NONE	10.000000	10.092000	SN2012au	archived	Jul 9 2020 1:37PM	Jul 20 2020 8:08AM	D	MARGUTTI
21	503207	23316	ACIS-S	NONE	10.000000	9.912000	SN2012au	archived	Jun 30 2020 3:19PM	Jul 19 2020 5:05PM	D	MARGUTTI
21	503206	23315	ACIS-S	NONE	12.000000	12.356394	SN2020nlb	archived	Jun 30 2020 10:17AM	Jul 12 2020 4:34AM	D	Sand
21	503206	23314	ACIS-S	NONE	63.000000	62.680954	SN2020nlb	archived	Jun 29 2020 3:06PM	Jul 10 2020 12:16AM	D	Sand
21	704049	23300	ACIS-S	HETG	30.000000	30.077106	Mrk335	archived	Jun 22 2020 12:38PM	Jul 4 2020 2:17AM	N	Boissay-Malaquin
21	704049	23299	ACIS-S	HETG	30.000000	30.079173	Mrk335	archived	Jun 22 2020 12:38PM	Jul 3 2020 8:29AM	N	Boissay-Malaquin
21	704049	23298	ACIS-S	HETG	30.000000	30.079257	Mrk335	archived	Jun 22 2020 12:38PM	Jul 2 2020 2:15AM	N	Boissay-Malaquin
21	704049	23297	ACIS-S	HETG	30.000000	30.076502	Mrk335	archived	Jun 22 2020 12:38PM	Jul 1 2020 9:25AM	N	Boissay-Malaquin
21	704049	23292	ACIS-S	HETG	30.000000	30.080000	Mrk335	archived	Jun 19 2020 5:44PM	Jun 30 2020 4:41PM	N	Boissay-Malaquin
21	704048	23289	ACIS-S	NONE	50.000000	47.409000	AT2018fyk	archived	Jun 16 2020 10:25AM	Jun 29 2020 5:34AM	N	Wevers
21	503205	23285	ACIS-S	NONE	20.000000	19.962000	GRB190829A	archived	Jun 11 2020 11:03AM	Jun 29 2020 7:15PM	D	Troja
21	402197	23266	ACIS-S	NONE	30.000000	30.092837	NGC7793P13	archived	May 11 2020 9:42AM	Jun 4 2020 4:57PM	N	Walton
21	503204	23251	ACIS-S	NONE	20.000000	19.061460	SGRJ1935+2154	archived	May 6 2020 2:50PM	May 18 2020 11:04AM	D	Gogus
21	100193	23232	HRC-S	LETG	3.300000	3.492431	C/2019Y4ATLAS	archived	Apr 13 2020 2:44PM	Apr 28 2020 7:59PM	D	Bodewits
21	100193	23231	HRC-S	LETG	3.300000	3.494481	C/2019Y4ATLAS	archived	Apr 13 2020 2:44PM	Apr 28 2020 6:56PM	D	Bodewits
21	100193	23230	HRC-S	LETG	3.300000	3.494481	C/2019Y4ATLAS	archived	Apr 13 2020 2:44PM	Apr 28 2020 5:52PM	D	Bodewits
21	100193	23229	HRC-S	LETG	3.300000	3.496531	C/2019Y4ATLAS	archived	Apr 13 2020 2:44PM	Apr 28 2020 4:49PM	D	Bodewits
21	100193	23228	HRC-S	LETG	3.300000	3.492431	C/2019Y4ATLAS	archived	Apr 13 2020 2:44PM	Apr 28 2020 3:45PM	D	Bodewits
21	100193	23227	HRC-S	LETG	3.300000	3.494481	C/2019Y4ATLAS	archived	Apr 13 2020 2:44PM	Apr 28 2020 2:42PM	D	Bodewits
21	100193	23226	HRC-S	LETG	3.300000	3.490125	C/2019Y4ATLAS	archived	Apr 13 2020 2:44PM	Apr 28 2020 1:38PM	D	Bodewits
21	100193	23225	HRC-S	LETG	3.300000	3.496531	C/2019Y4ATLAS	archived	Apr 13 2020 2:44PM	Apr 28 2020 12:35PM	D	Bodewits
21	100193	23224	HRC-S	LETG	3.600000	3.641056	C/2019Y4ATLAS	archived	Apr 10 2020 5:52PM	Apr 28 2020 11:26AM	D	Bodewits
21	503203	23209	ACIS-S	NONE	30.000000	30.059561	J1818-1607	archived	Mar 24 2020 1:50PM	Apr 3 2020 5:48AM	D	Blumer
21	300469	23179	ACIS-S	NONE	25.000000	23.376000	Haro1-10	archived	Feb 19 2020 1:52PM	Jun 8 2020 5:13PM	D	Lucy
21	300468	23178	ACIS-S	NONE	10.000000	9.849000	IRAS15175-4508	archived	Feb 19 2020 1:52PM	May 18 2020 5:30PM	D	Lucy
21	503202	23172	ACIS-S	NONE	10.000000	10.050200	SN2020bvc	archived	Feb 12 2020 5:07PM	Feb 29 2020 2:15AM	N	Ho
21	503201	23171	ACIS-S	NONE	10.000000	10.055784	SN2020bvc	archived	Feb 12 2020 5:07PM	Feb 16 2020 8:31PM	N	Ho
21	201344	23148	HRC-I	NONE	5.000000	5.042232	Betelgeuse	archived	Jan 29 2020 3:26PM	Aug 15 2020 11:56AM	N	Kashyap
21	201343	23147	HRC-I	NONE	5.000000	5.159850	Betelgeuse	archived	Jan 29 2020 3:26PM	Feb 17 2020 7:32PM	N	Kashyap
21	503200	23141	ACIS-S	NONE	10.000000	10.090736	SN2020oi	archived	Jan 21 2020 2:09PM	Mar 13 2020 9:53AM	D	Stroh
21	503199	23140	ACIS-S	NONE	10.000000	10.090829	SN2020oi	archived	Jan 21 2020 2:09PM	Feb 15 2020 1:25AM	D	Stroh
21	503198	23133	ACIS-S	NONE	10.000000	10.058177	SN2019yvq	archived	Jan 17 2020 10:42AM	Feb 6 2020 6:16AM	N	Pooley
21	704036	23132	ACIS-S	NONE	5.000000	5.111237	SDSSJ1539+3954	archived	Jan 17 2020 10:38AM	Jun 18 2020 12:11AM	N	Ni
20	402196	23116	ACIS-S	NONE	15.000000	15.056700	4FGLJ0336.0+7502	archived	Dec 18 2019 2:37PM	Jan 25 2020 12:00PM	N	Li
20	300467	23108	ACIS-S	NONE	50.000000	48.112000	RAqr	archived	Dec 12 2019 4:50PM	Jan 12 2020 12:13AM	3	Karovska
20	704032	23107	ACIS-S	NONE	25.000000	27.053700	PSOJ047.4479+27.299	archived	Dec 12 2019 1:34PM	Mar 24 2020 8:50PM	N	moretti
20	402195	23106	ACIS-S	NONE	10.000000	9.945600	NGC4045	archived	Dec 10 2019 3:28PM	Dec 31 2019 6:11AM	N	Brightman
20	100192	23093	HRC-S	NONE	12.500000	12.688476	C/2019Q4Borisov	archived	Nov 27 2019 12:58PM	Dec 18 2019 6:49PM	N	Snios
20	100192	23092	HRC-S	NONE	12.500000	12.662082	C/2019Q4Borisov	archived	Nov 27 2019 12:58PM	Dec 18 2019 3:12PM	N	Snios
20	100192	23091	HRC-S	NONE	12.500000	12.690782	C/2019Q4Borisov	archived	Nov 27 2019 12:58PM	Dec 17 2019 1:39AM	N	Snios
20	100192	23090	HRC-S	NONE	12.500000	12.655932	C/2019Q4Borisov	archived	Nov 27 2019 12:58PM	Dec 16 2019 10:02PM	N	Snios
20	100192	23089	HRC-S	NONE	12.500000	12.694882	C/2019Q4Borisov	archived	Nov 27 2019 12:58PM	Dec 16 2019 8:02AM	N	Snios
20	503197	23082	ACIS-S	NONE	18.000000	17.971999	FRB180916.J0158+65	archived	Nov 13 2019 4:46PM	Dec 18 2019 4:01AM	D	Scholz
20	503197	23081	ACIS-S	NONE	18.000000	18.070654	FRB180916.J0158+65	archived	Nov 13 2019 4:25PM	Dec 3 2019 1:46AM	D	Scholz
20	100192	22919	HRC-S	NONE	12.500000	12.534982	C/2019Q4Borisov	archived	Oct 22 2019 3:16PM	Dec 16 2019 4:25AM	N	Snios
20	704028	22918	ACIS-S	NONE	4.000000	4.062914	PKS1413+135	archived	Oct 18 2019 9:57AM	Jun 18 2020 11:00PM	N	Liodakis
20	704028	22917	ACIS-S	NONE	4.000000	4.063425	PKS1413+135	archived	Oct 18 2019 9:57AM	May 4 2020 12:19AM	N	Liodakis
20	704028	22916	ACIS-S	NONE	4.000000	4.061000	PKS1413+135	archived	Oct 18 2019 9:57AM	Mar 22 2020 5:28AM	N	Liodakis
20	704028	22915	ACIS-S	NONE	4.000000	4.057900	PKS1413+135	archived	Oct 18 2019 9:57AM	Feb 3 2020 6:10PM	N	Liodakis
20	704028	22914	ACIS-S	NONE	4.000000	4.064100	PKS1413+135	archived	Oct 18 2019 9:13AM	Dec 20 2019 11:30PM	N	Liodakis
20	100191	22913	ACIS-S	NONE	1.000000	1.048585	V1298Tau	archived	Oct 17 2019 8:23PM	Nov 17 2019 2:54PM	N	Poppenhaeger
20	402194	22886	ACIS-S	HETG	30.000000	30.084319	GRS1915+105	archived	Oct 11 2019 4:19PM	Nov 30 2019 9:04AM	D	Miller
20	402193	22885	ACIS-S	HETG	30.000000	30.044101	GRS1915+105	archived	Oct 11 2019 4:19PM	Nov 3 2019 9:08AM	D	Miller
20	503196	22848	ACIS-S	NONE	20.000000	20.090037	AT2019osy	archived	Sep 6 2019 2:00PM	Sep 22 2019 9:33PM	N	Jaodand
20	300466	22845	ACIS-S	HETG	30.000000	29.948800	V3890Sgr	archived	Aug 29 2019 3:41PM	Sep 3 2019 7:29AM	N	Orio
20	300465	22682	ACIS-S	NONE	15.000000	15.082639	V1369Cen	archived	Jul 29 2019 11:01AM	Sep 2 2019 3:00AM	D	Drake
20	402123	22289	ACIS-S	NONE	30.000000	30.070602	SwiftJ1728.9-3613	archived	Jul 16 2019 11:35AM	Jul 28 2019 5:19AM	D	Miller
20	402122	22285	ACIS-S	NONE	10.000000	9.558000	4U1901+03	archived	Jul 9 2019 1:45PM	Jul 14 2019 7:41AM	N	Lutovinov
20	402121	22277	ACIS-S	HETG	25.000000	26.652000	4U1820-30	archived	Jul 3 2019 1:55PM	Jul 8 2019 1:09PM	N	Heinke
20	402121	22276	ACIS-S	HETG	25.000000	26.909000	4U1820-30	archived	Jul 3 2019 11:35AM	Jul 7 2019 5:22PM	N	Heinke
20	503149	22271	ACIS-S	NONE	15.000000	15.091639	SN2003gk	archived	Jun 17 2019 10:22AM	Aug 5 2019 3:47PM	N	Patnaude
20	703897	22240	ACIS-S	HETG	10.000000	10.069509	PKS1830-211	archived	May 22 2019 1:06PM	Jun 16 2019 4:22PM	D	Buson
20	703896	22239	ACIS-S	HETG	10.000000	10.070393	PKS1830-211	archived	May 22 2019 1:06PM	Jun 15 2019 10:43PM	D	Buson
20	402117	22213	ACIS-S	HETG	30.000000	30.078001	GRS1915+105	archived	Apr 25 2019 11:45AM	Apr 30 2019 4:49AM	D	Miller
20	703892	22212	ACIS-S	NONE	20.000000	20.082000	SDSSJ085051.98+0830	archived	Apr 22 2019 2:33PM	May 12 2019 6:37PM	N	Civano
20	703887	22199	ACIS-S	HETG	25.000000	25.995974	PKS1830-211	archived	Apr 15 2019 12:45PM	May 24 2019 8:25PM	N	Buson
20	703886	22198	ACIS-S	HETG	20.000000	20.069181	PKS1830-211	archived	Apr 15 2019 12:45PM	May 7 2019 12:51PM	N	Buson
20	703885	22197	ACIS-S	HETG	15.000000	14.069199	PKS1830-211	archived	Apr 15 2019 12:45PM	Apr 19 2019 7:16AM	N	Buson
20	201266	22186	ACIS-S	HETG	12.600000	12.647713	ProximaCentauri	archived	Apr 8 2019 4:41PM	May 6 2019 4:05AM	D	MacGregor
20	201265	22185	ACIS-S	HETG	12.600000	13.062752	ProximaCentauri	archived	Apr 8 2019 4:41PM	May 3 2019 3:58AM	D	MacGregor
20	703879	22183	ACIS-S	NONE	10.000000	10.108726	NAMEAT2019ahk	archived	Apr 5 2019 11:22AM	Jun 9 2019 12:47AM	D	Alexander
20	703878	22182	ACIS-S	NONE	10.000000	10.109100	NAMEAT2019ahk	archived	Apr 5 2019 11:22AM	Apr 17 2019 12:57PM	D	Alexander
20	100182	22159	HRC-I	NONE	36.000000	36.101783	Jupiter	archived	Mar 12 2019 6:23PM	May 29 2019 3:43AM	N	Gladstone
20	402115	22134	HRC-I	NONE	2.000000	2.182481	4U1901+03	archived	Feb 14 2019 5:10PM	Mar 5 2019 5:57PM	N	Hemphill
20	703863	22096	ACIS-S	NONE	80.000000	73.566101	GSN069	archived	Jan 31 2019 12:33PM	Feb 14 2019 4:52PM	D	Miniutti
20	402114	22095	ACIS-S	NONE	15.000000	15.090000	SXP4.78	archived	Jan 30 2019 4:59PM	Mar 1 2019 1:20AM	N	Lutovinov
19	703841	22021	ACIS-S	NONE	1.500000	1.426000	[SDK2021]GraLJ1817	archived	Nov 30 2018 11:42AM	May 30 2019 3:06AM	D	Pooley
19	703840	22020	ACIS-S	NONE	1.500000	1.612000	[LAM2018]J1721+8842	archived	Nov 30 2018 11:42AM	May 30 2019 2:12AM	D	Pooley
19	703839	22019	ACIS-S	NONE	1.500000	1.592900	[SDK2021]GraLJ1537	archived	Nov 30 2018 11:42AM	May 11 2019 7:53AM	D	Pooley
19	703838	22018	ACIS-S	NONE	1.500000	1.692600	[SDK2021]GraLJ0659	archived	Nov 30 2018 11:42AM	Jan 15 2019 2:26PM	D	Pooley
19	703837	22017	ACIS-S	NONE	1.500000	1.608900	[SMC2017]WISEJ2344	archived	Nov 30 2018 11:42AM	Apr 16 2019 3:38AM	D	Pooley
19	703836	22016	ACIS-S	NONE	1.500000	1.610558	SDSSJ1251+2935	archived	Nov 30 2018 11:42AM	Mar 16 2019 6:21AM	D	Pooley
19	703835	22015	ACIS-S	NONE	1.500000	1.608770	DESJ0420-4037	archived	Nov 30 2018 11:42AM	May 10 2019 9:35PM	D	Pooley
19	703834	22014	ACIS-S	NONE	1.500000	1.612000	DESJ040559.80-33085	archived	Nov 30 2018 11:42AM	May 13 2019 12:46AM	D	Pooley
19	703833	22013	ACIS-S	NONE	1.500000	1.608679	DESJ0029-3814	archived	Nov 30 2018 11:42AM	Jan 29 2019 10:08AM	D	Pooley
19	201264	22012	ACIS-S	NONE	20.000000	19.064912	HD60848	archived	Nov 30 2018 11:26AM	Dec 30 2018 1:30AM	D	Rauw
19	402113	21868	ACIS-S	NONE	20.000000	19.948800	GS1354-64	archived	Sep 26 2018 4:18PM	Oct 8 2018 6:22AM	D	Reynolds
19	402112	21866	ACIS-S	NONE	3.000000	3.090700	[OBM2019]ESO338-4	archived	Sep 21 2018 3:35PM	Nov 19 2018 1:39AM	D	Oskinova
19	201263	21855	ACIS-S	NONE	20.000000	20.171700	2MASSJ05351918-0518	archived	Sep 7 2018 5:24PM	Dec 11 2018 11:29PM	N	Cleeves
19	201262	21854	ACIS-S	NONE	20.000000	20.058950	2MASSJ05351918-0518	archived	Sep 7 2018 5:24PM	Dec 5 2018 10:50AM	N	Cleeves
19	703832	21732	ACIS-S	NONE	10.000000	10.062600	TXS2116-077	archived	Aug 20 2018 10:29AM	Sep 15 2018 8:42AM	D	Paliya
19	300461	21671	HRC-S	LETG	10.000000	9.766457	VWHyi	archived	Aug 5 2018 2:13PM	Aug 8 2018 12:29AM	N	Knigge
19	503140	21660	ACIS-S	NONE	20.000000	20.088000	SN2012au	archived	Jul 17 2018 3:50PM	Aug 2 2018 1:57PM	D	Patnaude
19	503053	21122	HRC-S	LETG	50.000000	47.288378	SN2018cow	archived	Jun 21 2018 1:05PM	Jun 24 2018 3:21PM	N	Maccarone
19	201206	21102	HRC-I	NONE	30.000000	30.146533	ALPHABOO	archived	May 24 2018 9:20AM	Jun 10 2018 7:57PM	S	AYRES
19	703679	21097	ACIS-S	NONE	10.000000	10.080000	SDSSJ110731.23+1347	archived	May 9 2018 8:55AM	Jun 14 2018 3:47AM	N	Chilingarian
19	703678	21091	ACIS-S	NONE	10.000000	10.074876	NGC3893	archived	Apr 19 2018 3:33PM	Jun 28 2018 11:41AM	N	McHardy
19	402025	21090	ACIS-S	NONE	47.000000	46.610473	GW170817	archived	Apr 18 2018 3:51PM	May 5 2018 1:25AM	N	Wilkes
19	402026	21083	ACIS-S	HETG	30.000000	30.079042	SwiftJ1658.2-4242	archived	Apr 16 2018 1:48PM	Apr 28 2018 1:26AM	D	Ponti
19	503043	21082	ACIS-S	NONE	23.000000	23.091000	SN2011ja	archived	Apr 11 2018 3:00PM	Dec 6 2018 1:03AM	S	Patnaude
19	402025	21080	ACIS-S	NONE	53.000000	51.456900	GW170817	archived	Apr 11 2018 9:41AM	May 3 2018 10:41AM	N	Wilkes
19	703677	21076	ACIS-S	NONE	10.000000	9.972748	M87	archived	Apr 2 2018 9:13PM	Apr 24 2018 1:48PM	N	Wong
19	703676	21075	ACIS-S	NONE	10.000000	10.069495	M87	archived	Apr 2 2018 9:13PM	Apr 22 2018 12:19AM	N	Wong
19	703675	21058	HRC-I	NONE	15.000000	14.779732	3C264	archived	Mar 20 2018 11:20AM	Apr 4 2018 7:08PM	N	Santander
19	503052	21040	ACIS-S	NONE	20.000000	20.050800	iPTF14hls	archived	Mar 6 2018 7:18AM	Apr 4 2018 1:10PM	D	MARGUTTI
19	703674	21033	ACIS-S	NONE	11.300000	11.352200	UGC416	archived	Feb 26 2018 12:39PM	Sep 9 2018 3:35PM	S	Gallo
19	703673	21032	ACIS-S	NONE	9.600000	9.653400	LSBCF570-05	archived	Feb 26 2018 12:39PM	Jun 28 2018 8:36AM	S	Gallo
19	703672	21031	ACIS-S	NONE	8.400000	8.474345	UGC11578	archived	Feb 26 2018 12:39PM	Aug 5 2018 12:06PM	S	Gallo
19	703671	21030	ACIS-S	NONE	7.800000	7.852300	UGC10015	archived	Feb 26 2018 12:39PM	May 7 2018 9:09PM	S	Gallo
19	703670	21029	ACIS-S	NONE	7.700000	7.963900	UGC10017	archived	Feb 26 2018 12:39PM	May 17 2018 3:52AM	S	Gallo
19	703669	21028	ACIS-S	NONE	7.400000	7.650720	UGC09927	archived	Feb 26 2018 12:39PM	May 6 2018 2:56PM	S	Gallo
19	703668	21027	ACIS-S	NONE	6.900000	6.792100	UGC05750	archived	Feb 26 2018 12:39PM	Mar 21 2018 12:17PM	S	Gallo
19	703667	21026	ACIS-S	NONE	6.700000	6.754900	UGC04669	archived	Feb 26 2018 12:39PM	May 23 2018 9:51PM	S	Gallo
19	703666	21025	ACIS-S	NONE	5.800000	5.691445	UGC1230	archived	Feb 26 2018 12:39PM	Nov 14 2018 5:50AM	S	Gallo
19	703665	21024	ACIS-S	NONE	5.800000	5.852800	UGC05005	archived	Feb 26 2018 12:39PM	Jun 19 2018 4:26PM	S	Gallo
19	703664	21023	ACIS-S	NONE	15.600000	15.070960	LSBCF583-04	archived	Feb 26 2018 12:39PM	May 24 2018 9:33PM	S	Gallo
19	703663	21022	ACIS-S	NONE	12.600000	12.654111	LSBCF576-01	archived	Feb 26 2018 12:39PM	Aug 13 2018 11:20AM	S	Gallo
19	703662	21021	ACIS-S	NONE	10.400000	10.450100	LSBCF743-01	archived	Feb 26 2018 12:39PM	Sep 2 2018 7:07AM	S	Gallo
19	703661	21020	ACIS-S	NONE	7.100000	7.154491	LSBCF612-01	archived	Feb 26 2018 12:39PM	Sep 24 2018 8:47PM	S	Gallo
19	703660	21019	ACIS-S	NONE	6.500000	6.553400	LSBCF544-01	archived	Feb 26 2018 12:39PM	Nov 14 2018 3:44AM	S	Gallo
19	703659	21018	ACIS-S	NONE	6.400000	6.451100	UGC09024	archived	Feb 26 2018 12:39PM	Apr 4 2018 3:50AM	S	Gallo
19	703658	21017	ACIS-S	NONE	9.000000	9.048900	LSBCF750-04	archived	Feb 26 2018 12:39PM	Aug 26 2018 11:56PM	S	Gallo
19	703657	21016	ACIS-S	NONE	7.400000	7.449300	IC3605	archived	Feb 26 2018 12:39PM	Apr 3 2018 2:35PM	S	Gallo
19	703656	21015	ACIS-S	NONE	7.100000	6.990500	UGC06151	archived	Feb 26 2018 12:39PM	Mar 21 2018 10:03AM	S	Gallo
19	703655	21014	ACIS-S	NONE	6.700000	6.742500	LSBCF570-06	archived	Feb 26 2018 12:39PM	Nov 25 2018 11:32AM	S	Gallo
19	703654	21013	ACIS-S	NONE	6.100000	6.150214	UGC05629	archived	Feb 26 2018 12:39PM	Jul 2 2018 8:59PM	S	Gallo
19	703653	21012	ACIS-S	NONE	5.900000	5.952000	LSBCF574-09	archived	Feb 26 2018 12:39PM	Apr 14 2018 10:37AM	S	Gallo
19	703652	21011	ACIS-S	NONE	4.800000	4.854437	UGC05675	archived	Feb 26 2018 12:39PM	Mar 21 2018 8:26AM	S	Gallo
19	703651	21010	ACIS-S	NONE	3.600000	3.492606	UGC08839	archived	Feb 26 2018 12:39PM	Apr 3 2018 5:04PM	S	Gallo
19	703650	21009	ACIS-S	NONE	3.600000	3.651473	LSBCF574-07	archived	Feb 26 2018 12:39PM	May 10 2018 2:20PM	S	Gallo
19	703649	21008	ACIS-S	NONE	3.200000	3.297175	LSBCF574-08	archived	Feb 26 2018 12:39PM	Jun 25 2018 9:22PM	S	Gallo
19	703648	21007	ACIS-S	NONE	3.200000	3.253765	CGCG098-132	archived	Feb 26 2018 12:39PM	Jun 8 2018 11:49AM	S	Gallo
19	703647	21006	ACIS-S	NONE	3.200000	3.329400	LSBCF570-04	archived	Feb 26 2018 12:39PM	Jun 10 2018 12:24AM	S	Gallo
19	503051	21005	ACIS-S	NONE	22.000000	21.963000	SN2013df	archived	Feb 26 2018 12:38PM	Mar 26 2018 8:10PM	S	Patnaude
19	503050	21004	ACIS-S	NONE	15.000000	15.090000	SN2003gk	archived	Feb 26 2018 12:38PM	Aug 21 2018 2:14AM	S	Patnaude
19	503049	21003	ACIS-S	NONE	22.000000	22.092000	SN2013ak	archived	Feb 26 2018 12:38PM	Aug 5 2018 8:04PM	S	Patnaude
19	503048	21002	ACIS-S	NONE	10.000000	10.092000	SN2013by	archived	Feb 26 2018 12:38PM	Jun 19 2018 5:42AM	S	Patnaude
19	503047	21001	ACIS-S	NONE	10.000000	10.091451	SN2012aw	archived	Feb 26 2018 12:38PM	Mar 26 2018 4:54PM	S	Patnaude
19	503046	21000	ACIS-S	NONE	10.000000	10.091748	SN2013ej	archived	Feb 26 2018 12:38PM	Sep 30 2018 8:35PM	S	Patnaude
19	503045	20999	ACIS-S	NONE	15.000000	15.089764	SN2008ax	archived	Feb 26 2018 12:38PM	Nov 6 2018 2:46AM	S	Patnaude
19	503044	20998	ACIS-S	NONE	20.000000	20.091000	SN2011dh	archived	Feb 26 2018 12:38PM	Aug 31 2018 4:28PM	S	Patnaude
19	503043	20997	ACIS-S	NONE	19.000000	20.990564	SN2011ja	archived	Feb 26 2018 12:38PM	Apr 24 2018 9:33PM	S	Patnaude
19	201206	20996	HRC-I	NONE	50.000000	50.055878	ALPHABOO	archived	Feb 26 2018 12:37PM	Jun 9 2018 10:06AM	S	AYRES
19	402024	20995	ACIS-S	NONE	17.000000	16.244000	NGC5907	archived	Feb 22 2018 9:22AM	Mar 1 2018 4:42AM	D	Pintore
19	402024	20994	ACIS-S	NONE	33.000000	33.049100	NGC5907	archived	Feb 21 2018 10:51PM	Feb 27 2018 1:40PM	D	Pintore
19	201205	20987	HRC-I	NONE	5.000000	5.180350	ALPHACENTAURI	archived	Feb 16 2018 9:52AM	May 18 2018 5:25PM	N	AYRES
19	402022	20966	ACIS-S	NONE	10.000000	10.069904	NGC300ULX-1	archived	Jan 26 2018 10:21PM	Feb 11 2018 4:49PM	D	Vasilopoulos
19	402021	20965	ACIS-S	NONE	10.000000	10.070236	NGC300ULX-1	archived	Jan 26 2018 10:21PM	Feb 8 2018 3:10AM	D	Vasilopoulos
19	402020	20945	ACIS-S	NONE	13.000000	14.405700	GW170817	archived	Jan 18 2018 4:25PM	Jan 28 2018 4:29AM	N	Wilkes
19	402020	20939	ACIS-S	NONE	19.700000	22.541809	GW170817	archived	Jan 7 2018 10:35PM	Jan 24 2018 8:18AM	N	Wilkes
19	402020	20938	ACIS-S	NONE	16.000000	16.067231	GW170817	archived	Jan 7 2018 10:35PM	Jan 21 2018 1:45PM	N	Wilkes
19	402020	20937	ACIS-S	NONE	19.100000	21.045162	GW170817	archived	Jan 7 2018 10:34PM	Jan 23 2018 8:02AM	N	Wilkes
19	402020	20936	ACIS-S	NONE	32.200000	32.168700	GW170817	archived	Jan 5 2018 2:26PM	Jan 17 2018 9:55PM	N	Wilkes
18	402019	20928	ACIS-S	NONE	10.000000	10.068146	LSV+2225	archived	Dec 22 2017 1:17PM	Jan 13 2018 3:23PM	D	Liu
18	703470	20887	ACIS-S	NONE	22.500000	20.654316	QSOJ1342+0928	archived	Dec 1 2017 12:31PM	Dec 17 2017 7:01AM	D	Banados
18	201204	20875	ACIS-S	NONE	4.000000	4.091577	DMTau	archived	Nov 22 2017 11:54AM	Jan 25 2018 8:15AM	N	Cleeves
18	201203	20874	ACIS-S	NONE	4.000000	4.092000	DMTau	archived	Nov 22 2017 11:54AM	Jan 17 2018 7:57PM	N	Cleeves
18	201202	20873	ACIS-S	NONE	4.000000	4.092000	DMTau	archived	Nov 22 2017 11:54AM	Jan 9 2018 10:33PM	N	Cleeves
18	201201	20872	ACIS-S	NONE	4.000000	4.092000	DMTau	archived	Nov 22 2017 11:54AM	Jan 4 2018 11:59AM	N	Cleeves
18	201200	20871	ACIS-S	NONE	4.000000	4.090868	DMTau	archived	Nov 22 2017 11:54AM	Dec 27 2017 3:11PM	N	Cleeves
18	201199	20870	ACIS-S	NONE	4.000000	4.092000	DMTau	archived	Nov 22 2017 11:54AM	Dec 21 2017 6:48AM	N	Cleeves
18	201198	20869	ACIS-S	NONE	4.000000	4.092000	DMTau	archived	Nov 22 2017 11:54AM	Dec 14 2017 12:03AM	N	Cleeves
18	402012	20861	ACIS-S	NONE	25.000000	25.068738	GW170817	archived	Nov 16 2017 11:52AM	Dec 6 2017 11:02AM	N	Wilkes
18	402012	20860	ACIS-S	NONE	75.000000	75.066017	GW170817	archived	Nov 16 2017 11:48AM	Dec 3 2017 1:59AM	N	Wilkes
18	402011	20859	ACIS-S	HETG	25.000000	25.090000	SwiftJ0243.6+6124	archived	Nov 8 2017 1:06PM	Nov 11 2017 11:20AM	D	Degenaar
18	801803	20851	ACIS-I	NONE	34.000000	31.734444	1RXSJ032401.8+24213	archived	Nov 6 2017 4:45PM	Jan 2 2018 1:17AM	N	Ebeling
18	100171	20847	HRC-I	NONE	25.000000	25.050233	Uranus	archived	Oct 29 2017 1:57PM	Nov 12 2017 1:14PM	D	Dunn
18	100171	20846	HRC-I	NONE	25.000000	25.144533	Uranus	archived	Oct 29 2017 12:00PM	Nov 11 2017 7:47PM	D	Dunn
18	201197	20831	ACIS-S	NONE	10.000000	10.065700	AT2017gbl	archived	Oct 17 2017 3:45PM	Nov 3 2017 12:18PM	N	Heikkila
18	402010	20830	ACIS-S	NONE	50.000000	51.946700	NGC5907ULX	archived	Oct 17 2017 12:11PM	Nov 7 2017 6:11AM	D	belfiore
18	503034	20728	ACIS-S	NONE	50.000000	47.309100	GRB170817A	archived	Aug 29 2017 12:49PM	Sep 1 2017 3:43PM	D	Troja
18	300403	20632	HRC-S	LETG	35.000000	34.406433	NovaLup2016	archived	Aug 11 2017 3:25PM	Aug 30 2017 3:37PM	N	Orio
18	703616	20625	ACIS-S	NONE	10.000000	10.061465	AT2017eqx	archived	Jul 31 2017 3:41PM	Aug 16 2017 10:53AM	D	Nicholl
18	503033	20613	ACIS-S	NONE	15.000000	15.059262	GRB170714A	archived	Jul 24 2017 4:32PM	Jul 28 2017 11:57AM	N	Troja
18	703470	20124	ACIS-S	NONE	27.500000	25.059603	QSOJ1342+0928	archived	Jul 12 2017 4:47PM	Dec 15 2017 1:55PM	D	Banados
18	703469	20115	ACIS-S	NONE	10.000000	10.089000	SDSSJ135750.71+22310	archived	Jun 29 2017 7:05PM	Aug 27 2017 7:51AM	N	Chilingarian
18	703468	20114	ACIS-S	NONE	10.000000	10.092000	SDSSJ110731.23+13471	archived	Jun 29 2017 7:05PM	Jul 17 2017 12:21AM	N	Chilingarian
18	401894	20098	HRC-S	NONE	30.000000	30.092977	MAXIJ0911-655	archived	Jun 1 2017 12:26PM	Jun 25 2017 7:07AM	D	Riggio
18	401893	20083	ACIS-S	NONE	8.000000	7.678800	SWIFTJ175233.9-2909	archived	May 15 2017 4:03PM	May 25 2017 3:36AM	N	Maccarone
18	502973	20055	ACIS-S	NONE	50.000000	51.010332	SN2017cbv	archived	Mar 23 2017 2:47PM	Mar 27 2017 11:54AM	D	Drout
18	401892	20054	ACIS-I	NONE	65.000000	65.099750	PSRB1259-63	archived	Mar 17 2017 11:23AM	Apr 24 2017 5:27AM	N	Pavlov
18	703466	20035	ACIS-S	NONE	14.400000	14.469199	M87	archived	Feb 27 2017 7:29PM	Apr 14 2017 2:13AM	N	Neilsen
18	703466	20034	ACIS-S	NONE	14.400000	14.467599	M87	archived	Feb 27 2017 3:14PM	Apr 12 2017 12:00AM	N	Neilsen
18	703465	20021	ACIS-S	NONE	10.000000	10.049712	WPVS007	archived	Feb 16 2017 5:44PM	Mar 16 2017 3:24PM	N	Grupe
18	401891	20008	ACIS-S	HETG	30.000000	30.071250	GRS1716-249	archived	Jan 31 2017 1:22PM	Feb 6 2017 12:24PM	D	Miller
18	100168	20002	HRC-I	NONE	36.000000	36.164821	Jupiter	archived	Jan 26 2017 2:50PM	Aug 6 2017 2:08AM	N	Jackman
18	100167	20001	HRC-I	NONE	36.000000	37.147283	Jupiter	archived	Jan 26 2017 2:50PM	Jun 18 2017 6:57PM	N	Jackman
18	100166	20000	HRC-I	NONE	72.000000	72.138735	Jupiter	archived	Jan 26 2017 2:50PM	Feb 28 2017 12:53PM	N	Jackman
18	502972	19999	ACIS-S	NONE	10.000000	9.978900	iPTF17cw	archived	Jan 23 2017 5:25PM	Feb 8 2017 9:39AM	D	Corsi
17	703464	19990	ACIS-S	NONE	30.000000	30.090000	SDSSJ140737.16+4428	archived	Jan 11 2017 10:36AM	Feb 25 2017 2:51PM	D	Secrest
17	502971	19986	ACIS-S	NONE	30.000000	29.771358	CRTSCSS161010J0458	archived	Dec 21 2016 4:13PM	Jul 23 2017 9:17PM	D	MARGUTTI
17	502970	19985	ACIS-S	NONE	30.000000	27.416074	CRTSCSS161010J0458	archived	Dec 21 2016 4:13PM	Feb 13 2017 12:16PM	D	MARGUTTI
17	502969	19984	ACIS-S	NONE	30.000000	30.045200	CRTSCSS161010J0458	archived	Dec 21 2016 4:13PM	Jan 13 2017 11:32PM	D	MARGUTTI
17	300401	19983	HRC-S	LETG	50.000000	50.185284	ASASSN-16oh	archived	Dec 19 2016 2:25PM	Dec 28 2016 9:27PM	D	Maccarone
17	401890	19904	ACIS-S	HETG	30.000000	31.052750	4U1630-47	archived	Oct 6 2016 2:17PM	Oct 21 2016 1:43AM	D	Bhattacharyya
17	401889	19891	ACIS-S	NONE	35.000000	36.302609	CXOUJ103844.8+53300	archived	Sep 22 2016 2:40PM	Oct 22 2016 4:32PM	N	Earnshaw
17	201154	19793	HRC-I	NONE	11.250000	10.889601	ProximaCen	archived	Sep 6 2016 5:03PM	Dec 8 2016 8:29PM	N	Wargelin
17	201153	19790	HRC-I	NONE	11.250000	10.889729	ProximaCen	archived	Sep 1 2016 4:40PM	Nov 3 2016 6:43PM	N	Wargelin
17	201152	19789	HRC-I	NONE	11.250000	10.922401	ProximaCen	archived	Sep 1 2016 4:40PM	Oct 14 2016 6:31PM	N	Wargelin
17	201151	19788	HRC-I	NONE	11.250000	12.464001	ProximaCen	archived	Sep 1 2016 4:40PM	Sep 26 2016 8:12AM	N	Wargelin
17	401888	19787	ACIS-S	HETG	15.000000	15.040450	SMCX-3	archived	Aug 30 2016 11:23AM	Sep 7 2016 4:45PM	D	Coe
17	401888	19786	ACIS-S	HETG	25.000000	24.042227	SMCX-3	archived	Aug 30 2016 11:18AM	Sep 6 2016 7:50PM	D	Coe
17	401881	19691	ACIS-I	NONE	1.000000	1.081900	PMNJ0032-7306	archived	Aug 3 2016 2:10PM	Aug 11 2016 11:00PM	D	Kennea
17	502963	19690	ACIS-S	NONE	60.000000	56.230900	PSRJ1119-6127	archived	Aug 2 2016 6:22PM	Oct 27 2016 6:38PM	N	Blumer
17	300392	18889	ACIS-S	NONE	18.000000	18.027750	FOAqr	archived	Jul 14 2016 11:46AM	Jul 26 2016 7:26AM	N	Kennedy
17	401819	18885	ACIS-S	NONE	25.000000	25.535198	XMMUJ004855.5-73494	archived	Jun 30 2016 11:04AM	Jul 6 2016 8:43AM	N	Vasilopoulos
17	502667	18884	ACIS-S	NONE	20.000000	20.069599	SGR1935+2154	archived	Jun 29 2016 3:51PM	Jul 7 2016 5:43AM	D	Kouveliotou
17	502666	18880	ACIS-S	NONE	30.000000	29.047000	Gaia16apd	archived	Jun 27 2016 12:27PM	Mar 19 2017 5:29PM	D	Yan
17	502665	18879	ACIS-S	NONE	30.000000	30.032422	Gaia16apd	archived	Jun 27 2016 12:27PM	Oct 23 2016 6:11PM	D	Yan
17	502664	18878	ACIS-S	NONE	47.000000	44.185500	PKS1613-50	archived	Jun 23 2016 2:38PM	Jun 25 2016 9:30AM	D	Rea
17	502663	18827	ACIS-S	NONE	15.000000	15.081000	SN2016bkv	archived	Apr 1 2016 1:03PM	Apr 20 2016 4:10AM	N	Patnaude
17	401818	18815	ACIS-S	NONE	30.000000	30.090000	HETEJ1900.1-2455	archived	Mar 17 2016 5:15PM	Apr 18 2016 10:09PM	D	Degenaar
17	703301	18813	ACIS-S	NONE	5.000000	5.068768	M87	archived	Mar 9 2016 8:02PM	Mar 17 2016 3:43AM	N	Cheung
17	703300	18812	ACIS-S	NONE	5.000000	4.853443	M87	archived	Mar 9 2016 8:02PM	Mar 16 2016 12:27AM	N	Cheung
17	703299	18811	ACIS-S	NONE	5.000000	5.069200	M87	archived	Mar 9 2016 8:02PM	Mar 14 2016 1:44PM	N	Cheung
17	703298	18810	ACIS-S	NONE	5.000000	5.069600	M87	archived	Mar 9 2016 8:02PM	Mar 13 2016 7:25AM	N	Cheung
17	703297	18809	ACIS-S	NONE	5.000000	4.984400	M87	archived	Mar 9 2016 8:02PM	Mar 12 2016 5:07AM	N	Cheung
17	703296	18804	ACIS-S	NONE	30.000000	30.062316	QSO2237+0305	archived	Mar 9 2016 1:39PM	Apr 24 2016 5:27AM	N	Pooley
17	502662	18802	ACIS-S	NONE	36.000000	36.062177	SN2005ip	archived	Mar 2 2016 12:16PM	Apr 4 2016 2:16AM	N	Mauerhan
17	300391	18800	ACIS-S	NONE	25.000000	25.103556	MWC560	archived	Feb 25 2016 5:26PM	Mar 9 2016 2:20AM	D	Lucy
17	300391	18790	ACIS-S	NONE	25.000000	25.101000	MWC560	archived	Feb 23 2016 2:41PM	Mar 8 2016 7:17AM	D	Lucy
17	703295	18789	ACIS-S	NONE	30.000000	29.978798	Mrk1018	archived	Feb 18 2016 12:45PM	Feb 25 2016 2:37AM	D	Tremblay
17	401817	18788	ACIS-S	NONE	5.000000	4.956140	PSRJ2032+4127	archived	Feb 15 2016 5:13PM	Feb 24 2016 8:23AM	N	Ho
17	502661	18760	ACIS-S	NONE	5.000000	5.025100	ASASSN16at	archived	Jan 26 2016 11:14AM	Feb 6 2016 6:57AM	N	Grupe
16	201084	18725	ACIS-S	NONE	20.000000	20.094000	HD97658	archived	Dec 3 2015 10:31AM	Mar 5 2016 4:21PM	D	Wheatley
16	201084	18724	ACIS-S	NONE	20.000000	20.094000	HD97658	archived	Dec 3 2015 9:52AM	Dec 11 2015 1:01PM	D	Wheatley
16	502660	18717	ACIS-S	NONE	40.000000	40.092000	FRB121102	archived	Nov 19 2015 11:14AM	Nov 23 2015 10:37AM	D	Scholz
16	401816	18686	HRC-S	NONE	2.800000	2.938931	SMCX-2	archived	Oct 1 2015 5:25PM	Nov 5 2015 6:56PM	N	Li
16	703280	18352	ACIS-S	NONE	10.000000	10.124600	NGC660	archived	Jul 22 2015 3:32PM	Aug 26 2015 8:37PM	N	Annuar
16	100155	17709	ACIS-S	NONE	110.000000	107.221501	Pluto(134340)	archived	Jul 15 2015 3:19PM	Aug 1 2015 9:30PM	N	McNutt
16	100155	17708	ACIS-S	NONE	16.000000	17.595600	Pluto(134340)	archived	Jul 15 2015 3:19PM	Jul 30 2015 5:30AM	N	McNutt
16	401698	17704	ACIS-S	NONE	28.000000	28.752000	V404Cyg	archived	Jul 14 2015 3:56PM	Jul 25 2015 6:46PM	N	Heinz
16	100155	17703	ACIS-S	NONE	14.000000	14.088741	Pluto(134340)	archived	Jul 9 2015 1:59PM	Jul 27 2015 12:09AM	N	McNutt
16	401697	17701	ACIS-S	HETG	40.000000	40.035879	V404Cyg	archived	Jul 2 2015 3:23PM	Jul 11 2015 1:17PM	N	Neilsen
16	401696	17697	ACIS-S	HETG	25.000000	24.712915	v404Cyg	archived	Jun 22 2015 7:37PM	Jun 23 2015 9:40PM	N	King
16	401695	17696	ACIS-S	HETG	30.000000	29.307864	v404Cyg	archived	Jun 19 2015 9:29AM	Jun 22 2015 1:56PM	N	King
16	401694	17678	ACIS-I	NONE	10.000000	10.102500	M82	archived	Jun 5 2015 2:09PM	Jun 21 2015 3:12AM	N	Brightman
16	502493	17673	ACIS-S	NONE	10.000000	10.061636	SNhunt275	archived	May 26 2015 3:17PM	Sep 20 2015 11:42PM	N	MARGUTTI
16	502492	17672	ACIS-S	NONE	10.000000	10.046760	SNhunt275	archived	May 26 2015 3:17PM	Jun 8 2015 2:04AM	N	MARGUTTI
16	401693	17662	ACIS-I	NONE	5.000000	5.080900	2S1553-542	archived	May 13 2015 4:36PM	May 21 2015 4:53PM	D	Lutovinov
16	401692	17661	HRC-S	NONE	30.000000	29.765233	SAXJ1808.4-3658	archived	May 11 2015 2:47PM	May 24 2015 10:29PM	D	Patruno
16	502491	17658	ACIS-S	NONE	25.000000	23.643700	GRB150423A	archived	Apr 28 2015 3:13PM	May 2 2015 7:39AM	N	Berger
16	401691	17649	ACIS-S	HETG	30.000000	30.073000	1RXSJ180408.9-34205	archived	Apr 7 2015 1:46PM	Apr 14 2015 3:08PM	D	Degenaar
16	300338	17648	ACIS-S	HETG	35.000000	34.947201	GKPersei	archived	Mar 29 2015 7:31AM	Apr 4 2015 8:21AM	N	Orio
16	201026	17644	ACIS-S	NONE	40.000000	38.690798	RWAur	archived	Mar 20 2015 3:47PM	Apr 16 2015 6:56AM	N	Schneider
16	502490	17639	ACIS-S	NONE	50.000000	47.108715	CasACCO	archived	Mar 9 2015 4:35PM	May 1 2015 2:18AM	N	Posselt
16	401690	17637	ACIS-S	NONE	10.000000	10.075000	[PFH2005]622	archived	Mar 4 2015 2:19PM	Mar 6 2015 4:48PM	N	Burrows
16	703155	17636	ACIS-S	NONE	10.000000	10.056400	WPVS007	archived	Mar 4 2015 9:08AM	Mar 28 2015 8:20AM	N	Grupe
16	401689	17631	HRC-I	NONE	10.000000	10.153651	FRB150215	archived	Feb 15 2015 11:51PM	Feb 18 2015 4:11AM	D	Petroff
16	401688	17630	ACIS-S	HETG	15.000000	14.457600	4U1700-37	archived	Feb 12 2015 5:51PM	Feb 22 2015 3:30AM	N	Oskinova
16	703154	17594	ACIS-S	NONE	15.000000	15.058837	SWIFTJ123205.1-1056	archived	Jan 14 2015 5:56PM	Feb 10 2015 5:35AM	N	Levan
16	502489	17586	ACIS-S	NONE	15.000000	15.066000	SwiftJ123205.1-1056	archived	Jan 6 2015 2:57PM	Jan 9 2015 11:55AM	N	Troja
15	502488	17571	ACIS-S	NONE	10.000000	10.056279	SN2014C	archived	Dec 15 2014 12:02PM	Aug 28 2015 9:03AM	N	MARGUTTI
15	502487	17570	ACIS-S	NONE	10.000000	10.024851	SN2014C	archived	Dec 15 2014 12:02PM	Apr 20 2015 10:47PM	N	MARGUTTI
15	502486	17569	ACIS-S	NONE	10.000000	10.045655	SN2014C	archived	Dec 15 2014 12:02PM	Jan 30 2015 3:22PM	N	MARGUTTI
15	703152	17567	HRC-S	LETG	45.000000	44.793784	ASASSN-14li	archived	Dec 4 2014 5:21PM	Dec 11 2014 9:09AM	N	Miller
15	703152	17566	HRC-S	LETG	35.000000	35.039883	ASASSN-14li	archived	Dec 4 2014 4:24PM	Dec 8 2014 11:29PM	N	Miller
15	401686	17559	ACIS-S	NONE	40.000000	40.114000	CXOJ122518.6+144545	archived	Nov 26 2014 11:33AM	Dec 15 2014 6:27AM	D	Heida
15	401685	17558	ACIS-S	NONE	20.000000	19.985700	CXOJ122518.6+144545	archived	Nov 26 2014 11:33AM	Dec 8 2014 5:42PM	D	Heida
15	502485	17550	ACIS-S	NONE	20.000000	20.058751	PSNJ12215757+042818	archived	Nov 4 2014 4:44PM	Nov 16 2014 3:28PM	N	MARGUTTI
15	703151	17547	ACIS-S	NONE	5.000000	5.071600	NGC247	archived	Oct 22 2014 11:11AM	Nov 12 2014 5:54AM	D	Feng
15	703150	17538	ACIS-S	NONE	20.000000	20.078069	SDSSJ152304.97+1145	archived	Sep 26 2014 9:55AM	Dec 26 2014 4:59AM	D	Gallo
15	502479	17314	ACIS-S	NONE	30.000000	29.154750	SGR1935+2154	archived	Aug 7 2014 3:43PM	Aug 31 2014 12:59AM	D	Rea
15	200968	16631	ACIS-S	NONE	25.000000	23.011038	V1180Cas	archived	Jun 20 2014 3:48PM	Aug 2 2014 10:11PM	N	Nucita
15	401615	16625	ACIS-S	NONE	5.000000	5.147250	PSRB1259-63	archived	Jun 16 2014 12:48PM	Jun 25 2014 7:03PM	N	Bordas
15	401614	16624	ACIS-S	NONE	5.000000	5.174750	PSRB1259-63	archived	Jun 16 2014 12:48PM	Jun 23 2014 6:46PM	N	Bordas
15	502271	16618	ACIS-S	NONE	20.000000	20.063200	GRB140515A	archived	May 20 2014 1:07PM	May 25 2014 7:54AM	N	MARGUTTI
15	401613	16606	ACIS-S	HETG	35.000000	35.082250	GROJ1744-28	archived	Mar 22 2014 7:58PM	Mar 31 2014 12:48AM	D	Miller
15	401613	16605	ACIS-S	HETG	35.000000	35.073250	GROJ1744-28	archived	Mar 22 2014 6:28PM	Mar 29 2014 7:09PM	D	Miller
15	401612	16596	ACIS-S	HETG	10.000000	10.077500	GROJ1744-28	archived	Feb 17 2014 5:12PM	Mar 3 2014 9:15AM	D	Kennea
14	401611	16583	ACIS-I	NONE	30.000000	28.538149	PSRB1259-63	archived	Jan 23 2014 6:17PM	Feb 9 2014 7:49AM	N	Pavlov
15	502269	16580	ACIS-S	NONE	50.000000	47.465954	SN2014J	archived	Jan 23 2014 12:03PM	Feb 3 2014 8:26PM	N	MARGUTTI
15	200967	16577	ACIS-S	NONE	10.000000	9.964800	KOI-314	archived	Jan 21 2014 1:27PM	Feb 7 2014 9:42PM	D	Poppenhaeger
14	401611	16563	ACIS-I	NONE	35.000000	32.061376	PSRB1259-63	archived	Dec 19 2013 4:13PM	Feb 8 2014 1:42PM	N	Pavlov
14	401610	16561	ACIS-S	NONE	30.000000	30.578400	XSSJ12270-4859	archived	Dec 16 2013 1:33PM	Jan 11 2014 5:14AM	D	Patruno
14	502268	16556	ACIS-S	NONE	20.000000	19.064984	SN2013ge	archived	Dec 2 2013 12:21PM	Dec 7 2013 6:08PM	N	MARGUTTI
14	502266	16488	ACIS-S	NONE	50.000000	46.073786	GRB130925A	archived	Oct 1 2013 2:36PM	Oct 6 2013 4:22AM	D	Bellm
14	502265	16441	ACIS-S	NONE	15.000000	15.069100	GRB130831A	archived	Sep 9 2013 3:31PM	Oct 3 2013 1:27PM	D	DePasquale
14	502264	16440	ACIS-S	NONE	15.000000	14.641300	GRB130831A	archived	Sep 9 2013 3:31PM	Sep 17 2013 1:21AM	D	DePasquale
14	502037	15663	ACIS-S	NONE	30.000000	29.964800	GRB130606A	archived	Jun 12 2013 10:10AM	Jun 17 2013 3:29AM	D	Berger
14	601099	15648	ACIS-S	NONE	25.000000	25.062680	[SRW2012]Src.3c	archived	May 9 2013 3:19PM	May 24 2013 12:22PM	N	Roberts
14	702923	15647	ACIS-S	HETG	30.000000	30.554400	Mrk590	archived	May 2 2013 9:55AM	Jun 16 2013 7:33AM	N	Mathur
14	401541	15646	ACIS-S	NONE	15.000000	13.753555	NGC404	archived	Apr 26 2013 5:16PM	Jun 4 2013 2:44AM	N	Kaaret
14	401540	15645	HRC-S	NONE	53.000000	53.041959	IGRJ18245-2452	archived	Apr 26 2013 10:08AM	Apr 29 2013 12:24AM	D	Patto
14	100095	15641	ACIS-S	NONE	5.000000	5.183200	Comet2011L4(PANST	archived	Mar 20 2013 4:41PM	Apr 24 2013 12:47AM	N	Lisse
14	100094	15640	ACIS-S	NONE	5.000000	5.180100	Comet2011L4(PANST	archived	Mar 20 2013 4:39PM	Apr 21 2013 2:39PM	N	Lisse
14	100093	15639	ACIS-S	NONE	5.000000	5.177000	Comet2011L4(PANST	archived	Mar 20 2013 4:38PM	Apr 17 2013 9:44AM	N	Lisse
14	702922	15637	ACIS-S	NONE	15.000000	15.069100	2XMMIJ184725.1-6317	archived	Mar 18 2013 5:51PM	Mar 29 2013 4:28AM	D	Lin
14	100097	15631	HRC-I	NONE	5.000000	5.181632	Comet2011L4(PANST	archived	Mar 14 2013 10:19PM	Apr 24 2013 2:21AM	N	Lisse
14	100096	15630	HRC-I	NONE	5.000000	5.189832	Comet2011L4(PANST	archived	Mar 14 2013 10:19PM	Apr 17 2013 11:17AM	N	Lisse
14	100095	15629	ACIS-S	NONE	5.000000	5.071600	Comet2011L4(PANST	archived	Mar 14 2013 10:19PM	Apr 23 2013 11:15PM	N	Lisse
14	100094	15628	ACIS-S	NONE	5.000000	5.074700	Comet2011L4(PANST	archived	Mar 14 2013 10:19PM	Apr 21 2013 1:07PM	N	Lisse
14	100093	15627	ACIS-S	NONE	5.000000	5.070699	Comet2011L4(PANST	archived	Mar 14 2013 10:19PM	Apr 17 2013 8:12AM	N	Lisse
14	901095	15625	ACIS-S	NONE	10.000000	9.964770	NuSTARJ163433-4738.	archived	Mar 11 2013 3:12PM	Mar 23 2013 8:46AM	D	Tomsick
14	300318	15620	HRC-I	NONE	5.000000	5.179582	M31N2013-01b	archived	Mar 1 2013 12:52PM	Mar 11 2013 11:16PM	N	Henze
14	502032	15616	ACIS-S	NONE	2.000000	2.064600	M82	archived	Feb 11 2013 5:01PM	Feb 24 2013 11:25PM	N	Madej
13	200910	15597	ACIS-S	NONE	25.000000	25.074440	CRTSMLS121106J0144	archived	Nov 19 2012 8:10PM	Nov 23 2012 5:02PM	D	Vianello
13	300317	15596	HRC-S	LETG	25.000000	25.119933	NovaMon2012	archived	Nov 19 2012 2:11PM	Dec 3 2012 8:01PM	N	Orio
13	702920	15584	ACIS-S	NONE	25.000000	24.966258	SwiftJ1644+57	archived	Nov 1 2012 10:24AM	Nov 26 2012 10:25AM	N	Tanvir
13	300316	15495	ACIS-S	HETG	25.000000	25.049135	PNVJ06393874+055352	archived	Aug 29 2012 4:40PM	Sep 12 2012 9:13AM	N	Ness
13	502021	15268	ACIS-S	NONE	20.000000	20.068815	GRB120804A	archived	Aug 7 2012 2:47PM	Aug 13 2012 11:11AM	N	Troja
13	502020	15265	HRC-I	NONE	10.000000	10.124182	1E2259+586	archived	Jul 31 2012 12:04PM	Aug 21 2012 4:51PM	D	Kas
13	501800	14464	ACIS-S	NONE	10.000000	10.068800	GRB120624B	archived	Jun 28 2012 11:30AM	Jun 30 2012 9:24AM	N	Campana
13	401435	14442	ACIS-S	NONE	20.000000	20.065073	NGC4088	archived	May 25 2012 4:51PM	Jun 2 2012 3:30AM	D	Mezcua
13	401434	14441	ACIS-S	HETG	20.000000	19.073250	4U1630-47	archived	May 24 2012 2:28PM	Jun 3 2012 10:28PM	D	Neilsen
13	401430	14428	ACIS-S	HETG	20.000000	20.103500	SwiftJ1753.5-0127	archived	Apr 26 2012 12:18PM	May 3 2012 3:25PM	D	Soleri
13	300312	14426	HRC-S	LETG	20.000000	20.189682	NovaLMC2012	archived	Apr 17 2012 6:34PM	Apr 26 2012 10:12PM	N	Drake
13	401429	14425	ACIS-S	HETG	30.000000	30.088300	MAXIJ1305-704	archived	Apr 16 2012 2:32PM	Apr 29 2012 7:20PM	D	Miller
13	501797	14420	ACIS-S	NONE	20.000000	20.398000	PTF11qcj	archived	Mar 28 2012 2:18PM	Apr 11 2012 8:55AM	N	Corsi
13	501796	14412	ACIS-S	NONE	40.000000	39.641600	SN2011ja	archived	Mar 13 2012 2:26PM	Apr 3 2012 5:10AM	D	Ray
13	200830	14402	ACIS-S	NONE	20.000000	20.069599	55Cnc	archived	Feb 23 2012 2:57PM	Apr 5 2012 1:03PM	D	Wheatley
13	200829	14401	ACIS-S	NONE	12.000000	11.786399	55Cnc	archived	Feb 23 2012 2:56PM	Mar 7 2012 2:11AM	D	Wheatley
13	501794	14398	ACIS-S	NONE	10.000000	10.062600	PTF11qcj	archived	Feb 9 2012 12:09PM	Feb 26 2012 9:15AM	N	Corsi
13	501793	14382	ACIS-S	NONE	10.000000	9.961085	PTF11qcj	archived	Dec 27 2011 1:24PM	Jan 13 2012 1:43AM	N	Corsi
13	401427	14376	ACIS-S	NONE	2.000000	2.010400	NGC891ULX1	archived	Dec 5 2011 4:45PM	Dec 20 2011 7:12AM	N	Hodges-Kluck
13	501792	14360	ACIS-S	NONE	20.000000	21.010349	CXOUJ164710.2-45521	archived	Oct 12 2011 11:14AM	Oct 23 2011 3:56PM	D	Israel
12	501791	14341	ACIS-S	NONE	40.000000	49.715200	PTF11kly	archived	Aug 26 2011 10:09AM	Aug 27 2011 11:00AM	N	Hughes
12	401425	14337	ACIS-S	HETG	14.000000	14.047270	IGRJ17498-2921	archived	Aug 24 2011 8:50AM	Aug 29 2011 2:22PM	N	DiSalvo
12	401425	14336	ACIS-S	HETG	16.000000	16.345000	IGRJ17498-2921	archived	Aug 19 2011 3:02PM	Aug 30 2011 1:36PM	N	DiSalvo
12	501789	14329	ACIS-S	NONE	15.000000	14.350399	SwiftJ1834.9-0846	archived	Aug 11 2011 2:56AM	Aug 22 2011 3:46PM	N	Kargaltsev
12	501788	14237	ACIS-S	NONE	10.000000	10.043925	GRB110709B	archived	Aug 3 2011 2:39PM	Oct 31 2011 8:15PM	N	Levan
12	501567	13511	HRC-I	NONE	1.000000	1.181953	SwiftJ1822.3-1606	archived	Jul 18 2011 2:48PM	Jul 28 2011 8:21PM	D	Kouveliotou
12	702582	13423	HRC-I	NONE	5.000000	5.187525	SWIFTJ2058.4+0516	archived	Jun 13 2011 12:57PM	Jun 22 2011 3:04PM	N	Cenko
12	401300	13420	HRC-I	NONE	1.000000	1.530581	M15	archived	May 18 2011 4:15PM	May 30 2011 4:54PM	N	Sivakoff
12	501563	13419	ACIS-S	NONE	5.000000	5.043424	SNRG306.3-0.9	archived	May 6 2011 2:58PM	Jun 2 2011 2:06PM	N	Miller
12	702581	13418	ACIS-S	NONE	10.000000	10.040058	PS1-10jh	archived	Apr 29 2011 10:54AM	May 22 2011 11:16PM	N	Gezari
12	401297	13252	ACIS-S	NONE	40.000000	40.080000	PSRJ1748-2446am	archived	Mar 31 2011 10:28AM	Apr 29 2011 5:30PM	D	Degenaar
12	200735	13250	ACIS-S	LETG	20.000000	20.075300	TWHya	archived	Mar 29 2011 4:23PM	Apr 13 2011 12:00PM	N	Guenther
12	401295	13237	ACIS-S	NONE	40.000000	40.077250	HESSJ0632+057	archived	Feb 9 2011 2:40PM	Feb 13 2011 9:28PM	D	Torres
12	401293	13225	ACIS-S	NONE	30.000000	30.078000	PSRJ1748-2446am	archived	Jan 24 2011 2:02PM	Feb 17 2011 9:31AM	D	Wijnands
12	401292	13219	ACIS-S	HETG	12.000000	12.000000	CygX-1	archived	Jan 19 2011 9:47AM	Feb 5 2011 6:56AM	N	McClintock
12	501549	13217	ACIS-S	NONE	15.000000	15.010343	XTEJ1810-197	archived	Jan 12 2011 12:23AM	Feb 9 2011 12:04AM	D	Perna
12	600982	13212	ACIS-S	NONE	10.000000	10.186400	NGC1589-OT	archived	Dec 23 2010 3:54PM	Jan 16 2011 3:58AM	N	Filippenko
12	501548	13210	ACIS-S	NONE	5.000000	5.000000	Crab	archived	Dec 14 2010 12:26PM	Oct 15 2011 4:51AM	N	Weisskopf
12	501547	13209	ACIS-S	NONE	5.000000	5.000000	Crab	archived	Dec 14 2010 12:26PM	Sep 15 2011 4:09AM	N	Weisskopf
12	501546	13208	ACIS-S	NONE	5.000000	5.000000	Crab	archived	Dec 14 2010 12:26PM	Aug 15 2011 9:01AM	N	Weisskopf
12	501545	13207	ACIS-S	NONE	5.000000	5.000000	Crab	archived	Dec 14 2010 12:26PM	Apr 12 2011 2:15PM	N	Weisskopf
12	501544	13206	ACIS-S	NONE	5.000000	5.000000	Crab	archived	Dec 14 2010 12:26PM	Mar 15 2011 6:04AM	N	Weisskopf
12	501543	13205	ACIS-S	NONE	5.000000	5.000000	Crab	archived	Dec 14 2010 12:26PM	Feb 16 2011 4:52PM	N	Weisskopf
12	501542	13204	ACIS-S	NONE	5.000000	3.323628	Crab	archived	Dec 14 2010 12:26PM	Jan 15 2011 12:07AM	N	Weisskopf
12	702511	13203	ACIS-S	NONE	16.000000	16.046587	ULASJ1120+0641	archived	Dec 13 2010 12:51PM	Feb 4 2011 12:08PM	D	Simpson
12	401291	13171	ACIS-S	NONE	4.000000	3.755348	1RXSJ192430.2+51014	archived	Oct 20 2010 9:21AM	Nov 7 2010 7:58AM	D	Liu
12	401290	13170	ACIS-S	NONE	4.000000	3.961600	1RXSJ194016.3+46325	archived	Oct 20 2010 9:21AM	Nov 7 2010 2:06PM	D	Liu
12	401289	13169	ACIS-S	NONE	3.000000	2.965220	1RXSJ192607.1+50525	archived	Oct 20 2010 9:20AM	Nov 12 2010 4:16PM	D	Liu
12	401288	13168	ACIS-S	NONE	3.000000	2.962514	1RXSJ190822.7+38510	archived	Oct 20 2010 9:20AM	Nov 12 2010 7:57PM	D	Liu
12	401287	13167	ACIS-S	NONE	3.000000	2.960000	1RXSJ191016.9+39295	archived	Oct 20 2010 9:20AM	Nov 7 2010 6:52AM	D	Liu
12	401286	13166	ACIS-S	NONE	3.000000	2.752000	1RXSJ193239.6+38251	archived	Oct 20 2010 9:20AM	Nov 4 2010 9:49PM	D	Liu
12	401285	13165	ACIS-S	NONE	3.000000	2.758400	1RXSJ192630.6+41331	archived	Oct 20 2010 9:20AM	Nov 4 2010 10:50PM	D	Liu
12	401284	13164	ACIS-S	NONE	2.000000	2.097700	1RXSJ194759.9+41311	archived	Oct 20 2010 9:20AM	Nov 14 2010 3:12AM	D	Liu
12	401283	13163	ACIS-S	NONE	2.000000	2.097586	1RXSJ191438.6+50285	archived	Oct 20 2010 9:20AM	Nov 7 2010 1:05PM	D	Liu
12	401282	13161	ACIS-S	HETG	30.000000	30.074000	EXO1745-248	archived	Oct 15 2010 12:44PM	Oct 24 2010 11:03AM	D	Bhattacharyya
12	501540	13154	ACIS-S	NONE	10.000000	10.000000	CrabNebula	archived	Oct 7 2010 11:57AM	Apr 28 2011 6:40AM	N	Weisskopf
12	501539	13153	ACIS-S	NONE	10.000000	10.000000	CrabNebula	archived	Oct 7 2010 11:57AM	Apr 21 2011 11:25PM	N	Weisskopf
12	501538	13152	ACIS-S	NONE	10.000000	10.000000	CrabNebula	archived	Oct 7 2010 11:57AM	Apr 16 2011 8:45AM	N	Weisskopf
12	501537	13151	ACIS-S	NONE	10.000000	10.000000	CrabNebula	archived	Oct 7 2010 11:57AM	Apr 14 2011 2:32PM	N	Weisskopf
12	501536	13150	ACIS-S	NONE	10.000000	10.000000	CrabNebula	archived	Oct 7 2010 11:57AM	Apr 13 2011 11:32PM	N	Weisskopf
12	501535	13149	ACIS-S	NONE	15.000000	15.459500	XTEJ1810-197	archived	Oct 7 2010 10:30AM	Oct 25 2010 4:19AM	D	Bernardini
12	501534	13148	ACIS-S	NONE	30.000000	30.009912	SGR0418+5729	archived	Oct 6 2010 4:04PM	Nov 29 2010 6:10AM	N	Rea
12	501533	13147	ACIS-S	NONE	5.000000	5.000000	Crab	archived	Oct 5 2010 4:26PM	Nov 28 2010 11:17AM	N	ferrigno
12	501532	13146	ACIS-S	NONE	5.000000	5.000000	Crab	archived	Oct 5 2010 4:26PM	Oct 28 2010 5:58PM	N	ferrigno
11	501531	13139	ACIS-S	NONE	5.000000	5.000000	CrabNebula	archived	Sep 23 2010 3:29PM	Sep 28 2010 5:21AM	N	Weisskopf
11	401281	13122	ACIS-S	NONE	10.000000	10.026400	ESO243-49HLX-1	archived	Sep 1 2010 9:49AM	Sep 6 2010 10:40PM	D	Farrell
11	401145	12314	ACIS-S	HETG	6.000000	6.000000	CygX-1	archived	Jul 14 2010 10:31AM	Jul 24 2010 5:38PM	N	McClintock
11	401144	12313	ACIS-S	HETG	6.000000	6.072000	CygX-1	archived	Jul 14 2010 10:31AM	Jul 22 2010 4:39PM	N	McClintock
11	501371	12312	ACIS-S	NONE	30.000000	30.009198	SGR0418+5729	archived	Jul 12 2010 10:28AM	Jul 23 2010 3:16PM	N	Rea
11	401141	12235	ACIS-S	HETG	20.000000	20.079600	CirX-1	archived	Jun 29 2010 5:24PM	Jul 4 2010 5:22AM	N	D'A
09	900939	12234	ACIS-I	NONE	53.000000	49.800438	ChandraDeepFieldS	archived	Jun 25 2010 4:49PM	Jul 22 2010 8:13PM	4	Tananbaum
09	900939	12233	ACIS-I	NONE	35.000000	36.043659	ChandraDeepFieldS	archived	Jun 25 2010 4:48PM	Jul 16 2010 10:52AM	4	Tananbaum
09	900939	12232	ACIS-I	NONE	34.000000	33.329777	ChandraDeepFieldS	archived	Jun 25 2010 4:45PM	Jul 18 2010 8:09PM	4	Tananbaum
09	900939	12231	ACIS-I	NONE	25.000000	25.047959	ChandraDeepFieldS	archived	Jun 23 2010 11:40AM	Jul 12 2010 3:49AM	4	Tananbaum
09	900939	12230	ACIS-I	NONE	38.000000	34.254918	ChandraDeepFieldS	archived	Jun 20 2010 2:29PM	Jul 11 2010 4:18AM	4	Tananbaum
11	501369	12229	ACIS-S	NONE	15.000000	15.037309	GRB100615A	archived	Jun 16 2010 3:07PM	Jun 21 2010 3:52AM	N	Levan
09	900939	12227	ACIS-I	NONE	55.000000	55.043411	ChandraDeepFieldS	archived	Jun 10 2010 12:06PM	Jul 14 2010 9:28PM	4	Tananbaum
09	900938	12223	ACIS-I	NONE	102.000000	102.041441	ChandraDeepFieldS	archived	May 26 2010 4:55PM	Jun 13 2010 1:21AM	4	Tananbaum
09	900938	12222	ACIS-I	NONE	31.000000	31.049146	ChandraDeepFieldS	archived	May 26 2010 4:10PM	Jun 5 2010 3:09AM	4	Tananbaum
11	501368	12221	ACIS-S	NONE	10.000000	10.065300	XTEJ1810-197	archived	May 21 2010 11:36AM	Jun 7 2010 3:29AM	D	Bernardini
09	900938	12220	ACIS-I	NONE	48.900000	48.768154	ChandraDeepFieldS	archived	May 18 2010 8:29AM	Jun 18 2010 1:16PM	4	Tananbaum
09	900938	12219	ACIS-I	NONE	34.200000	34.106014	ChandraDeepFieldS	archived	May 18 2010 8:20AM	Jun 6 2010 4:49PM	4	Tananbaum
09	900938	12218	ACIS-I	NONE	89.200000	89.142158	ChandraDeepFieldS	archived	May 12 2010 5:03PM	Jun 11 2010 10:33AM	4	Tananbaum
09	900936	12213	ACIS-I	NONE	62.100000	62.098441	ChandraDeepFieldS	archived	Apr 28 2010 3:10PM	May 17 2010 2:55PM	4	Tananbaum
11	300283	12203	HRC-S	LETG	5.000000	5.181632	KTEri	archived	Apr 9 2010 2:19PM	Apr 21 2010 11:03AM	N	Drake
09	900937	12138	ACIS-I	NONE	39.000000	39.044418	ChandraDeepFieldS	archived	Mar 30 2010 8:19AM	Apr 18 2010 1:16PM	4	Tananbaum
09	900937	12137	ACIS-I	NONE	94.000000	94.010314	ChandraDeepFieldS	archived	Mar 30 2010 8:19AM	Apr 16 2010 9:10AM	4	Tananbaum
09	900937	12135	ACIS-I	NONE	63.400000	63.357678	ChandraDeepFieldS	archived	Mar 25 2010 3:35PM	Apr 6 2010 9:50AM	4	Tananbaum
09	900937	12129	ACIS-I	NONE	78.200000	78.160096	ChandraDeepFieldS	archived	Mar 17 2010 10:54AM	Apr 3 2010 3:40PM	4	Tananbaum
09	900936	12128	ACIS-I	NONE	23.100000	23.104259	ChandraDeepFieldS	archived	Mar 9 2010 4:02PM	Mar 27 2010 1:28PM	4	Tananbaum
11	401138	12127	ACIS-S	HETG	25.000000	23.167750	4U1608-52	archived	Mar 8 2010 4:25PM	Mar 15 2010 4:46AM	N	Ozel
09	900936	12123	ACIS-I	NONE	25.100000	25.118041	ChandraDeepFieldS	archived	Mar 4 2010 3:45PM	Mar 21 2010 8:23AM	4	Tananbaum
11	300277	12102	HRC-S	LETG	25.000000	23.244182	UScorpii	archived	Jan 28 2010 12:11PM	Feb 14 2010 11:56AM	N	Orio
11	300276	12101	HRC-S	LETG	5.000000	5.158825	KTEri	archived	Jan 26 2010 9:26AM	Feb 6 2010 6:43AM	N	Drake
11	300275	12100	HRC-S	LETG	5.000000	5.181375	KTEri	archived	Jan 26 2010 9:26AM	Jan 31 2010 10:43PM	N	Drake
11	300274	12097	HRC-S	LETG	15.000000	15.183582	KTEri	archived	Jan 20 2010 12:33PM	Jan 23 2010 10:01PM	N	Ness
11	702317	12087	ACIS-S	NONE	3.000000	3.061700	Q0957+561	archived	Dec 22 2009 2:14PM	Jun 23 2010 11:29PM	N	Goicoechea
11	702316	12086	ACIS-S	NONE	3.000000	3.062981	Q0957+561	archived	Dec 22 2009 2:13PM	Jun 10 2010 10:14AM	N	Goicoechea
11	702315	12085	ACIS-S	NONE	3.000000	3.061700	Q0957+561	archived	Dec 22 2009 2:13PM	May 25 2010 11:08PM	N	Goicoechea
11	702314	12084	ACIS-S	NONE	3.000000	3.182400	Q0957+561	archived	Dec 22 2009 2:13PM	May 15 2010 4:53AM	N	Goicoechea
11	702313	12083	ACIS-S	NONE	3.000000	3.151800	Q0957+561	archived	Dec 22 2009 2:12PM	Apr 27 2010 1:21PM	N	Goicoechea
11	702312	12082	ACIS-S	NONE	3.000000	3.182400	Q0957+561	archived	Dec 22 2009 2:12PM	Apr 13 2010 1:14PM	N	Goicoechea
11	702311	12081	ACIS-S	NONE	3.000000	3.170500	Q0957+561	archived	Dec 22 2009 2:11PM	Mar 29 2010 9:43PM	N	Goicoechea
11	702310	12080	ACIS-S	NONE	3.000000	3.126300	Q0957+561	archived	Dec 22 2009 2:11PM	Mar 15 2010 12:00PM	N	Goicoechea
11	702309	12079	ACIS-S	NONE	3.000000	3.150100	Q0957+561	archived	Dec 22 2009 2:11PM	Mar 3 2010 2:58PM	N	Goicoechea
11	702308	12078	ACIS-S	NONE	3.000000	3.182400	Q0957+561	archived	Dec 22 2009 2:10PM	Feb 18 2010 6:43AM	N	Goicoechea
11	702307	12077	ACIS-S	NONE	3.000000	3.185800	Q0957+561	archived	Dec 22 2009 2:10PM	Feb 1 2010 12:50AM	N	Goicoechea
11	702306	12076	ACIS-S	NONE	3.000000	3.060000	Q0957+561	archived	Dec 22 2009 1:57PM	Jan 17 2010 12:56PM	N	Goicoechea
10	401137	12067	ACIS-S	HETG	11.000000	11.081250	1A0535+262	archived	Dec 15 2009 1:14PM	Dec 31 2009 2:19AM	D	Reynolds
10	401137	12066	ACIS-S	HETG	9.000000	8.917250	1A0535+262	archived	Dec 10 2009 2:59AM	Dec 28 2009 11:08AM	D	Reynolds
09	900936	12055	ACIS-I	NONE	81.800000	81.749978	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	May 15 2010 5:35PM	4	Tananbaum
09	900939	12054	ACIS-I	NONE	62.000000	61.810778	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	Jul 9 2010 12:02PM	4	Tananbaum
09	900939	12053	ACIS-I	NONE	75.000000	69.009060	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	Jul 5 2010 3:30AM	4	Tananbaum
09	900939	12052	ACIS-I	NONE	112.600000	111.875500	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	Jun 15 2010 4:32PM	4	Tananbaum
09	900938	12051	ACIS-I	NONE	58.000000	58.044247	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	Jun 10 2010 11:57AM	4	Tananbaum
09	900938	12050	ACIS-I	NONE	30.000000	30.048259	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	Jun 3 2010 7:03AM	4	Tananbaum
09	900938	12049	ACIS-I	NONE	88.000000	88.088925	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	May 28 2010 7:18PM	4	Tananbaum
09	900937	12048	ACIS-I	NONE	140.000000	139.932947	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	May 23 2010 7:26AM	4	Tananbaum
09	900937	12047	ACIS-I	NONE	10.300000	10.276459	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	Apr 12 2010 1:47PM	4	Tananbaum
09	900937	12046	ACIS-I	NONE	79.000000	79.056119	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	Apr 8 2010 8:31AM	4	Tananbaum
09	900937	12045	ACIS-I	NONE	101.000000	101.037949	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	Mar 28 2010 4:58PM	4	Tananbaum
09	900936	12044	ACIS-I	NONE	100.800000	100.842837	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	Mar 23 2010 11:55AM	4	Tananbaum
09	900936	12043	ACIS-I	NONE	131.300000	131.294013	ChandraDeepFieldS	archived	Nov 24 2009 3:21PM	Mar 18 2010 1:58AM	4	Tananbaum
10	200656	12009	ACIS-S	NONE	25.000000	24.473600	V838Mon	archived	Oct 13 2009 10:58AM	Jan 12 2010 8:44AM	N	Kastner
10	401125	11803	HRC-I	NONE	10.000000	10.156982	ESO243-49HLX-1	archived	Aug 10 2009 5:46PM	Aug 17 2009 12:41PM	N	Farrell
10	401124	11802	ACIS-S	NONE	5.000000	5.035200	NGC6440	archived	Aug 4 2009 6:03PM	Aug 10 2009 8:26AM	N	Heinke
10	501174	10929	ACIS-I	NONE	20.000000	20.134400	PSRJ1622-4950	archived	Jul 8 2009 9:03AM	Jul 10 2009 7:43AM	3	Rea
10	701973	10921	ACIS-S	NONE	5.000000	5.046400	2XMMJ130200.1+27465	archived	Jun 3 2009 12:08PM	Jun 27 2009 3:28AM	N	Watson
10	401066	10919	HRC-I	NONE	1.000000	1.175675	ESO243-49HLX-1	archived	May 29 2009 1:38PM	Jul 4 2009 2:15PM	N	Farrell
10	401065	10907	ACIS-S	NONE	20.000000	18.448100	GROJ1655-40	archived	Apr 17 2009 5:40PM	Jun 8 2009 2:46AM	N	Gallo
09	200569	10845	ACIS-S	NONE	40.000000	40.134400	ZCMa	archived	Dec 18 2008 11:19AM	Dec 28 2008 10:48PM	N	Stelzer
09	200568	10826	HRC-I	NONE	5.000000	4.978425	51Peg	archived	Nov 17 2008 8:51AM	Dec 6 2008 12:52PM	N	Schmitt
09	200568	10825	ACIS-S	NONE	5.000000	4.982400	51Peg	archived	Nov 17 2008 8:45AM	Dec 6 2008 11:21AM	N	Schmitt
09	401051	10574	HRC-I	NONE	5.000000	5.162669	XTEJ1701-407	archived	Aug 18 2008 3:29PM	Aug 26 2008 8:24PM	D	Kaplan
09	501152	10573	ACIS-S	NONE	10.000000	10.152500	GRB080307	archived	Aug 14 2008 5:07PM	Sep 22 2008 8:36AM	N	Page
09	401050	10571	HRC-I	NONE	1.000000	1.183875	VPuppis	archived	Aug 7 2008 2:56PM	Sep 1 2008 1:40AM	N	Maccarone
09	400934	9883	ACIS-S	NONE	10.000000	10.198400	XMMUJ005510.7-37385	archived	Jun 25 2008 2:22AM	Jul 8 2008 9:26PM	N	Kong
09	400933	9882	ACIS-S	NONE	30.000000	30.180000	AXJ1754.2-2754	archived	Jun 24 2008 3:23PM	Jul 15 2008 12:30AM	D	Keek
09	501018	9862	ACIS-S	NONE	30.000000	30.147200	GRB080503	archived	May 16 2008 4:13PM	May 25 2008 6:28PM	N	Butler
09	501017	9853	ACIS-S	NONE	30.000000	30.175400	GRB080503	archived	May 5 2008 9:16PM	May 7 2008 7:35PM	N	Butler
09	400932	9850	HRC-I	NONE	2.000000	2.186069	XTEJ1719-291	archived	Apr 15 2008 8:53AM	Apr 27 2008 6:34PM	D	Sala
09	701771	9814	ACIS-S	NONE	10.000000	9.907200	SDSSJ0952+2143	archived	Jan 23 2008 8:44AM	Feb 5 2008 4:43PM	N	Komossa
09	400931	9805	ACIS-S	NONE	5.000000	5.175000	M81	archived	Dec 19 2007 2:43PM	Dec 21 2007 6:54PM	D	Jonker
09	501014	9799	ACIS-S	NONE	21.500000	21.569800	SN2007on	archived	Dec 12 2007 3:41PM	Dec 27 2007 1:35AM	D	Roelofs
09	501014	9798	ACIS-S	NONE	18.500000	18.544200	SN2007on	archived	Dec 5 2007 3:21PM	Dec 24 2007 11:15AM	D	Roelofs
09	200526	9769	ACIS-I	NONE	30.000000	30.150559	NGC2264	archived	Nov 9 2007 4:15PM	Mar 28 2008 3:02PM	N	Micela
09	200526	9768	ACIS-I	NONE	30.000000	28.154200	NGC2264	archived	Nov 9 2007 4:08PM	Mar 12 2008 6:10PM	N	Micela
08	100071	9763	ACIS-S	NONE	10.000000	10.179200	Comet17P/Holmes	archived	Oct 29 2007 1:32PM	Oct 31 2007 4:21PM	N	Dennerl
08	100071	9762	ACIS-S	NONE	10.000000	10.188800	Comet17P/Holmes	archived	Oct 29 2007 1:32PM	Oct 31 2007 1:26PM	N	Dennerl
08	100071	9755	ACIS-S	NONE	10.000000	10.137600	Comet17P/Holmes	archived	Oct 26 2007 4:43PM	Oct 31 2007 10:31AM	N	Dennerl
08	900737	9718	ACIS-I	NONE	51.000000	50.030737	ChandraDeepFieldS	archived	Sep 19 2007 3:00PM	Oct 3 2007 2:12PM	N	Tananbaum
08	900737	9596	ACIS-I	NONE	115.400000	113.372872	ChandraDeepFieldS	archived	Sep 10 2007 3:32PM	Nov 4 2007 4:30AM	N	Tananbaum
08	900737	9593	ACIS-I	NONE	48.000000	47.045600	ChandraDeepFieldS	archived	Sep 5 2007 12:11PM	Sep 22 2007 8:49PM	N	Tananbaum
08	400928	9584	HRC-I	NONE	2.000000	2.184531	M15	archived	Aug 27 2007 11:51AM	Sep 5 2007 3:23PM	N	Heinke
08	501009	9579	ACIS-I	NONE	20.000000	19.709759	SN2007gr	archived	Aug 21 2007 1:16PM	Aug 29 2007 1:52AM	N	Soderberg
08	900737	9578	ACIS-I	NONE	40.000000	39.084800	ChandraDeepFieldS	archived	Aug 20 2007 4:20PM	Oct 30 2007 10:53PM	N	Tananbaum
08	900737	9575	ACIS-I	NONE	112.400000	110.133372	ChandraDeepFieldS	archived	Aug 20 2007 4:18PM	Oct 27 2007 6:09AM	N	Tananbaum
08	900737	8597	ACIS-I	NONE	61.000000	60.068618	ChandraDeepFieldS	archived	Aug 7 2007 3:31PM	Oct 17 2007 7:23AM	N	Tananbaum
08	900737	8596	ACIS-I	NONE	118.000000	116.640477	ChandraDeepFieldS	archived	Aug 7 2007 3:31PM	Oct 24 2007 1:46PM	N	Tananbaum
08	900737	8595	ACIS-I	NONE	118.000000	116.950436	ChandraDeepFieldS	archived	Aug 7 2007 3:31PM	Oct 19 2007 2:35PM	N	Tananbaum
08	900737	8594	ACIS-I	NONE	151.200000	143.272414	ChandraDeepFieldS	archived	Aug 7 2007 3:31PM	Nov 1 2007 12:10PM	N	Tananbaum
08	900737	8593	ACIS-I	NONE	51.000000	50.145559	ChandraDeepFieldS	archived	Aug 7 2007 3:31PM	Oct 6 2007 2:22AM	N	Tananbaum
08	900737	8592	ACIS-I	NONE	88.000000	87.785596	ChandraDeepFieldS	archived	Aug 7 2007 3:31PM	Oct 22 2007 12:36PM	N	Tananbaum
08	900737	8591	ACIS-I	NONE	46.000000	46.034877	ChandraDeepFieldS	archived	Aug 7 2007 3:31PM	Sep 20 2007 5:41AM	N	Tananbaum
08	400691	8564	ACIS-I	NONE	11.200000	11.152000	SWIFTJ1756.9-2508	archived	Jun 19 2007 12:29PM	Jul 6 2007 1:44AM	N	DiSalvo
08	400690	8562	ACIS-S	HETG	10.000000	10.152500	SWIFTJ195509.6+2614	archived	Jun 12 2007 1:01PM	Jun 14 2007 6:17PM	D	KANBACH
08	400689	8556	HRC-I	NONE	7.000000	7.180382	CirX-1	archived	Apr 27 2007 3:09PM	May 16 2007 9:11PM	D	Jonker
08	400688	8547	HRC-I	NONE	43.000000	43.290108	CirX-1	archived	Mar 30 2007 1:52PM	Apr 21 2007 5:32AM	D	Jonker
08	600649	8524	ACIS-S	NONE	30.000000	30.041600	GRB070125	archived	Feb 22 2007 9:56AM	Mar 5 2007 9:49PM	N	Frail
08	500822	8518	ACIS-S	NONE	3.000000	3.043200	SN2005kd	archived	Jan 30 2007 2:09PM	Mar 4 2007 2:54PM	N	Pooley
08	701583	8517	ACIS-S	NONE	5.000000	5.153200	M87	archived	Jan 26 2007 3:19PM	Mar 22 2007 4:06AM	N	Harris
08	701582	8516	ACIS-S	NONE	5.000000	5.159200	M87	archived	Jan 26 2007 3:19PM	Mar 19 2007 10:38AM	N	Harris
08	701581	8515	ACIS-S	NONE	5.000000	5.177600	M87	archived	Jan 26 2007 3:19PM	Mar 14 2007 2:43PM	N	Harris
08	701580	8514	ACIS-S	NONE	5.000000	4.929200	M87	archived	Jan 26 2007 3:19PM	Mar 12 2007 11:52AM	N	Harris
08	701579	8513	ACIS-S	NONE	5.000000	5.182800	M87	archived	Jan 26 2007 3:19PM	Feb 24 2007 3:16AM	N	Harris
08	701578	8512	ACIS-S	NONE	5.000000	5.185600	M87	archived	Jan 26 2007 3:19PM	Feb 21 2007 11:58PM	N	Harris
08	701577	8511	ACIS-S	NONE	5.000000	5.185600	M87	archived	Jan 26 2007 3:19PM	Feb 18 2007 10:23PM	N	Harris
08	701576	8510	ACIS-S	NONE	5.000000	5.183600	M87	archived	Jan 26 2007 3:19PM	Feb 15 2007 9:37AM	N	Harris
08	500821	8508	HRC-I	NONE	2.000000	2.159931	1RXSJ141256.0+79220	archived	Jan 19 2007 12:55PM	Feb 18 2007 6:05PM	D	Rutledge
08	500820	8506	ACIS-S	NONE	20.000000	20.182000	PSRJ1647-4552	archived	Jan 8 2007 1:10PM	Feb 2 2007 7:26PM	N	Woods
07	500817	8480	HRC-I	NONE	1.000000	1.149025	RBS1774(1RXSJ214303	archived	Nov 6 2006 2:27PM	Nov 26 2006 10:15PM	D	Zane
07	200460	8474	ACIS-I	NONE	10.000000	9.753600	LDN1415	archived	Oct 30 2006 11:32AM	Nov 18 2006 2:41AM	N	Kastner
07	500816	8473	ACIS-S	NONE	30.000000	30.124800	SN2006gy	archived	Oct 30 2006 11:20AM	Nov 14 2006 8:57PM	N	Pooley
07	500815	8457	ACIS-S	NONE	10.000000	9.961600	SN2006jc	archived	Oct 16 2006 12:14PM	Nov 4 2006 6:23AM	N	Immler
07	500814	8455	ACIS-S	NONE	15.000000	15.186750	PSRJ1647-4552	archived	Oct 12 2006 12:50PM	Oct 28 2006 7:19AM	D	Kas
07	400680	8273	ACIS-I	NONE	21.600000	20.030359	LSI+61303	archived	Sep 8 2006 3:29PM	Oct 25 2006 10:32PM	N	Perez-Torres
07	600607	7373	ACIS-S	NONE	7.000000	7.184000	XMMUJ132218.3-16424	archived	Jul 12 2006 5:56PM	Jul 31 2006 3:41AM	N	Miniutti
07	400561	7335	ACIS-S	NONE	10.000000	9.376000	PSRB1931+24	archived	May 5 2006 2:30PM	Jul 20 2006 3:01PM	D	Rea
07	100067	7334	ACIS-S	NONE	4.000000	4.182400	Comet73P/Schwassman	archived	May 2 2006 2:32PM	May 23 2006 10:34AM	N	Wolk
07	100066	7333	ACIS-S	NONE	4.000000	4.182400	Comet73P/Schwassman	archived	May 2 2006 2:32PM	May 23 2006 9:19AM	N	Wolk
07	100065	7332	ACIS-S	NONE	4.000000	4.185600	Comet73P/Schwassman	archived	May 2 2006 2:32PM	May 23 2006 8:03AM	N	Wolk
07	100064	7331	ACIS-S	NONE	4.000000	4.185600	Comet73P/Schwassman	archived	May 2 2006 2:32PM	May 23 2006 6:48AM	N	Wolk
07	100063	7330	ACIS-S	NONE	4.000000	4.105600	Comet73P/Schwassman	archived	May 2 2006 2:32PM	May 23 2006 5:33AM	N	Wolk
07	300179	7298	HRC-S	LETG	20.000000	20.126132	RSOph	archived	Mar 3 2006 1:28PM	Jun 4 2006 12:25PM	N	Starrfield
07	300178	7297	HRC-S	LETG	10.000000	9.505082	RSOph	archived	Mar 3 2006 1:28PM	Apr 20 2006 5:43PM	N	Starrfield
07	300177	7296	HRC-S	LETG	10.000000	10.152882	RSOph	archived	Mar 3 2006 1:28PM	Mar 24 2006 12:40PM	N	Starrfield
07	300172	7280	ACIS-S	HETG	10.000000	10.075000	RSOph	archived	Feb 14 2006 11:50AM	Feb 26 2006 3:36PM	N	Starrfield
07	500693	7277	ACIS-S	NONE	15.000000	14.998400	SN2005ke	archived	Feb 7 2006 9:31AM	Feb 19 2006 11:11AM	N	Immler
07	500692	7276	HRC-I	NONE	1.000000	1.112125	IGRJ15359-5750	archived	Feb 6 2006 12:40PM	Mar 28 2006 4:54AM	N	Israel
07	500691	7275	HRC-I	NONE	1.000000	1.122631	IGRJ18048-1455	archived	Feb 6 2006 12:40PM	Mar 28 2006 4:10AM	N	Israel
07	500690	7274	HRC-I	NONE	1.000000	1.097006	IGRJ17513-2011	archived	Feb 6 2006 12:40PM	Mar 28 2006 3:40AM	N	Israel
07	500689	7273	HRC-I	NONE	1.000000	1.095981	IGRJ17488-3253	archived	Feb 6 2006 12:40PM	Mar 28 2006 3:07AM	N	Israel
07	400559	7272	HRC-I	NONE	2.000000	2.135331	SWIFTJ1626.6-5156	archived	Feb 2 2006 3:13PM	Feb 21 2006 6:28AM	N	Homan
07	400558	7269	ACIS-S	NONE	1.000000	1.161600	HD109962	archived	Jan 23 2006 1:03PM	Feb 2 2006 2:14PM	N	Walter
06	500685	7241	ACIS-S	NONE	50.000000	50.179190	SN2005gj	archived	Nov 29 2005 4:53PM	Dec 11 2005 5:26PM	N	Pooley
05	800555	7225	ACIS-I	NONE	2.000000	2.045959	MACS1720.3+3536	archived	Nov 9 2005 3:10PM	Nov 27 2005 3:12AM	N	Allen
06	300171	7186	ACIS-S	HETG	50.000000	50.155000	RTCru	archived	Oct 5 2005 2:19PM	Oct 19 2005 10:41AM	N	Sokoloski
06	200372	6375	HRC-I	NONE	5.000000	5.150881	AlphaCentauri	archived	Aug 31 2005 11:31AM	Dec 17 2006 4:58AM	N	AYRES
06	200371	6374	HRC-I	NONE	5.000000	5.157031	AlphaCentauri	archived	Aug 31 2005 11:31AM	May 12 2006 6:31PM	N	AYRES
06	200370	6373	HRC-I	NONE	5.000000	5.187781	AlphaCentauri	archived	Aug 31 2005 11:31AM	Oct 21 2005 2:59AM	N	AYRES
06	400472	6354	ACIS-S	NONE	20.000000	19.043960	GRB050709	archived	Jul 19 2005 11:34AM	Jul 25 2005 9:03PM	N	Frail
06	400470	6298	HRC-I	NONE	5.000000	4.767531	SAXJ1808.4-3658	archived	Jun 7 2005 9:38AM	Jun 20 2005 11:25PM	N	Chakrabarty
06	400469	6297	ACIS-S	HETG	15.000000	14.344000	SAXJ1808.4-3658	archived	Jun 6 2005 3:27PM	Jun 12 2005 2:32AM	N	Galloway
06	500603	6284	ACIS-S	NONE	30.000000	29.788040	SN2005bx	archived	May 6 2005 3:24PM	Jul 30 2005 11:11AM	N	Filippenko
06	701180	6278	ACIS-I	NONE	3.500000	3.638000	IGRJ19473+4452	archived	Apr 20 2005 2:33PM	Jul 31 2005 9:32AM	N	Sunyaev
06	701179	6277	ACIS-I	NONE	3.500000	3.759572	IGRJ13091+1137	archived	Apr 20 2005 2:33PM	Jul 25 2005 10:25AM	N	Sunyaev
06	701178	6276	ACIS-I	NONE	3.500000	3.260449	IGRJ12391-1612	archived	Apr 20 2005 2:33PM	Jul 25 2005 11:45AM	N	Sunyaev
06	701177	6275	ACIS-I	NONE	3.500000	3.260799	IGRJ12026-5349	archived	Apr 20 2005 2:33PM	Jun 16 2005 6:10AM	N	Sunyaev
06	701176	6274	ACIS-I	NONE	3.500000	3.676799	IGRJ11085-5100	archived	Apr 20 2005 2:33PM	Jul 1 2005 3:58AM	N	Sunyaev
06	701175	6273	ACIS-I	NONE	3.500000	3.707715	IGRJ10252-6829	archived	Apr 20 2005 2:33PM	Jul 30 2005 9:24AM	N	Sunyaev
06	701174	6272	ACIS-I	NONE	3.500000	3.257599	IGRJ07563-4137	archived	Apr 20 2005 2:33PM	Jun 16 2005 4:46AM	N	Sunyaev
06	701173	6271	ACIS-I	NONE	3.500000	3.459199	IGRJ05007-7047	archived	Apr 20 2005 2:33PM	Jun 16 2005 3:25AM	N	Sunyaev
06	500601	6269	ACIS-S	NONE	20.000000	20.184090	GRB050412	archived	Apr 14 2005 10:32AM	Apr 17 2005 9:43AM	N	Berger
06	400468	6261	ACIS-S	NONE	10.000000	10.180800	PSRJ1638-4725	archived	Mar 14 2005 10:52AM	May 4 2005 7:47PM	N	McLaughlin
05	500600	6260	ACIS-S	NONE	10.000000	10.140790	GCRTJ1745-3009	archived	Mar 10 2005 3:52PM	May 1 2005 12:47AM	D	Hyman
06	400467	6259	ACIS-S	NONE	5.000000	5.169599	HESSJ1826-148	archived	Mar 10 2005 3:26PM	Apr 13 2005 3:01AM	N	Funk
06	500599	6251	HRC-S	NONE	30.000000	27.149430	SGR1806-20	archived	Feb 22 2005 3:08PM	Apr 22 2005 7:03PM	D	Kouveliotou
06	701172	6227	ACIS-S	NONE	10.000000	10.323190	NGC3690	archived	Feb 8 2005 11:54AM	Feb 14 2005 4:53AM	N	Nandra
06	500598	6224	ACIS-I	NONE	20.000000	19.059190	SGR1806-20	archived	Jan 27 2005 5:35PM	Feb 9 2005 7:25AM	1	Fox
06	500597	6207	ACIS-S	NONE	30.000000	29.100500	SGR1806-20	archived	Jan 18 2005 10:13AM	Feb 8 2005 10:54PM	1	Rea
06	200363	6204	ACIS-S	NONE	5.000000	5.136400	V1118Ori	archived	Jan 18 2005 9:48AM	Jan 26 2005 3:24AM	D	Audard
06	400447	6181	ACIS-S	NONE	15.000000	14.182800	IGRJ00291+5934	archived	Dec 17 2004 5:25PM	Feb 6 2005 1:45PM	N	Jonker
06	400446	6180	ACIS-S	NONE	10.000000	9.894359	IGRJ00291+5934	archived	Dec 17 2004 5:25PM	Jan 14 2005 12:11AM	N	Jonker
06	400445	6179	ACIS-S	NONE	5.000000	5.185200	IGRJ00291+5934	archived	Dec 17 2004 5:25PM	Jan 1 2005 9:24PM	N	Jonker
05	800557	6172	ACIS-I	NONE	30.000000	30.144270	MACS1621.6+3810	archived	Nov 30 2004 9:54AM	Dec 25 2004 10:04PM	N	Allen
05	500591	6129	ACIS-I	NONE	20.000000	19.508000	GRB040912	archived	Sep 13 2004 1:18PM	Sep 21 2004 11:18AM	N	Ricker
05	500590	6128	ACIS-I	NONE	20.000000	18.168000	GRB040912	archived	Sep 13 2004 1:18PM	Sep 15 2004 10:24PM	N	Ricker
05	800560	6112	ACIS-I	NONE	10.000000	9.510799	MACS1427.2+4407	archived	Aug 24 2004 2:41PM	Feb 12 2005 2:19AM	N	Allen
05	800559	6111	ACIS-I	NONE	50.000000	50.157877	MACS0744.9+3927	archived	Aug 24 2004 2:41PM	Dec 3 2004 9:25PM	N	Allen
05	800558	6110	ACIS-I	NONE	70.000000	64.042810	MACS1311.0-0311	archived	Aug 24 2004 2:41PM	Apr 20 2005 12:23AM	N	Allen
05	800557	6109	ACIS-I	NONE	40.000000	38.046250	MACS1621.6+3810	archived	Aug 24 2004 2:41PM	Dec 11 2004 2:31PM	N	Allen
05	800556	6108	ACIS-I	NONE	40.000000	40.169750	MACS0329.7-0212	archived	Aug 24 2004 2:41PM	Dec 6 2004 6:18AM	N	Allen
05	800555	6107	ACIS-I	NONE	38.000000	34.332410	MACS1720.3+3536	archived	Aug 24 2004 2:41PM	Nov 22 2005 9:35PM	N	Allen
05	800554	6106	ACIS-I	NONE	40.000000	35.770890	MACS0159.8-0849	archived	Aug 24 2004 2:41PM	Dec 4 2004 12:14PM	N	Allen
05	800553	6105	ACIS-I	NONE	40.000000	37.770350	MACS0011.7-1523	archived	Aug 24 2004 2:41PM	Jun 28 2005 11:51AM	N	Allen
05	800552	6104	ACIS-I	NONE	10.000000	9.737000	Abell2204	archived	Aug 24 2004 2:41PM	Sep 20 2004 11:42AM	N	Allen
05	800551	6103	ACIS-I	NONE	10.000000	10.406000	PKS0745-191	archived	Aug 24 2004 2:41PM	Sep 24 2004 12:35AM	N	Allen
05	800550	6102	ACIS-I	NONE	10.000000	10.127000	Abell478	archived	Aug 24 2004 2:41PM	Sep 13 2004 5:15PM	N	Allen
05	800549	6101	ACIS-I	NONE	10.000000	10.050190	Abell2029	archived	Aug 24 2004 2:41PM	Dec 17 2004 3:50AM	N	Allen
05	500585	6098	ACIS-I	NONE	5.000000	4.707000	HESSJ1303-631	archived	Aug 18 2004 9:57AM	Sep 25 2004 6:02PM	D	Halpern
05	500508	5365	ACIS-S	NONE	10.000000	10.163000	GRB040812	archived	Aug 13 2004 12:06PM	Aug 22 2004 10:12AM	N	Kouveliotou
05	500507	5364	ACIS-S	NONE	10.000000	10.175000	GRB040812	archived	Aug 13 2004 12:06PM	Aug 17 2004 7:28AM	N	Kouveliotou
05	600412	5360	ACIS-I	NONE	5.000000	5.174000	CXOGCJ174540.0-2900	archived	Aug 3 2004 5:00PM	Aug 28 2004 12:21PM	N	Baganoff
04	100052	5352	HRC-I	NONE	4.700000	4.657000	Moon	archived	Jul 13 2004 3:11PM	Jul 28 2004 1:30AM	N	Drake
04	100052	5351	HRC-I	NONE	5.600000	5.471000	Moon	archived	Jul 13 2004 3:11PM	Jul 27 2004 11:13PM	N	Drake
04	100052	5327	HRC-I	NONE	5.600000	5.638000	Moon	archived	May 12 2004 1:59PM	Jun 2 2004 10:58AM	N	Drake
05	100053	5326	ACIS-S	NONE	3.300000	3.471000	Comet2001Q4(NEAT)	archived	May 3 2004 2:15PM	May 12 2004 8:58PM	D	Lisse
05	100053	5325	ACIS-S	NONE	3.300000	3.484000	Comet2001Q4(NEAT)	archived	May 3 2004 2:14PM	May 12 2004 7:55PM	D	Lisse
04	100052	5324	HRC-I	NONE	5.640000	5.772000	Moon	archived	Apr 23 2004 2:22PM	May 4 2004 7:00AM	N	Drake
05	100053	5321	ACIS-S	NONE	3.400000	3.558000	Comet2001Q4(NEAT)	archived	Apr 16 2004 2:05PM	May 12 2004 6:50PM	D	Lisse
05	500506	5314	ACIS-S	NONE	30.000000	30.156000	GRB031203	archived	Mar 17 2004 5:29PM	Apr 18 2004 11:59AM	D	Kouveliotou
04	100052	5312	HRC-I	NONE	5.600000	5.679000	Moon	archived	Mar 15 2004 2:11PM	Jun 2 2004 8:41AM	N	Drake
04	100052	5311	HRC-I	NONE	5.640000	5.521000	Moon	archived	Mar 15 2004 2:05PM	May 4 2004 4:36AM	N	Drake
05	200298	5308	ACIS-S	NONE	5.000000	4.963000	IRAS05436-0007	archived	Feb 19 2004 6:43PM	Mar 22 2004 12:35AM	N	Kastner
05	200297	5307	ACIS-S	NONE	5.000000	5.561000	IRAS05436-0007	archived	Feb 19 2004 6:43PM	Mar 7 2004 1:41AM	N	Kastner
05	500505	5306	ACIS-S	NONE	15.000000	14.758000	SN2001em	archived	Feb 9 2004 3:39PM	Apr 4 2004 7:41PM	N	Pooley
05	500504	5305	HRC-S	LETG	35.000000	35.705000	RXJ0720.4-3125	archived	Feb 9 2004 3:38PM	Feb 27 2004 4:53AM	N	Vink
05	701014	5302	ACIS-S	NONE	30.000000	31.121000	NGC4395	archived	Jan 30 2004 8:22AM	Apr 11 2004 1:28AM	N	Moran
05	701013	5301	ACIS-S	NONE	30.000000	29.730000	NGC4395	archived	Jan 30 2004 8:22AM	Apr 10 2004 3:06AM	N	Moran
05	500503	5298	ACIS-S	NONE	25.000000	21.848000	GRB031203	archived	Jan 13 2004 11:16AM	Jan 22 2004 9:34PM	N	Kulkarni
05	300145	5293	HRC-S	LETG	40.000000	41.953000	MiraAB	archived	Dec 19 2003 11:52AM	Jan 11 2004 2:09PM	D	Karovska
05	300144	5292	HRC-S	LETG	10.000000	10.308000	V4743Sgr	archived	Dec 18 2003 5:07PM	Feb 28 2004 1:31AM	N	Starrfield
05	400376	5291	ACIS-S	NONE	10.000000	10.137000	PSRJ0737-3039	archived	Dec 18 2003 4:54PM	Jan 18 2004 7:56PM	1	McLaughlin
04	500500	5247	HRC-I	NONE	5.000000	4.871000	IGRJ16316-4028	archived	Oct 31 2003 1:24PM	Jan 18 2004 1:07PM	D	Foschini
04	500499	5246	ACIS-S	NONE	25.000000	25.509000	SN2003jd	archived	Oct 31 2003 1:20PM	Nov 10 2003 7:08PM	N	Watson
04	500498	5240	HRC-I	NONE	3.000000	2.884000	XTEJ1810-197	archived	Oct 9 2003 2:54PM	Nov 1 2003 3:26PM	N	Israel
04	200237	4455	ACIS-S	NONE	20.000000	19.898000	EtaCar	archived	Aug 14 2003 12:21PM	Aug 28 2003 5:53PM	S	Corcoran
04	500415	4454	HRC-I	NONE	3.000000	2.833000	XTEJ1810-197	archived	Aug 12 2003 2:22PM	Aug 27 2003 10:43PM	N	Gotthelf
04	500413	4449	ACIS-S	NONE	20.000000	18.435000	SN2002ic	archived	Aug 4 2003 2:52PM	Aug 11 2003 9:40PM	D	Hughes
04	500412	4443	ACIS-S	NONE	25.000000	25.125000	SGR1806-20	archived	Jul 21 2003 6:54PM	Aug 3 2003 12:13PM	D	Woods
04	400324	4439	ACIS-S	HETG	10.000000	9.987000	XTEJ1814-338	archived	Jun 6 2003 4:18PM	Jun 20 2003 2:12AM	D	Chakrabarty
04	800375	4438	ACIS-S	NONE	30.000000	29.136000	RCS0439.6-2905	archived	May 12 2003 2:31PM	Jun 6 2003 6:17AM	D	Bautz
04	400323	4434	ACIS-S	NONE	47.000000	47.051000	IGRJ16358-4726	archived	Apr 10 2003 4:23PM	Apr 21 2003 3:49AM	D	Kouveliotou
04	500411	4432	ACIS-S	LETG	100.000000	98.100000	GRB030328	archived	Mar 28 2003 10:14AM	Mar 29 2003 3:05AM	N	Ricker
04	400322	4426	HRC-S	NONE	3.000000	2.824000	XTEJ1807-294	archived	Feb 27 2003 3:35PM	Mar 10 2003 8:34AM	D	MARKWARDT
04	500410	4425	ACIS-S	NONE	40.000000	40.172000	GRB030226	archived	Feb 26 2003 3:15PM	Feb 27 2003 5:14PM	N	Pedersen
04	400321	4424	ACIS-S	NONE	10.000000	10.687000	XTEJ1908+094	archived	Feb 20 2003 2:41PM	May 14 2003 1:51AM	D	Jonker
04	400320	4423	ACIS-S	NONE	5.000000	5.150000	XTEJ1908+094	archived	Feb 20 2003 2:41PM	Apr 19 2003 3:14PM	D	Jonker
04	400319	4422	ACIS-S	NONE	5.000000	5.212000	XTEJ1908+094	archived	Feb 20 2003 2:41PM	Mar 24 2003 12:07AM	D	Jonker
04	400318	4420	ACIS-S	HETG	75.000000	76.220000	GX339-4	archived	Feb 12 2003 1:59PM	Mar 17 2003 8:05PM	D	Miller
04	500409	4417	ACIS-S	NONE	30.000000	30.415000	SN2003L	archived	Jan 30 2003 7:05PM	Feb 10 2003 3:59AM	N	Kulkarni
03	100038	4410	HRC-I	NONE	1.000000	1.120000	EARTH	archived	Dec 4 2002 4:43PM	Feb 7 2003 1:23AM	D	Gladstone
03	500408	4409	ACIS-S	NONE	30.000000	30.431000	GRB021004	archived	Nov 17 2002 12:28PM	Nov 25 2002 5:51PM	N	Sako
03	500407	4405	ACIS-S	NONE	10.000000	10.115000	SN2002HI	archived	Nov 7 2002 8:46PM	Dec 10 2002 5:45PM	N	Lewin
03	500406	4404	ACIS-S	NONE	30.000000	30.335000	SN2002HH	archived	Nov 7 2002 8:42PM	Nov 25 2002 8:58AM	N	Lewin
03	500405	4381	ACIS-S	HETG	80.000000	88.130000	GRB021004	archived	Oct 4 2002 12:41PM	Oct 5 2002 8:58AM	N	Harrison
03	500404	4364	ACIS-S	HETG	80.000000	78.122000	GRB020813	archived	Aug 13 2002 5:56AM	Aug 13 2002 11:46PM	N	Ricker
03	600330	4360	ACIS-I	NONE	5.000000	4.969000	M31	archived	Aug 2 2002 9:52AM	Aug 11 2002 6:15PM	N	Primini
03	400316	4358	ACIS-I	NONE	5.000000	4.979000	TEVJ2032+4130	archived	Aug 1 2002 5:35PM	Aug 11 2002 8:07PM	D	Butt
03	400315	4285	ACIS-S	NONE	5.000000	4.687000	V4641SGR	archived	Jul 19 2002 11:42AM	Aug 5 2002 4:16AM	D	Rupen
03	400270	3724	ACIS-S	HETG	30.000000	26.400000	CYGX-1	archived	Jul 15 2002 12:33PM	Jul 30 2002 5:42PM	N	Feng
03	400268	3672	ACIS-S	NONE	20.000000	18.255000	XTEJ1550-564	archived	May 29 2002 9:42AM	Jun 19 2002 9:17AM	D	Corbel
03	400267	3671	ACIS-S	NONE	5.000000	5.538000	1E1740.7-2942	archived	May 29 2002 9:33AM	Aug 17 2002 1:24PM	D	Heindl
03	400266	3670	ACIS-S	HETG	10.000000	10.140000	1E1740.7-2942	archived	May 29 2002 9:33AM	Jun 13 2002 7:29PM	D	Heindl
03	400265	3661	ACIS-S	LETG	20.000000	17.961000	XTEJ0929-314	archived	May 10 2002 3:51PM	May 15 2002 12:43AM	D	Chakrabarty
03	500298	3496	ACIS-S	NONE	25.000000	24.188000	SN2001IG	archived	Apr 30 2002 12:59PM	Jun 11 2002 6:20AM	N	Schlegel
03	500297	3495	ACIS-S	NONE	25.000000	23.734000	SN2001IG	archived	Apr 30 2002 12:59PM	May 21 2002 11:53PM	N	Schlegel
03	500296	3494	ACIS-S	NONE	15.000000	14.755000	XRF020427	archived	Apr 29 2002 3:42PM	May 14 2002 3:55AM	N	Fox
03	500295	3493	ACIS-S	NONE	15.000000	13.916000	XRF020427	archived	Apr 29 2002 3:42PM	May 6 2002 5:46AM	N	Fox
03	400247	3492	ACIS-S	NONE	5.000000	5.231000	RXJ170930.2-263927	archived	Apr 22 2002 3:15PM	Apr 23 2002 9:58PM	D	Jonker
03	400256	3490	ACIS-S	NONE	7.000000	7.648000	AQLX-1	archived	Apr 5 2002 12:13PM	Sep 3 2002 4:27PM	D	Rutledge
03	400255	3489	ACIS-S	NONE	7.000000	7.858000	AQLX-1	archived	Apr 5 2002 12:13PM	Aug 18 2002 8:19AM	D	Rutledge
03	400254	3488	ACIS-S	NONE	7.000000	7.172000	AQLX-1	archived	Apr 5 2002 12:13PM	Jul 22 2002 9:01PM	D	Rutledge
03	400253	3487	ACIS-S	NONE	7.000000	6.549000	AQLX-1	archived	Apr 5 2002 12:13PM	Jul 5 2002 3:45PM	D	Rutledge
03	400252	3486	ACIS-S	NONE	7.000000	7.151000	AQLX-1	archived	Apr 5 2002 12:13PM	Jun 11 2002 3:50AM	D	Rutledge
03	400251	3485	ACIS-S	NONE	7.000000	7.672000	AQLX-1	archived	Apr 5 2002 12:13PM	May 20 2002 7:41AM	D	Rutledge
03	400250	3484	ACIS-S	NONE	7.000000	7.160000	AQLX-1	archived	Apr 5 2002 12:13PM	May 4 2002 11:04PM	D	Rutledge
03	400249	3483	HRC-S	NONE	3.000000	2.976000	XTEJ1751-305	archived	Apr 5 2002 10:44AM	Apr 10 2002 4:31PM	D	MARKWARDT
03	400248	3481	ACIS-S	NONE	1.000000	1.133000	XTEJ1908+094	archived	Apr 3 2002 2:33PM	Apr 15 2002 5:39AM	N	Rupen
03	500294	3477	ACIS-S	NONE	20.000000	20.057000	GRB020321	archived	Mar 25 2002 11:28AM	Mar 31 2002 2:13AM	N	Fox
03	400246	3475	ACIS-S	NONE	5.000000	5.965000	RXJ170930.2-263927	archived	Mar 19 2002 3:24PM	Apr 10 2002 5:49PM	D	Jonker
03	400239	3464	ACIS-S	NONE	5.000000	5.147000	RXJ170930.2-263927	archived	Mar 11 2002 9:44AM	Apr 1 2002 12:43AM	D	Jonker
03	400238	3463	ACIS-S	NONE	8.477000	7.468038	RXJ170930.2-263927	archived	Mar 11 2002 9:44AM	Mar 18 2002 11:46AM	D	Jonker
03	400237	3462	ACIS-S	NONE	15.000000	14.210000	RXJ170930.2-263927	archived	Mar 11 2002 9:44AM	Mar 12 2002 1:52PM	D	Jonker
03	300090	3455	ACIS-S	HETG	35.000000	34.457000	GKPER	archived	Mar 6 2002 5:15PM	Apr 9 2002 3:06PM	D	Mauche
03	300089	3454	ACIS-S	HETG	35.000000	32.102000	GKPER	archived	Mar 6 2002 5:15PM	Mar 27 2002 9:49AM	D	Mauche
03	100034	3453	ACIS-S	NONE	12.000000	11.964000	Comet2002C1	archived	Mar 6 2002 2:20PM	Apr 15 2002 11:15PM	D	Dennerl
03	500292	3449	ACIS-S	NONE	3.000000	2.662000	SGR1900+14	archived	Feb 27 2002 4:34PM	Mar 11 2002 11:03AM	D	Woods
03	400236	3448	ACIS-S	NONE	30.000000	27.457000	XTEJ1550-564	archived	Feb 14 2002 12:00PM	Mar 11 2002 3:16PM	D	Corbel
03	100034	3447	ACIS-S	NONE	12.000000	11.718000	Comet2002C1	archived	Feb 14 2002 9:25AM	Apr 15 2002 1:52AM	D	Dennerl
03	500291	3441	ACIS-I	NONE	15.000000	14.672000	XRF011130	archived	Feb 4 2002 5:21PM	Feb 20 2002 10:18AM	N	Ricker
03	500287	3437	ACIS-I	NONE	10.000000	10.064000	GRB020127	archived	Jan 30 2002 1:31PM	Feb 11 2002 11:17AM	N	Fox
03	500286	3436	ACIS-I	NONE	10.000000	9.968000	GRB020127	archived	Jan 30 2002 1:31PM	Jan 31 2002 10:37PM	N	Fox
03	300087	3434	ACIS-S	NONE	5.000000	5.629000	IMNORMAE	archived	Jan 23 2002 12:58PM	Feb 4 2002 6:01PM	N	Starrfield
03	700612	3419	ACIS-S	NONE	100.000000	97.944000	MGJ0414+0534	archived	Dec 7 2001 4:55PM	Jan 9 2002 12:00AM	D	Chartas
03	100032	3412	ACIS-S	NONE	20.000000	20.122000	XRF011030	archived	Nov 15 2001 3:17PM	Nov 29 2001 11:09AM	D	Harrison
03	100031	3411	ACIS-S	NONE	50.000000	47.209000	XRF011030	archived	Nov 9 2001 12:48AM	Nov 9 2001 5:44PM	N	Harrison
02	400234	3407	ACIS-S	HETG	30.000000	30.070000	CYGX-1	archived	Oct 19 2001 10:35AM	Oct 28 2001 4:33PM	D	Cui
02	500285	3399	HRC-S	LETG	9.500000	9.318000	RXJ1856.5-3754	archived	Oct 1 2001 9:20AM	Oct 15 2001 11:59AM	N	Tananbaum
02	700608	3395	ACIS-S	NONE	30.000000	28.777000	MGJ0414+0534	archived	Sep 27 2001 10:49AM	Nov 9 2001 8:34AM	D	Chartas
02	500285	3382	HRC-S	LETG	100.500000	101.926000	RXJ1856.5-3754	archived	Sep 18 2001 4:46PM	Oct 8 2001 8:31AM	N	Tananbaum
02	500285	3381	HRC-S	LETG	170.000000	171.073000	RXJ1856.5-3754	archived	Sep 18 2001 4:46PM	Oct 12 2001 7:31PM	N	Tananbaum
02	500285	3380	HRC-S	LETG	170.000000	167.446000	RXJ1856.5-3754	archived	Sep 18 2001 4:43PM	Oct 10 2001 5:18AM	N	Tananbaum
02	400233	3360	ACIS-S	NONE	2.500000	2.641000	NGC6440	archived	Aug 15 2001 12:28PM	Aug 18 2001 8:23PM	N	in'tZand
02	700607	3359	ACIS-S	NONE	6.000000	5.760000	QSOJ0836+0054	archived	Aug 10 2001 4:26PM	Jan 29 2002 12:02PM	N	Brandt
02	700606	3358	ACIS-S	NONE	8.000000	8.262000	QSOJ1306+0356	archived	Aug 10 2001 4:26PM	Jan 29 2002 6:28AM	N	Brandt
02	700605	3357	ACIS-S	NONE	8.000000	8.057000	QSOJ1030+0524	archived	Aug 10 2001 2:46PM	Jan 29 2002 9:11AM	N	Brandt
02	300067	2514	ACIS-S	NONE	10.000000	10.179000	WZSGE	archived	Jul 31 2001 1:15PM	Sep 19 2001 1:56AM	N	Kuulkers
02	300066	2513	ACIS-S	NONE	10.000000	12.075000	WZSGE	archived	Jul 31 2001 1:15PM	Aug 22 2001 8:41AM	N	Kuulkers
02	300065	2512	ACIS-S	NONE	5.000000	4.910000	WZSGE	archived	Jul 31 2001 1:15PM	Aug 7 2001 5:47PM	N	Kuulkers
02	300061	2508	ACIS-S	NONE	5.000000	5.159000	WZSGE	archived	Jul 24 2001 6:25PM	Jul 29 2001 4:49PM	N	Wheatley
02	300059	2506	HRC-S	LETG	20.000000	19.984000	WZSGE	archived	Jul 24 2001 6:14PM	Aug 18 2001 8:07AM	N	Wheatley
02	300058	2505	HRC-S	LETG	20.000000	18.760000	WZSGE	archived	Jul 24 2001 6:14PM	Aug 6 2001 7:53PM	N	Wheatley
02	300057	2504	HRC-S	LETG	20.000000	19.950000	WZSGE	archived	Jul 24 2001 6:14PM	Jul 27 2001 2:44AM	N	Wheatley
02	300056	2492	ACIS-S	NONE	20.000000	19.885000	CIAQL	archived	Jul 6 2001 4:17PM	Aug 1 2001 12:52PM	D	Greiner
02	300054	2465	ACIS-S	NONE	2.000000	2.149000	CIAQL	archived	May 9 2001 12:29PM	Jun 1 2001 8:41PM	D	Greiner
02	500200	2459	ACIS-S	NONE	20.000000	18.896000	PSRJ1907+0919	archived	Apr 19 2001 11:22AM	Apr 30 2001 11:27PM	N	Kouveliotou
02	500199	2458	ACIS-S	NONE	20.000000	20.835000	SGR1900+14	archived	Apr 18 2001 7:19PM	Apr 22 2001 4:58AM	N	Kulkarni
02	700393	2454	ACIS-S	NONE	5.000000	4.500000	CIRCINUSGALAXY	archived	Apr 13 2001 1:53PM	May 2 2001 4:20PM	N	Matt
02	400164	2430	HRC-I	NONE	10.000000	9.889000	GRS1758-258	archived	Mar 9 2001 12:43PM	Mar 24 2001 7:43AM	D	Heindl
02	400163	2429	ACIS-S	HETG	30.000000	30.320000	GRS1758-258	archived	Mar 9 2001 12:43PM	Mar 24 2001 10:58AM	D	Heindl
02	400162	2428	ACIS-S	NONE	20.000000	20.400000	KS1731-260	archived	Mar 7 2001 3:25PM	Mar 27 2001 12:34AM	D	Wijnands
02	800178	2427	ACIS-S	NONE	20.000000	18.094000	PKS0745-191	archived	Mar 7 2001 10:46AM	Jun 16 2001 5:50AM	D	Fabian
02	500197	2424	ACIS-S	NONE	30.000000	29.923000	GRB010222	archived	Feb 22 2001 10:36AM	Feb 22 2001 10:28PM	D	Piro
02	400161	2415	ACIS-S	HETG	30.000000	30.146000	CYGNUSX-1	archived	Dec 16 2000 3:51PM	Jan 4 2001 6:20AM	D	Miller
02	900066	2409	ACIS-I	NONE	69.000000	69.895000	ChandraDeepFieldS	archived	Dec 5 2000 4:47PM	Dec 19 2000 4:12AM	N	GIACCONI
02	900066	2406	ACIS-I	NONE	31.000000	30.079000	ChandraDeepFieldS	archived	Dec 1 2000 2:25PM	Dec 10 2000 11:51PM	N	GIACCONI
02	200125	2338	ACIS-S	HETG	25.000000	24.838000	WR140	archived	Oct 27 2000 10:51AM	May 8 2001 8:01PM	D	Pollock
02	200124	2337	ACIS-S	HETG	50.000000	46.124000	WR140	archived	Oct 27 2000 10:51AM	Dec 29 2000 10:32AM	D	Pollock
01	300053	2336	ACIS-S	HETG	20.000000	19.222000	ZANDROMEDAE	archived	Oct 26 2000 3:36PM	Nov 13 2000 3:19PM	D	Charles
02	900066	2313	ACIS-I	NONE	132.000000	132.115000	ChandraDeepFieldS	archived	Sep 22 2000 10:04AM	Dec 21 2000 2:28AM	N	GIACCONI
02	900066	2312	ACIS-I	NONE	136.000000	125.323000	ChandraDeepFieldS	archived	Sep 22 2000 10:04AM	Dec 13 2000 3:47AM	N	GIACCONI
02	900066	2239	ACIS-I	NONE	132.000000	132.469000	ChandraDeepFieldS	archived	Aug 28 2000 4:08PM	Dec 23 2000 5:49PM	N	GIACCONI
01	400112	1846	ACIS-S	NONE	5.000000	4.630000	XTEJ1550-564	archived	Aug 7 2000 3:27PM	Sep 11 2000 5:10AM	D	Tomsick
01	400111	1845	ACIS-S	NONE	5.000000	5.164000	XTEJ1550-564	archived	Aug 7 2000 3:27PM	Aug 21 2000 9:08AM	D	Tomsick
01	700266	1715	HRC-S	LETG	20.000000	19.839000	MRK421	archived	May 8 2000 5:01PM	May 29 2000 5:53PM	N	Fruscione
01	700265	1714	ACIS-S	HETG	20.000000	19.830000	MRK421	archived	May 8 2000 5:01PM	May 29 2000 11:57AM	N	Fruscione
01	300041	1706	ACIS-S	HETG	60.000000	59.881000	EXHYA	archived	Apr 13 2000 3:23PM	May 18 2000 9:59AM	D	Howell
01	400110	1701	ACIS-S	LETG	30.000000	27.830000	XTEJ1118+480	archived	Apr 7 2000 3:32PM	Apr 18 2000 6:36PM	D	McClintock
01	700202	442	ACIS-S	NONE	5.000000	4.976000	NGC526A	archived	Mar 16 2000 9:26AM	Apr 23 2000 6:54AM	S	Wilson
01	400093	426	ACIS-S	HETG	20.000000	18.318000	CYGX-3	archived	Feb 16 2000 2:09PM	Apr 6 2000 8:17PM	N	McCollough
01	400092	425	ACIS-S	HETG	20.000000	21.654000	CYGX-3	archived	Feb 16 2000 2:09PM	Apr 4 2000 2:05PM	N	McCollough
01	300037	327	ACIS-S	NONE	5.000000	4.947000	2MASSJ06285693+7202	archived	Jan 20 2000 10:10AM	Feb 8 2000 4:18PM	D	DiStefano
01	500093	364	HRC-I	NONE	50.000000	48.159000	PSRB0833-45	archived	Jan 19 2000 11:30AM	Feb 21 2000 2:11AM	N	Helfand
01	300037	327	ACIS-S	NONE	5.000000	4.947000	2MASSJ06285693+7202	archived	Jan 19 2000 11:30AM	Feb 8 2000 4:18PM	D	DiStefano
01	570470	1520	ACIS-S	NONE	25.000000	24.035000	NGC3184	archived	Jan 19 2000 11:21AM	Feb 3 2000 11:00AM	3	Schlegel
01	100011	1465	HRC-S	LETG	23.150000	23.418000	JUPITER	archived	Oct 20 1999 1:31PM	Nov 26 1999 8:07PM	3	WAITE
01	100011	1464	HRC-S	LETG	14.760000	14.778000	JUPITER	archived	Oct 20 1999 1:30PM	Nov 26 1999 2:35PM	3	WAITE
01	100010	1463	ACIS-S	NONE	22.600000	22.364000	JUPITER	archived	Oct 20 1999 1:29PM	Nov 26 1999 2:10AM	3	WAITE

Canceled DDT Observations
Cycle	Sequence Number	ObsID	Instrument	Grating	Approved Exposure Time	Target	Status	PI Name

24	402520	28928	ACIS-S	NONE	0.100000	V404Cyg	canceled	Hynes
23	503447	27642	ACIS-S	NONE	0.000000	AT2022tsd	canceled	Ho
23	503446	27641	ACIS-S	NONE	0.000000	AT2022tsd	canceled	Ho
23	503445	27640	ACIS-S	NONE	0.000000	AT2022tsd	canceled	Ho
22	402291	24934	ACIS-S	HETG	40.000000	CenX-4	canceled	in'tZand
21	704253	24647	ACIS-S	NONE	30.000000	ESO253-G003	canceled	Payne
21	704252	24646	ACIS-S	NONE	30.000000	ESO253-G003	canceled	Payne
21	201346	23150	HRC-I	NONE	5.000000	Betelgeuse	canceled	Kashyap
21	201345	23149	HRC-I	NONE	5.000000	Betelgeuse	canceled	Kashyap
20	402116	22135	ACIS-S	NONE	15.000000	ZTF18abfzgpl	canceled	Ofek
17	201085	18820	ACIS-S	HETG	30.000000	Capella	canceled	Petre
17	201085	18819	ACIS-S	HETG	30.000000	Capella	canceled	Petre
15	401687	17560	ACIS-S	NONE	20.000000	CXOJ122518.6+144545	canceled	Heida
13	200829	14409	ACIS-S	NONE	8.000000	55Cnc	canceled	Wheatley
12	401296	13245	HRC-I	NONE	1.000000	MAXIJ1659-152	canceled	Jonker
09	900939	12311	ACIS-I	NONE	18.700000	ChandraDeepField-S	canceled	Tananbaum
09	900936	12214	ACIS-I	NONE	40.000000	ChandraDeepField-S	canceled	Tananbaum
08	900737	9577	ACIS-I	NONE	30.000000	ChandraDeepField-S	canceled	Tananbaum
08	900737	9576	ACIS-I	NONE	2.000000	ChandraDeepField-S	canceled	Tananbaum
07	200461	8475	ACIS-I	NONE	10.000000	L1415EXor	canceled	Kastner
07	300182	7301	ACIS-S	HETG	15.000000	RSOph	canceled	Starrfield
07	300181	7300	ACIS-S	HETG	15.000000	RSOph	canceled	Starrfield
07	300180	7299	HRC-S	LETG	20.000000	RSOph	canceled	Starrfield
06	500684	7192	ACIS-S	NONE	20.000000	GRB051022	canceled	Ricker
06	200365	6206	ACIS-S	NONE	8.333333	V1118Ori	canceled	Audard
06	200364	6205	ACIS-S	NONE	8.333333	V1118Ori	canceled	Audard
04	100052	5328	HRC-I	NONE	2.500000	Moon	canceled	Drake
04	100052	5313	HRC-I	NONE	4.700000	Moon	canceled	Drake
04	500414	4450	ACIS-S	NONE	20.000000	SN2002ic	canceled	Hughes
03	400269	3723	ACIS-S	NONE	30.000000	MACHO-99-BLG-22	canceled	Reynolds
03	500299	3497	ACIS-S	NONE	25.000000	SN2001IG	canceled	Schlegel
03	400245	3470	ACIS-S	NONE	10.000000	RXJ170930.2-263927	canceled	Jonker
03	400244	3469	ACIS-S	NONE	10.000000	RXJ170930.2-263927	canceled	Jonker
03	400243	3468	ACIS-S	NONE	10.000000	RXJ170930.2-263927	canceled	Jonker
03	400242	3467	ACIS-S	NONE	5.000000	RXJ170930.2-263927	canceled	Jonker
03	400241	3466	ACIS-S	NONE	5.000000	RXJ170930.2-263927	canceled	Jonker
03	400240	3465	ACIS-S	NONE	5.000000	RXJ170930.2-263927	canceled	Jonker
03	100033	3446	ACIS-S	NONE	8.000000	C/2002C1	canceled	Dennerl
03	500290	3440	ACIS-S	NONE	25.000000	SN2002AP	canceled	Schlegel
03	500289	3439	ACIS-S	NONE	25.000000	SN2002AP	canceled	Schlegel
03	500288	3438	ACIS-S	NONE	25.000000	SN2002AP	canceled	Schlegel
03	300088	3435	ACIS-S	NONE	25.000000	IMNORMAE	canceled	Starrfield
03	700614	3421	ACIS-S	NONE	30.000000	MGJ0414+0534	canceled	Chartas
03	700613	3420	ACIS-S	NONE	30.000000	MGJ0414+0534	canceled	Chartas
02	700611	3398	ACIS-S	NONE	30.000000	MGJ0414+0534	canceled	Chartas
02	700610	3397	ACIS-S	NONE	30.000000	MGJ0414+0534	canceled	Chartas
02	700609	3396	ACIS-S	NONE	30.000000	MGJ0414+0534	canceled	Chartas
01	100027	3379	ACIS-S	NONE	9.000000	COMET19P/BORRELLY	canceled	Dennerl
01	100027	3378	ACIS-S	NONE	9.000000	COMET19P/BORRELLY	canceled	Dennerl
01	100027	3377	ACIS-S	NONE	9.000000	COMET19P/BORRELLY	canceled	Dennerl
01	100027	2517	ACIS-S	NONE	9.000000	COMET19P/BORRELLY	canceled	Dennerl
02	300064	2511	ACIS-S	NONE	10.000000	WZSGE	canceled	Wheatley
02	300063	2510	ACIS-S	NONE	10.000000	WZSGE	canceled	Wheatley
02	300062	2509	ACIS-S	NONE	10.000000	WZSGE	canceled	Wheatley
02	300055	2466	ACIS-S	NONE	2.000000	CIAQL	canceled	Greiner
02	500202	2461	ACIS-S	NONE	5.000000	SGR1900+14	canceled	Kouveliotou
02	500201	2460	ACIS-S	NONE	5.000000	SGR1900+14	canceled	Kouveliotou
02	500198	2457	ACIS-S	NONE	20.000000	SGR1900+14	canceled	Kulkarni
01	400113	1847	ACIS-S	NONE	5.000000	XTEJ1550-564	canceled	Tomsick

Sequence Number: 601707

Title : Pinpointing the X-rays from an offset TDE candidate with Chandra
PI: Yao
Abstract: Offset tidal disruption events (TDEs) represent a novel pathway for
identifying massive black holes (MBHs) beyond galactic centers. They
probe MBH binaries and recoiling MBHs kicked by the gravitational
waves from MBH mergers. Using the Zwicky Transient Facility (ZTF)
optical time domain survey, we identified an off-nuclear transient
AT2024tvd, whose ZTF position is 1.24 +/- 0.30 arcsec from the nucleus
of its host galaxy. The optical and UV properties of AT2024tvd are
consistent with both a TDE and an exotic supernova. A possible X-ray
counterpart detected by XRT exhibits luminous, soft X-ray emission.
Here we request a 20ks Chandra observation to achieve sub-arcsec
spatial resolution and accurately determine the location of the X-ray
emission. If Chandra can confirm the association of this X-ray
transient with AT2024tvd, it would establish AT2024tvd as the first
confirmed off-nuclear TDE. This effort will advance our understanding
of MBH dynamics across diverse galactic environments.

Sequence Number: 503585

Title : Observing the birth of a stellar mass black hole in M31
PI: De
Abstract: Stellar mass black holes (BHs) form a corner stone of astrophysics;
yet there remains no observational consensus on how they form. The
majority are believed to form from the collapse of massive stellar
cores that fail to explode as a supernova, and instead implode into a
BH. However, identifying individual disappearing stars at
extragalactic distances remains a daunting task. Using archival data
from the NEOWISE survey, we have identified a faint MIR brightening of
a massive supergiant in the Andromeda galaxy, which subsequently has
faded dramatically in optical and bolometric luminosity. Modeling the
exquisitely rich archival dataset, we identify a failed supernova as
the most likely explanation. Here, we propose Chandra ACIS
observations in support of a once-in-a-lifetime opportunity to study a
failed SN in the nearest Milky Way-like galaxy, that will i)
conclusively establish the birth of a BH and ii) reveal the fallback
energetics and the physics of accretion onto the new-born BH.

Sequence Number: 503585

Sequence Number: 201823

Title : EP241021a, an Einstein Probe fast X-ray transient reconciling
different powerful explosive events?
PI: Jonker
Abstract: The origin of extra-galactic Fast X-ray Transients (FXTs) has remained
a mystery for much of the past 15 years since their first
serendipitous discovery in Chandra observations. Einstein Probe is
revolutionizing the field detecting FXTs with unique and very
different properties. Recently, a new FXT, EP241021a, without a
gamma-ray burst was discovered. An optical counterpart was quickly
found at a redshift of z=0.75. Interestingly, the light curve
evolution is unlike that of GRBs in either the optical or the X-ray.
The properties of EP241021a can be reconciled as a luminous fast blue
optical transient (LFBOT). However, a crucial piece of the puzzle, the
X-ray observations during the LFBOT peak and the late-time X-ray
evolution is currently still missing.

Sequence Number: 201822

Title : X-ray detection of the low-mass companion responsible for Betelgeuse's
long secondary period
PI: O'Grady
Abstract: We propose X-ray observations of Betelgeuse in order to detect the
recently proposed low-mass companion star, which is responsible for
the long secondary period discovered in Betelgeuse's optical
lightcurve. This companion was proposed independently by two new
publications in August 2024, and was not know prior to the Chandra
Cycle 26 Call for Proposals. Past Chandra observations, and X-ray
observations in general by every X-ray instrument all the way back to
Rosat in 1990, occurred either when the companion was eclipsed by
Betelgeuse or were too shallow to probe the companion's X-ray
emission. The companion will be visible again in December of this
year, and then not until 2027.

Sequence Number: 503590

Title : Calibrating the afterglow contribution and energetics of GRB 240825A
PI: Gompertz
Abstract: GRB 240825A has been activated as a target for JWST GO 6133, designed
to cleanly separate long-lived gamma-ray bursts driven by mergers and
collapsing stars by making spectroscopic confirmation or exclusion of
associated supernova with NIRSpec. We request two epochs of Chandra
observations to span the JWST observation window in order to measure
the contribution of the afterglow, which remains bright in Swift/XRT
monitoring. By measuring the flux and decay rate in the X-rays, where
the afterglow dominates, we will be able to separate the afterglow
light from the supernova light in optical and nIR.

These observations will provide vital context for the afterglow
properties in the limited 'clean' progenitor sample taken by JWST,
allowing us to search for discriminants between the two types of
long-lasting GRB. We will also search for a jet break, which will
enable us to measure the jet opening angle and calculate the
beaming-corrected energy release of the GRB.

Sequence Number: 503589

Sequence Number: 503588

Title : Chandra follow up of a cow-like FBOT
PI: MARGUTTI
Abstract: Fast and Blue Optical Transients (FBOTs) are a new class of
relativistic transients. Their large peak luminosities and extremely
fast evolution are not consistent with the expectations from standard
stellar explosions. Alternative scenarios include strong shock
interaction with a dense medium, or the presence of a central engine,
for example in the form of an accreting BH. Here we propose deep
Chandra follow-up observations of the X-ray detected FBOT AT2024wpp,
as part of a multi-wavelength campaign spanning the entire
electromagnetic spectrum. Our overarching goal is to advance our
understanding of the powering source of FBOTs, by constraining the
X-ray spectrum and the long-term X-ray temporal evolution of
AT2024wpp.

Sequence Number: 503587

Sequence Number: 503586

Sequence Number: 503585

Sequence Number: 705195

Title : High-resolution X-ray spectroscopy of Centaurus A with Chandra, XRISM,
and NuSTAR
PI: Bogensberger
Abstract: XRISM will observe Cen A in the week of July 29, for 160 ks. NuSTAR
will simultaneously observe it for 100 ks. Together, the XRISM/Resolve
and NuSTAR spectra will enable an unprecedented broad-band,
high-resolution investigation into the physical properties in the
nearest AGN. However, neither instrument is sensitive to soft X-rays,
and both have a low angular resolution, which causes the spectra to be
contaminated by the jet, X-ray binaries, and diffuse emission from the
galaxy. Both of these issues can be resolved by Chandra, and only by
Chandra. We seek 22 ks of Chandra/HETG spectroscopy taken within two
weeks of the simultaneous XRISM and NuSTAR observations, to accurately
measure the absorption, and determine the degree of contamination of
the AGN spectrum by non-nuclear sources. This will be essential for
determining the spectral continuum even to much higher energies, which
will also be vital for determining key spectral parameters in the
deeper XRISM and NuSTAR observations.

Sequence Number: 201740

Title : EP240414A, an Einstein Probe fast X-ray transient bridging Luminous
Fast Blue Optical Transients and Long Gam
PI: Jonker
Abstract: The origin of extra-galactic Fast X-ray Transients has remained a
mystery for much of the past 15 years since their first serendipitous
discovery in Chandra observations. Einstein Probe is revolutionizing
the field with many more new discoveries of FXTs than anticipated, and
of FXTs with unique properties. Recently, a new FXT, EP240414a,
without a gamma-ray burst was discovered. An optical counterpart was
quickly found and a redshift of z=0.4 was determined. Interestingly,
the light curve evolution is unlike that of a GRB in either the
optical or the X-ray. The properties of EP240414a seem to be an
amalgamation between some of those of long GRBs and that of a luminous
fast blue optical transient (LFBOT). However, a crucial piece of the
puzzle, the late-time X-ray evolution is currently still missing.

Sequence Number: 402525

Title : Detecting the X-ray Emission of the Black Hole Gaia BH3
PI: Pacucci
Abstract: A massive black hole (BH) of ~33 solar was recently discovered in a
binary system observed via Gaia's astrometry.
The system is at a distance of ~590 pc, and the orbital period of the
binary is ~11.6 years. This source was never observed in the X-rays.
Contrary to previous discoveries of dormant'' BHs by Gaia (e.g., Gaia
BH1), this BH may be detectable in the X-rays because 1) its mass is
significantly higher; 2) its companion is a giant star with
significantly larger stellar winds; 3) its relatively low distance,
similar to Gaia BH1.
We request 50 ks of Chandra DDT time to detect the X-ray emission from
Gaia BH3 caused by accretion from ISM and/or from the companion's
stellar winds, which we estimate at ~10^-14 erg/s/cm^2.
This source would be the first X-ray detected massive galactic BH. It
would unlock a monitoring campaign of its variability with
Chandra/XMM/Swift, and allow the study of a BH accreting in a
radiatively inefficient mode, which is a physics-rich topic.

Sequence Number: 503516

Title : Observing the Circumstellar Interaction of the 7 Mpc SN2024ggi
PI: Zimmerman
Abstract: The most common type of Supernovae (SNe) in the universe are Type II
SNe. However, SNe II with detected X-rays are scarce because they are
not bright X-ray emitters. Therefore only extremely nearby SNe are
bright enough to produce detailed X-ray lightcurves and spectra. Such
a SNe has very recently exploded in a very (7 Mpc) nearby galaxy -
SN2024ggi. We propose to obtain Chandea X-ray observations, measuring
the extended wind surrounding the progenitor star. These data will be
unique and are guaranteed to create significant scientific impact. See
attached science justification.

Sequence Number: 503515

Sequence Number: 300555

Title : High energy gratings spectroscopy of novae
PI: Sokolovsky
Abstract: (This is re-submission of the previously discussed DDT request
25308970 from 2024 March 15. The current Swift/XRT count rate for
V1723 Sco is 0.26 cts/s total and 0.088 cts/s in 0.3-2 keV range.) The
peculiar elemental abundances of nova ejecta reveal the composition of
the white dwarf hosting the eruption. Accurate abundances are crucial
for estimating the ejected mass from X-ray absorption. We propose a
30ks Chandra/HETG observation of V1723 Sco that unexpectedly reached
an exceptionally high level of shock-powered X-ray emission (0.3
Swift/XRT cts/s) on 2024-03-13, 33 days after the start of the
eruption. Being only the second classical nova (after V959 Mon)
observed to reach this brightness, V1723 Sco presents a unique
opportunity to perform grating spectroscopy of shocked nova ejecta and
address key questions about nova eruptions in general.

Sequence Number: 503514

Title : Precise localization of a peculiar fast X-ray transient
PI: Troja
Abstract: LXT240402A is a long duration X-ray transient possibly associated with
a gamma-ray burst GRB240402B. Its position lies close to a nearby
(z~0.045) galaxy, which has been suggested as the possible host
galaxy. The long duration, large offset and nearby distance are
reminiscent of the peculiar GRB230307A and GRB211211A, two nearby long
GRBs produced by the merger of two compact objects. Here we propose a
Chandra observation to cement the association between the X-ray
transient and its optical counterpart. The current error radius of 10
arcsec is not sufficient to rule out a chance alignment, only Chandra
subarcsec accuracy would allow us to robustly link the X-ray and
optical/nIR source, and identify this event as a peculiar transient in
the local universe.

Sequence Number: 705176

Title : Follow-up Observation of a Peculiar Long-term Soft X-ray Flare
Detected by the EP Mission
PI: Jin
Abstract: Einstein Probe (EP) is a recently launched X-ray mission with 3600
deg^2 lobster-eye FoV, aiming to discover new transients in 0.5-4 keV.
On March 11th 2024, EP detected a bright soft X-ray flare, namely
EP240222a, which was then found to have brightened for two months.
Preliminary multi-wavelength data analyses show that it is likely a
newly born off-center X-ray TDE, and probably involving an IMBH.
Additionally, EP240222a shows peculiar strong X-ray short-term
variability and tentative evidence of outflow absorption features,
both are rarely seen in TDEs. Thus EP240222a has a high scientific
importance for deeper exploration. Here we request a Chandra DDT
observation to quickly follow this newly discovered peculiar
transient. This observation is crucial for spatially confirming its
counterpart, as well as exploring its rare short-term variability and
outflows.

Sequence Number: 705175

Title : Confirming the X-ray counterpart to ZTF19acnskyy
PI: Hernandez-Garcia
Abstract: The early type galaxy SDSS1335+0728, which had exhibited no prior
optical variations during the previous two decades, began showing
significant nuclear variability in the Zwicky Transient Facility (ZTF)
alert stream in December 2019 (as ZTF19acnskyy). In February 2024,
more than four years after the first optical alert, the source started
showing X-ray emission. However at a distance of 6'' from ZTF19acnskyy
and with a position error of 3.6'', we cannot confirm that it is
related to the optical transient. We request Chandra data to resolve
the position of the X-ray source. If nuclear, we are probably
witnessing the turning-on of an active galactic nucleus (AGN) or an
exotic supermassive black hole transient; if off-nuclear, this could
be a wandering intermediate mass black hole or a very exotic
transient. If we confirm its AGN nature, it could represent the first
observations of an AGN while it is activating.

Sequence Number: 201735

Title : EP 240315A, the first counterpart to an Einstein Probe fast X-ray
transient
PI: Levan
Abstract: The first optical counterpart and first redshift measurement (z =
4.859) of an X-ray transient discovered by the Einstein Probe have
just been made. We propose a set of 4 urgent Chandra observations in
order to sample the light curve and spectral energy distribution of
this yet unknown transient. Is there a panchromatic afterglow powered
by
synchrotron emission as in GRBs? How does this afterglow decay? Is
there any evidence of late-time engine activity? If there is a
GRB-like decay, and if so, when does it steepen to show signs of any
jet-break which provides an opening angle and total energetics?

Sequence Number: 201734

Sequence Number: 402524

Title : Coordinated CXO/JWST observations of A0620-00
PI: Gallo
Abstract: Our team has upcoming Cycle 2 JWST observations of the quiescent black
hole X-ray binary (BHXB) A0620-00, which is accreting at nearly one
billionth of its Eddington luminosity. We are securing coordinated
(albeit not strictly simultaneous) coverage at virtually all other
wavelengths, yielding the highest-quality spectral energy distribution
of a BHXB ever assembled. This will enable us, for the first time, to
measure the integrated jet power, and confirm or disprove whether
quiescent BHXBs are indeed jet-dominated.

Sequence Number: 402524

Sequence Number: 402523

Title : Arcsec localization of the new X-ray transient SRGA J144459.2-604207
PI: Illiano
Abstract: SRGA J144459.2-604207 is a bright and new accreting millisecond pulsar
discovered in outburst on 2024 February 21 (ATel #16464). The best
source position has been so far determined using Swift/XRT at
RA=221.248375 DEC=-60.697972, with an associated uncertainty of 3.5
arcseconds (90% c.l; ATel #16471). These coordinates are however not
fully reliable, given the very high count-rate of the source (i.e.,
about 43 cts/s) and the subsequent pile-up impact. The ongoing efforts
to obtain multi-wavelength counterparts of the source have been so far
not conclusive. At least five optical sources have been reported
within the Swift/XRT position (ATel #16489). In addition, a radio
observation with ATCA has discovered a new bright radio source located
at an offset of 5.5 arcsec with respect to the current X-rays
coordinates. Improved and more accurate localization of the source is
fundamental to identify the multi-band counterpart(s) of the source
and to guide the upcoming observing campaigns.

Sequence Number: 503513

Title : GRB 240218A
PI: Pena
Abstract: Long duration Gamma-ray Bursts (GRBs) are extremely luminous objects
that can be seen across the universe. At z = 6.78, GRB 240218A has
already been detected in X-ray, optical, and radio wavelengths and
provides a rare opportunity to probe the early universe, tracing star
formation and potentially discovering the first generation of stars!
Multi wavelength observations of GRBs are critical to constraining the
kinetic energy and the progenitor environment. In particular, late
time X-ray observations are essential for deriving the true energetics
of an ultra-relativistic jet. We propose Chandra observations of GRB
240218A to get tighter constraints on the jet break time to determine
the true burst energetics.

Sequence Number: 201730

Title : Simultaneous observations of HR 1099 with Chandra and XRISM
PI: Miller
Abstract: We request a 30-ksec Chandra ACIS-S/HETG observation of HR 1099 to
overlap with any portion of a 200-ksec XRISM observation planned for
6-10 March 2024 primarily to calibrate the Resolve gain scale at
intermediate energies (2-3 keV).

Sequence Number: 201730

Sequence Number: 705150

Title : Simultaneous Chandra and XRISM Spectroscopy of NGC 4151
PI: Miller
Abstract: XRISM is currently scheduled to observe NGC 4151 on Dec 27, 2023, for
45 ks. This is the first of four planned XRISM exposures; the rest
will likely be taken in late April 2024. Below 4 keV, the HETGS
offers superior resolution to the Resolve calorimeter. Simultaneous -
or at least contemporaneous observations - will provide the best
opportunity to study the variable absorption and winds in NGC 4151,
the nature and origin of the narrow Fe K line, and to search for
relativistic disk reflection. NuSTAR will also observe NGC 4151
providing coverage of the ionizing continuum out to 79 keV, but no
coverage below 3 keV. Chandra spectroscopy is essential for
characterizing the lines and absorption edges at low energy that
ultimately shape the continuum through the Fe K band, where the
strongest outflows and relativistic disk reflection are evident.
[Submitted on behalf of the XRISM team; additional communication with
the Director includes some privileged information.]

Sequence Number: 705150

Sequence Number: 705140

Title : TRACKING THE ULX POPULATION ACTIVITY IN NGC 1068 DURING THE IXPE
OBSERVATION
PI: Marinucci
Abstract: We propose two observations of the nuclear region of NGC 1068, 10 ks
each, during the IXPE (Imaging X-ray Polarimeter Explorer) pointing of
the source, in January 2024. We aim at monitoring the flux levels of
the Ultra Luminous X-ray sources (ULXs) within the Field of View of
NGC 1068, which might potentially contaminate the measurement of the
polarization signal from the Active
Galactic Nucleus (AGN). With its superior angular resolution, Chandra
is the only X-ray observatory on orbit which will allow us to
disentangle the emission of the ULXs from the one of the AGN. Since
these contaminating sources vary on timescales of weeks, we require an
ACIS-S observation at the beginning and
another one at the end of the IXPE pointing (03-29 January 2024).

Sequence Number: 705139

Sequence Number: 705136

Title : Microlensing in HE0230-2130
PI: Pooley
Abstract: Image A of the quadruply lensed quasar HE 0230-2130 has experienced a
sudden brightening due to microlensing: 0.4 magnitudes in past 60
days. Such events are uncommon, and multi-wavelength observations of
the rise and peak can set strong constraints on the size of the
emission regions in the quasar since microlensing is sensitive to the
size of the source. If this brightening is due to an eventual caustic
crossing, such a high-magnification event could resolve the central
structure of the quasar on nano-arcsecond scales. We will continue to
monitory the source nightly for at least the next month to follow its
optical evolution. We propose four Chandra observations over the same
period to follow its X-ray evolution. The X-rays are expected to
evolve faster to peak higher than the optical. The sub-arcsecond
separation of images A and B require Chandra's resolution. This is a
rare opportunity that should not be missed.

Sequence Number: 402522

Title : Chandra/IXPE DDT Observations of Cygnus X-3
PI: McCollough
Abstract: Cygnus X-3 (Cyg X-3) is a well-known microquasar which has a rich
X-ray line spectrum. The X-ray polarization mission IXPE is planning
to make new observations of Cyg X-3 in the latter half the month of
November 2023. Previous IXPE observations have shown Cyg X-3 to be a
highly polarized source in the X-ray (~20%). The polarization
variations as function of energy show a sudden drop in polarization in
the Fe line region (6-7 keV). In this proposal we seek to make
Chandra HETG spectra during the new IXPE observations. We will do a
detailed comparison of Chandra and the polarization of the IXPE
spectra. We will also seek to compare and do an orbital phase analysis
of both spectra and polarization.

Sequence Number: 705138

Sequence Number: 705137

Sequence Number: 705136

Sequence Number: 705135

Sequence Number: 503512

Title : Unveiling the nature of a candidate multi-messenger supernova
PI: Stein
Abstract: High energy neutrinos were first discovered in 2013, but their origin
remains largely unknown. Supernovae have long been predicted to
produce high-energy neutrinos through CSM interaction, but there has
thus far been no observational evidence to support these theories.
However, in October 2023, optical follow-up of a neutrino revealed the
first candidate neutrino-SN association. AT2023uqf, a young
rapidly-evolving transient discovered during neutrino follow-up,
resembles an SN Ibn spectroscopically but the lightcurve resembles a
luminous fast blue optical transient. Spectroscopy confirms the
presence of CSM interaction, as required for neutrino production, and
a chance coincidence is disfavoured at 3 sigma significance.
Associations at this level are highly impactful in the field of
neutrino astronomy. We request Chandra observations to test for
LFBOT-like X-ray emission, which could confirm the presence of a
relativistic jet, and would be essential to inform neutrino emission
models.

Sequence Number: 503512

Sequence Number: 402519

Title : Chandra, JWST, and ALMA Observations of the Quiescent Black Hole
Binary V404 Cyg
PI: Hynes
Abstract: The quiescent black hole X-ray binary V404 Cyg will be observed with
JWST and ALMA. We propose to supplement these observations with
Chandra coverage. V404 Cyg exhibits an IR excess in Spitzer
observations above that expected from either the secondary star or the
accretion disk and proposed to originate from either a relativistic
jet or a circumbinary disk. The JWST-ALMA program is focused on
discriminating these possibilities as ALMA emission should come from
the jet only. Adding Chandra coverage would add information about the
accretion flow near the black hole. The joint Chandra-JWST-ALMA
observations would then probe the inflow-outflow connection and jet
formation close to the black hole at extremely low accretion rates,
and would be compared to predicted multiwavelength lightcurves from
models of internal shocks in jets. These observations when compared to
those from V404 Cyg in outburst would allow a study of jets spanning
five orders of magnitude dynamic range in luminosity.

Sequence Number: 402518

Title : Observing GRB 230812B - To understand Jet Physics for an Extremely
Bright GRB
PI: Pathak
Abstract: A complete understanding of the physics of GRB jets requires extended
broadband followup observations for detailed source modelling. In
typical GRBs, such inferences are hindered by limited observations,
usually obtained only in the early relatively bright phase of the
afterglow. The very bright GRB 230812B gives a unique opportunity to
obtain high-quality observations extending into late times, where
models remain poorly constrained. It is the brightest GRB for which
hard X-ray polarisation measurements are possible - which can be
completed only if parameters of the jet are inferred from afterglow
data. Chandra is the only instrument that can obtain late-time soft
X-ray data required. The goals of the proposal are to a) to measure
flux and spectroscopic properties of the afterglow at late times, (b)
to identify or constrain the existence of a jet break, and (c) to
leverage the high angular resolution of Chandra to quantify any
possible host galaxy contributions to the X-ray emission.

Sequence Number: 402518

Sequence Number: 402517

Sequence Number: 503452

Title : SN 2023ixf: A bright supernova in M101
PI: Chandra
Abstract: Supernova SN 2023ixf has exploded in a nearby galaxy M101 (d=6.4 Mpc),
discovered on 19 May at a magnitude 14.9. It is one of the closest
supernovae found in the past several decades. The optical spectra has
shown flash ionization features indicating of dense circumstellar
medium (CSM), which powers X-ray and radio emission in a supernova.
Thus we are nearly guaranteed to detect X-ray emission, which can
constrain shock energetics and CSM characteristics. As the supernova
is very young, it is expected to evolve fast. Thats why we request for
two epochs. This will provide understanding of circumstellar
interaction evolution with time, which is crucial since they are
connected to the stellar mass-loss at prior to the supernova. We are
also triggering our approved GMRT radio observations and requested for
for VLA DDT time in 2-25 GHz. Swift-XRT observations are approved for
this supernova. However, Chandra is superior to Swif
to provide accurate determination of column density.

Sequence Number: 402459

Title : TRACKING THE NE X ACCRETION DISK LINE EMISSION OF ULTRACOMPACT X-RAY
BINARY 4U 1626-67 ACROSS A TORQUE REVERSAL
PI: Ng
Abstract: We propose a 60 ks HETGS observation of the ultracompact X-ray binary
4U 1626-67 that will, for the first time, characterize the Ne X
accretion disk line emission so close in time to a torque reversal. 4U
1626-67 is an unusual ultracompact X-ray binary that hosts a highly
magnetized (B ~ 3x10^(12) G) slowly rotating pulsar (P ~ 7.7 s) and a
low-mass companion (M_c ~ 0.02x solar mass). It is one of the two low
mass X-ray binaries that has exhibited long-term torque reversals (the
other being GX 1+4). Since its discovery in the 1970s, it has
exhibited three torque reversals. The pulse profiles have very
different morphologies between the two spin states, suggesting
significant changes in the accretion geometry. Our proposed
observation will be the closest to a torque reversal of 4U 1626-67,
which will provide us the unique opportunity to track the evolution of
the Ne X line emission across a torque reversal episode and trace the
inner disk location.

Sequence Number: 402459

Sequence Number: 704945

Title : An X-ray view of the Scary Barbie
PI: Guolo
Abstract: AT2021lwx/ZTF20abrbeie, a.k.a Scary Barbie, is an ultra-luminous
optically discovered transient at z ~ 1 with no previously cataloged
host. It is the most energetic transient ever observed, showing a
single optical brightening by a factor >100 to a luminosity of 7 x
10^(45) erg s^(-1) and a total radiated energy of 1.5 x 10^(53) erg,
both greater than any known optical transient. Very little is known
about its X-ray emission and spectra, but the stacking of recent
Swift/XRT data reveals a detection at an X-ray luminosity > 10^(45)
erg s^(-1), which is brighter than any non-jetted transient. We have
obtained a long XMM observation and aim to use the high sensitivity
and low background of Chandra to track the spectral and luminosity
evolution of the source. We request two visits at +30 days and +80
days from this request, divided in 20ks and 30 ks, respectively.

Sequence Number: 503453

Title : Determining the jet collimation of the dirty fireball GRB candidate
AT2023lcr
PI: Martin-Carrillo
Abstract: AT2023lcr is a recently discovered fast-fading red transient with
multi-wavelength observations consistent with a typical long gamma-ray
burst (GRB) afterglow at redshift 1.0272. However, no gamma-ray prompt
emission was detected in the direction of the transient. GOTO
observations constrained the window of possible prompt emission
allowing gamma-ray missions to set tight limits on the gamma-ray
emission. Based on these observations, there are two leading possible
scenarios: an on-axis dirty fireball that had its prompt emission
choked or an off-axis GRB with a narrow jet whose prompt emission we
missed. In the case of the dirty fireball, low Lorentz factor implied
by the lack of GRB prompt emission also suggest a weaker jet
collimation. Here we propose to observe the X-ray afterglow of this
rare case of GRB to constrain its jet opening angle and distinguish
between these two models and measure its true energetics.

Sequence Number: 100228

Title : A Chandra and JWST view of M-dwarf rocky planet atmospheres
PI: Howard
Abstract: One out of four terrestrial planet atmospheres accessible to JWST
orbits a flaring M-dwarf. The X-ray light from these flares drives
variability in planetary atmospheres, breaking apart molecules,
causing atmospheric escape, and complicating interpretation of transit
spectra. Upcoming JWST observations of a rocky exoplanet orbiting the
M-dwarf flare star LTT 1445A provide a unique opportunity to probe the
effects of flares on the planet. These observations are part of the
approved JWST Cycle 1 large program 2512. LTT 1445 is a hierarchical
triple system of mid to late M-dwarfs, with 2 terrestrial planets
transiting the A component on 3.1 and 5.4 d periods. Both components
are confirmed flare stars, as new Chandra observations spatially
resolve A and BC, and observe frequent flares from each. Chandra will
detect ~1 flare in the SXR during the flare-affected period of JWST
observations. We request the first simultaneous X-ray and NIR
observation of activity on a rocky planet atmosphere.

Sequence Number: 503452

Sequence Number: 503451

Sequence Number: 704913

Title : Understanding the orbital evolution of the repeating partial tidal
disruption: J0456-20
PI: Liu
Abstract: Repeating flares from the centre of galaxies with recurrence times of
months to decades have been reported recently. The total number of
these events is still small, with four reported so far. They are best
explained as repeating partial tidal disruption events (pTDEs).
Compared to normal one-off TDEs, repeating pTDEs are particularly
valuable for studying the accretion process in supermassive black hole
(SMBH)-accreting systems, as multi-wavelength observations can be
efficiently scheduled at different flux level. In addition, they are
also the best candidates to explore the dynamics of tightly bound
stars around SMBHs beyond our own Galaxy. We request three Chandra
observations, i.e. 10ks each for the first two observations and 20ks
for the last observation, to accurately measure the X-ray variability
and precisely locate the position of one of the most well-studied
repeating pTDE candidate J0456-20 during its next flaring period.

Sequence Number: 402458

Title : Determining the True Energetics of one of the Brightest Gamma-ray
Bursts
PI: Fong
Abstract: GRB 230307A is a recently discovered long-duration gamma-ray burst
(GRB) and represents one of the brightest such events detected in over
50 years of observation. Based on ongoing multi-wavelength
observations, there are two exciting possibilities for this event: it
is the result of a massive star collapse at z>1 which spawned the most
energetic GRB to date, or it is a nearby neutron star merger with a
kilonova detection (the second event in this class). Despite its
gamma-ray brightness, its X-ray and optical afterglows are
comparatively faint requiring the sensitivity of Chandra to monitor
it. Here we propose to monitor the X-ray afterglow of the remarkable
GRB 230307A to constrain its opening angle and thus true energetics.

Sequence Number: 402458

Sequence Number: 704913

Sequence Number: 704912

Sequence Number: 402457

Title : Which Source is Active in Terzan 5?
PI: Heinke
Abstract: Many globular clusters contain multiple transient LMXBs, identified by
Chandra in e.g. NGC 6440, Liller 1, and Terzan 5. MAXI sees an
outburst from Terzan 5 (Atel 15917, at 89 mCrab), confirmed by Swift
(Atel 15919, Kennea+23), suggested to be Terzan 5 X-3, last seen in
2012. However, the Swift 3.5 error circle includes 5-6 other known
X-ray sources, and the redback MSP Ter 5 P (Bogdanov+21)--possibly a
transitional MSP (only 3 confirmed). We request Chandra to pinpoint
the outbursting LMXB. If we confirm Ter 5 X-3, we will establish its
recurrence time and thus average mass-transfer rate, crucial for
studies of crust and core cooling (e.g. Brown+2018). If it is a new
transient, it will enable e.g. a census of transient LMXBs, their
recurrence rates, the quiescent spectrum, & enable later IR follow-up
(e.g. 30-m class). Radio studies are proposed, but their angular
resolution is less (VLA is in B-config) and Terzan 5 is very complex
in the radio (Urquhart+2020), so Chandra is needed.

Sequence Number: 402456

Title : High Resolution Spectroscopy of the First Giant Outburst from LS V +44
17
PI: Reynolds
Abstract: The Be/XRB LSV +44 17 is undergoing a type-II outburst for the first
time, with a luminosity near the Eddington limit (fx ~ 3 crab, 15-50
keV). In a BeXRB accreting at Eddington luminosities, we expect the
accretion flow to thicken, accompanied by significant outflows e.g.,
Shakura & Sunyaev (1973). Studies of Be/XRBs promise the opportunity
to learn much about this mode of accretion.

X-ray spectroscopy provides a means to study the innermost regions of
the accretion flow
where the wind will originate. The unique high resolution X-ray
spectroscopy provided by
Chandra/HETGS in the iron K region is the only platform with which to
study disk winds.
Previously a ~3000 km/s outflow has been detected from the BeXRB
1A0535+262 at a
luminosity of 10% Eddington (Reynolds+ 2010). At higher luminosities
still, we may expect
a higher velocity outflow (Higginbottom+ 2019) and these models are
supported by the
discovery of a ~0.2c from Swift J0243.6+6124 (van den Eijnden+ 2019).

Sequence Number: 503450

Title : Discovery of 12.5 days periodic bumps in the late-time light curves of
a unique type Ic supernova
PI: Chen
Abstract: Neutron stars (NS) or stellar-mass black holes (BH) are thought to be
formed from massive star explosions. People have found indirect
evidence of many tens of stellar-mass BHs, mainly from systems
detected as X-ray transients. However, the immediate connection
between the newly born BH or NS and the supernova explosion has not
been directly observed.

We propose to observe a unique, the-first-of-its-kind supernova SN
2022jli which shows periodic bumps in the optical light curve. The
visible light periodicity is likely induced by an internal engine,
like a binary star in which at least one of the components is a
compact object. Since the visible light periodicity is likely
processed emission of high energy photons from accretion, X-ray
observation is critical for understanding the origin of the
periodicity.
Due to the X-ray background emission from the host galaxy, Chandra's
observation at sub-arcsec resolution is critical to detect the X-ray
emission from the system.

Sequence Number: 503449

Sequence Number: 503448

Sequence Number: 503444

Title : Discovery of Minute-timescale Flares in the Aftermath of a Cosmic
Explosion
PI: Ho
Abstract: Over the past week we detected minute-timescale optical flares with
supernova-like luminosities associated with a 100-day old transient at
z=0.256. Our discovery has no precedent, and the simplest explanation
is blazar-like activity, i.e., an on-axis relativistic jet powered by
a black hole. However, unlike in TDEs, this black hole would have to
be either stellar-mass or intermediate-mass. A basic prediction of the
blazar model is coincident X-ray flares. We request Chandra
observations within the next two weeks to search for the predicted
X-ray flares. Chandra is the only facility with the required
sensitivity.

Sequence Number: 503444

Sequence Number: 201611

Title : A red giant orbiting a black hole
PI: El-Badry
Abstract: We propose 20ks ACIS observations of a newly-discovered black hole +
red giant binary only 1 kpc from Earth. We identified the binary
through Gaia DR3 astrometry. Our spectroscopic follow-up has recently
validated the Gaia orbital solution and shown this object to be one of
only two high-probability black hole candidates among ~1 million
binary star orbital solutions published in DR3. The orbital period --
1270 days -- is much longer than that of any known black hole binary.
Nevertheless, accretion of the giant's wind by the BH will lead to
detectable X-rays for any radiative efficiency above 10^-4. The
periastron passage -- when the X-ray flux is expected to peak -- will
occur in February 2022. The next passage will not occur until 2026,
motivating rapid response now. These observations will enable prompt
publication of the 2nd unambiguous dormant black hole in the Milky Way
and offer good odds for X-ray detection of the BH with the lowest
known accretion rate.

Sequence Number: 402454

Title : Flux Limits on the Nearest Black Hole: Gaia BH1
PI: Rodriguez
Abstract: The Milky Way is thought to contain about 1e8 stellar mass black holes
(BHs). However, only ~20 BHs are dynamically confirmed. Almost all of
these are accreting from a companion and were discovered via X-rays.
By calculating astrometric orbits for ~ 1e5 binaries, the recent 3rd
Gaia data release yielded a single unambiguous dormant BH: Gaia BH1. A
bright (G=13.8), slowly-rotating G2 star orbits a 10 Msun BH with an
orbital period of 186 days, much longer than the periods of X-ray
binaries. At d=480 pc, the system is the closest known BH by a factor
of 3. This implies that although wide, dormant BHs are difficult to
detect, they are significantly more abundant than their accreting,
X-ray bright cousins. The G2 donor star ejects mass through winds that
should accrete onto the BH with an unknown efficiency. A deep Chandra
ACIS observation will constrain the accretion efficiency of this
system, thus probing the physics of accretion in this new and unique
population of BHs.

Sequence Number: 901855

Title : Mapping the dust along the line of sight to GRB221009A
PI: Heinz
Abstract: Bright X-ray transients can cause extended ring-like dust scattering
echoes in the Galactic plane. Tomography of these echoes allows
accurate distance measurements and studies of dust mineralogy and
distribution. GRB221009A was among the brightest bursts in recent
history and at a Galactic latitude of 4.25 degrees, has produced a
bright ring echo detected with Swift. We propose to follow up this
detection using Chandra to measure the distance to the dust clouds
along the line of sight with unprecedented accuracy and to perform
measurements of dust-to-gas ratios of different interstellar clouds by
matching the observed dust to CO data to be obtained from the IRAM 30m
dish. Only Chandra has the angular resolution to take advantage of how
narrow these rings are expected to be, given how short gamma ray
bursts typically are.

Sequence Number: 704875

Title : First Look at an Extremely Reddened Lensed Quasar Image
PI: Pooley
Abstract: We have discovered what is likely the most highly reddened lensed
quasar image, which has the potential to give what may be the best
reddening curve ever obtained for a z~0.5 galaxy. Lensing models
predict that the close pair of images (about 0.6 arcseconds apart)
should be comparable in brightness, but i band imaging with IMACS
reveals that one image is nearly 100 times fainter than the other of
the close pair. X-ray imaging is needed to determine what role
microlensing might play in the flux ratio anomaly and how much is due
to a dust lane in the lensing galaxy. A pointed ROSAT/PSPC caught the
object at the very edge of the field of view, but the vignetting
effects are severe and uncertain. A brief Chandra observation now
will let us assess the feasibility of a Cycle 25 proposal for a deeper
observation.

Sequence Number: 402454

Sequence Number: 402453

Title : Chandra observation of possible nuclear transient in NGC 7793
PI: Brightman
Abstract: We have recently reported the discovery of a nuclear transient in the
nearby galaxy NGC 7793 (3.8 Mpc), serendipitously detected by
Swift/XRT (https://www.astronomerstelegram.org/?read=15632). The X-ray
source was not detected with Swift only two weeks prior, however a
Chandra source with a flux 3 orders of magnitude lower than seen has
been reported at the position of the Swift/XRT source. While this
appears to be a nuclear transient, the luminosity of 3.8x10^39 erg/s
does not preclude a transient ULX. The source position, with a Swift
positional accuracy of 3 arcsec, could plausibly be outside the
nucleus. However, a much more precise position with Chandra could rule
out the nucleus, implying a ULX, or narrow the position down to the
nucleus implying a TDE is more likely.

Sequence Number: 704863

Title : Pinpointing the Super-Massive Black Hole Leo I*
PI: Pacucci
Abstract: The presence of an SMBH of ~3 million solar masses (Leo I*) was
recently suggested via dynamical measurements at the center of the
local dwarf spheroidal galaxy Leo I. Due to the lack of gas in Leo I,
the only channel available to feed the SMBH and, thus, produce an
electromagnetic signature is via mass loss from red giant branch (RGB)
stars.
XMM-Newton detected an X-ray source (4XMM J100825.8+121839) ~15'', or
~18 pc, away from the dynamical center of Leo I. This source has an
[0.5-4.5] keV flux of ~4 x 10^-15 erg/s/cm^2, in agreement with our
prediction for the flux of the source. The dynamical center of Leo I,
which is a good proxy for the plausible location of the SMBH in Leo I,
has an uncertainty of ~10'', which makes the identification of this
source with the electromagnetic signature of Leo I* even more
tantalizing.
We request an 80 ks ACIS-S observation to locate the position of the
X-ray source with a precision < 0.5'' as soon as it becomes observable
by Chandra (10-14-2022).

Sequence Number: 704871

Title : Localisation of new X-ray transient Swift J023017.0+283603
PI: Evans
Abstract: Swift J023017.0+283603 is an X-ray transient detected by Swift-XRT
(ATEL 15454). Originally it was thought to be a TDE due to positional
coincidence with galaxy at z~0.035, and its very soft, thermal
spectrum. This has now been ruled out by its temporal behaviour, which
shows episodes of high flux (L~2e42 erg/s) followed by periods of
non-detection with limits around 1e41 erg/s.

The outburst is only seen in X-rays, and the best X-ray position, from
Swift-XRT is consistent both with the nucleus of the putative host,
2MASX J02301709+2836050, and also with a two year-old supernova, SN
2020rht. Chandra is the only facility capable of giving a localisation
of this object accurate enough to unambigously confirm the association
with the nucleus, supernova, or neither, which is vital to determine
the nature of this enigmatic object.

Sequence Number: 100227

Title : Evaporation of a habitable-zone exoplanet with a water envelope
PI: Poppenhaeger
Abstract: We request a short (10ks) Chandra-HRC-S observation of a recently
discovered exoplanet which resides in the habitable zone around a
near-by M dwarf and has a density consistent with a thick water
envelope. An X-ray observation would allow us to measure the stellar
X-ray flux irradiating the planet, which is the driver of atmospheric
evaporation of exoplanets. Current upper limits for the host star are
only available from ROSAT and are uninformatively high (with ca. 5e27
erg/s). The anticipated measurement (allowing a detection down to Lx =
3e26 erg/s, practically guaranteeing a detection for an M dwarf) would
tell us whether this exoplanet is subject to a similar X-ray flux like
the small exoplanet GJ 436 b, which shows a huge atmospheric
evaporation tail. If so, this planet could be followed up meaningfully
at other wavelengths to test for the presence and density of its
evaporation plume and constrain habitability.

Sequence Number: 402452

Title : Localizing an unusual long-lived faint X-ray transient
PI: Maccarone
Abstract: Through the Swift Galactic Bulge Survey, we have discovered an X-ray
transient that has been on for over a year, but that has never gotten
particularly bright (0.2-0.6 cts/sec with Swift). The Swift positions
are inadequate for reliable identification of its optical counterpart.
It is likely a type of symbiotic X-ray binary activity not seen before
and there is a red giant within the error box. As symbiotic X-ray
binaries are an important stage in the evolution of LISA-band sources,
this is an important phenomenon to understand. We request a short
Chandra observation to localize the source.

Sequence Number: 704863

Sequence Number: 503440

Title : Confirmation of a magnetar driving an extremely long GRB
PI: Gompertz
Abstract: Ultra-long GRBs, with durations well in excess of a thousand seconds,
are believed to be driven by rapidly-rotating and highly magnetised
neutron stars known as magnetars. Evidence for this comes from the
unusually luminous SN 2011kl, associated with ULGRB 111209A, which
could not be explained with a plausible 56Ni model. Here, we request
observations of ULGRB 220706A, which shows evidence for a magnetar
engine in the GRB itself. It exhibits a late, long-lived energy
injection plateau that is consistent with dipole spin-down, and a
possible periodic signature of 3.5ms. The burst also shows a candidate
emission line during late flaring activity.

No optical counterpart has been identified, so the best localisation
comes from Swift-XRT, which is imprecise. Chandra observations can
improve the localisation so that an association with a host can be
made and a redshift obtained. They can also confirm that our
unprecendented long-lived plateau is not due to a contaminating
background source.

Sequence Number: 201554

Title : X-ray driven chemistry in the protoplanetary disk of DQ Tau
PI: Getman
Abstract: X-ray flares are expected to induce time-variable ion-molecular
chemistry in young protoplanetary disks. DQ Tau is a young, high
eccentricity binary that exhibits flux increases in
X-ray/optical/mm-band near periastron and offers a unique laboratory
for gas-phase ion disk chemistry. We won ALMA program to observe the
reaction of molecular line emission to ionizing radiation across one
binary orbit. Complementary to the approved NuSTAR/Swift observations
near periastron, we request Chandra snapshots away from periastron to
measure X-ray fluxes as inputs to a time-resolved physical-chemical
disk model. The model and ALMA data will provide unique estimates of
disk density distribution that have far-reaching implications for
understanding evolution of disks and formation of planets.

Sequence Number: 201553

Sequence Number: 201552

Sequence Number: 201551

Sequence Number: 201550

Sequence Number: 201549

Sequence Number: 201548

Sequence Number: 201547

Sequence Number: 201546

Sequence Number: 201545

Sequence Number: 201544

Sequence Number: 201543

Sequence Number: 503371

Title : A precise position for the likely very local GRB 220611A
PI: Levan
Abstract: GRB 220611A is a long duration GRB located 15 from an S0 galaxy at a
distance of only 220 Mpc (the third closest GRB in 18 years of Swift
operations). It has a very low probability of chance alignment (0.3%).
However, the host galaxy shows no sign of star formation, and the
offset is more in keeping with short GRBs formed from compact object
mergers than from long bursts formed from collapsars. Recent evidence
suggests that long bursts can be formed from mergers, and so this is a
plausible channel for GRB 220611A. The RA of the burst is such that it
cannot be viewed from the ground, and so we currently lack an accurate
position. However, Chandra observations can pinpoint the afterglow
within its host, revealing any star formation at the burst location,
or a more distant galaxy should the burst arise from a chance
alignment. Such a precise position can therefore greatly enhance (or
repudiate) the possibility that the burst is at 220 Mpc and inform the
collapsar/merger origin.

Sequence Number: 402361

Title : Disk winds in IGR J17091-3624 in the exotic variability state
PI: Wang
Abstract: IGRJ17091-3624 is a peculiar black hole binary (BHB) as it exhibits
exotic variability patterns that are highly structured, very similar
to GRS 1915+105. After the two major outbursts in 2011 and 2016,
IGRJ17091-3624 went into a new outburst in March 2022. With our NICER
and NuSTAR campaign, we observe Fe XXV and Fe XXVI absorption lines in
NICER spectra in the exotic variability state. These absorption lines
indicate the presence of disk winds, which are crucial to understand
the nature of the exotic variability of accretion flow thought to be
due to disk instability either because the black hole accretes at a
high mass accretion rate close to the Eddington limit, or disk
tearing. We request 1 Chandra/HETG observation of 30 ks to study the
disk winds in IGRJ17091-3624 in its current exotic variability state.
Joint observations with our approved NICER and NuSTAR GO program
(#5118) are highly favored.

Sequence Number: 402360

Title : Chandra high-resolution imaging of a new transient ultraluminous X-ray
source in M81
PI: Brightman
Abstract: We propose a Chandra DDT observation of a newly discovered X-ray
source in the nearby (3.7 Mpc) spiral galaxy M81. The source seems to
be a new ultraluminous X-ray source (ULX) that has recently appeared,
never before detected, despite numerous X-ray observations of the
galaxy. This source is one of a handful of transient ULXs we have
discovered recently while searching through Swift/XRT observations.
These new ULXs appear to lie among an older stellar population, where
models imply neutron star accretors are dominant. Unlike the previous
sources identified, M81 has ample HST coverage allowing a search for
an optical counterpart, and to age the stellar population of its
environment. There are also candidate optical transients from ZTF in
the Swift localization region. A 10-ks Chandra observation will
provide the accurate X-ray position to identify the counterpart.

Sequence Number: 402359

Title : Confirmation of a candidate nearby off-axis short GRB
PI: Gompertz
Abstract: GRB 220412B is an extremely short duration gamma-ray burst lasting
just 140ms. Prompt X-ray and optical follow-up revealed no
corresponding afteglow to deep limits at early times. However, our VLA
observations at 10 days after trigger reveal a bright (~380 uJy)
uncataloged radio source offset just a few arcseconds from the center
of the BAT localisation. These observations are consistent with an
`off-axis' GRB wherein the jet is not directly pointed towards Earth.
The afterglow is initially beamed away from the observer and is later
seen to rise as the relativistic Doppler beaming lessens. The radio
source is not coincident with any known galaxy nor optical emission in
archival images. We therefore request observations with Chandra to
explore its multi-wavelength properties and potentially confirm it as
the GRB afterglow in the local Universe.

Sequence Number: 201530

Title : A Chandra and ALMA View of the Origin and Impact of M-dwarf Flares
PI: Howard
Abstract: Recently, a large millimeter flare was detected from Proxima Cen.
Since little is known about millimeter flares, we have been awarded 40
hours of upcoming ALMA Cycle 8 observations to determine UV-millimeter
flare relationships using nearby M-dwarfs of various ages and activity
levels. We propose simultaneous ACIS HETG observations of the most
active target (Wolf 359) to constrain the high-energy spectral
properties of millimeter flares and their potential impact on planets.
We apply for DDT time as the ALMA scheduling will occur soon. Previous
observations of Proxima Cen by Chandra and ALMA show X-ray and
millimeter flares trace each other closely, and this proposed study
will help determine if this is a universal property of mid-M dwarfs
regardless of age, thereby creating a powerful new tool to determine
the high-energy environment of stars.

Sequence Number: 201529

Sequence Number: 201528

Sequence Number: 704610

Title : A Delayed Jet in a Tidal Disruption Event
PI: Cendes
Abstract: We request a 15 ksec DDT observation of the tidal disruption event
(TDE) AT2018hyz, which has begun rapidly brightening in the radio/mm
~2.2 years post-disruption despite no prior radio detections. Our
radio/mm data are potentially indicative of a relativistic jet
launched with an unexpectedly long delay relative to the time of
disruption, making this the first TDE with evidence for a delayed jet
(and only the second relativistic jet overall). Because the
synchrotron cooling frequency lies above the radio/mm band, Chandra
observations are crucial to pinpoint its location in order to
determine if the outflow is in equipartition, and to accurately
determine its radius, velocity, and energy, as well as the ambient
density around the supermassive black hole. If the Chandra
observations confirm a delayed relativistic outflow, this would
indicate that TDE jets can be produced at low accretion rates rather
than in the early super-Eddington phase.

Sequence Number: 704603

Title : Probing the X-rays from an unprecedented SMBH Binary at the Last
Inspiraling Stage
PI: Jiang
Abstract: We have recently discovered the first likely SMBH merger event ever
discovered in human history. The final merger will happen within three
years, maybe as short as three months. High-quality X-ray spectra
might be one of the most powerful electromagnetic signal to study the
last inspiraling stage. Our requested XMM-Newton ToO observations on
Dec.31 and Jan.19 have unveiled ultra-high velocity (>0.1c) absorbers
with drastic change, that is natural in binary scenario but never been
seen in normal AGNs. Chandra turns out to be the only facility which
can further monitor the unprecedented target with high-quality spectra
in the next five months (from Feb. To June, visibility gap for
XMM-Newton). Hopefully Chandra will contribute significantly to
confirm the first SMBH binary merger event and explore high energy
physical process happening during the final stage of the binary
inspiral.

Sequence Number: 704603

Sequence Number: 402355

Title : An Intermediate Mass Black Hole Candidate at the Centre of 47 Tuc
PI: Paduano
Abstract: We are currently in the middle of a large radio observing campaign
(406 hr) with the Australia Telescope Compact Array (ATCA) which will
produce the deepest radio image of the globular cluster 47 Tucanae to
identify faintly accreting black holes. Preliminary results from our
ongoing campaign based on data acquired in April/July/October 2021
have identified a radio counterpart to a previously identified faint
X-ray source. Its location at the photometric centre of the cluster
implies this object could be an intermediate mass black hole (IMBH)
candidate. As 47 Tucanae has not been observed by Chandra since 2015,
we request a 20 ks observation quasi-simultaneous with the last
segment of our ATCA observations to rule out the possibility of
enhanced radio/X-ray activity from an XRB. This will allow us to
assess the presence of an accreting IMBH in a globular cluster based
on direct evidence for the first time.

Sequence Number: 503370

Title : Search for the X-ray counterpart to GLEAM-X J162759.5-523504.3
PI: Hurley-Walker
Abstract: During a Galactic Plane survey with the Murchison Widefield Array
(MWA), a peculiar periodic radio transient has been discovered
(Hurley-Walker et al. 2021, Nature in press; info under embargo) with
a periodicity of 1091.169(5) s, a very variable flux, going from
undetected to values as high as 20-50Jy during periods of radio
outburst, lasting a few months (two such periods were observed in
January and March 2018), with a 90% linear polarization, and a very
spiky and variable pulse profile. From a detailed timing analysis, a
dispersion measure of DM=57+/-1 pc cm^-3 was calculated (distance~1.3
kpc). We expect this to be a magnetar having witnessed a conspicuous
fall-back accretion at birth that slew down its spin period
substantially. A short Swift XRT observation of ~5ks could constrain
its X-ray luminosity to < 10^33 erg/s. If it is a magnetar the source
might have in quiescence, a luminosity of ~10^30 erg/s. Deeper X-ray
observations are needed to set meaningful constraints.

Sequence Number: 402357

Title : Tracking the X-ray Emission of the Remarkable SGRB 211106A
PI: Rouco Escorial
Abstract: The distribution of jet angles for short gamma-ray bursts (SGRBs) is
critical to constrain as it directly affects the true energy scale and
event rate, which is of particular interest in the midst of the new
LVK run for next year. Our current knowledge of the jet angle
distribution comes almost exclusively from X-ray observations at >1
day after the burst. Here, we propose for a Chandra DDT observation to
continue to monitor the afterglow of SGRB 211106A and constrain its
late-time collimation up to ~60 days post-trigger, either from the
detection of the X-ray afterglow, which places a lower limit on the
opening angle at >15 deg, or a non-detection of the afterglow,
indicating a jet break has occurred and constraining the jet break to
20-25 deg. We have broad-band afterglow observations, which will be
leveraged to provide the tightest constraints on the jet angle.

Sequence Number: 402357

Sequence Number: 402356

Title : The wide angle outflow of SGRB 210726A
PI: Schroeder
Abstract: The distribution of jet angles for short gamma-ray bursts (SGRBs) is
critical to constrain as it directly affects the true energy scale and
event rate. The event rate is of particular interest in the
gravitational wave era. Our current knowledge of the jet angle
distribution comes almost exclusively from X-ray observations at >1
day after the burst. Here, we propose for a Chandra TOO observation to
continue to monitor the afterglow of SGRB 210726A and constrain its
collimation, either from the detection of the X-ray afterglow, which
places a lower limit on the opening angle at >35 deg, or a
non-detection of the afterglow, indicating a jet break has occurred
and constraining the jet break to 13-35 deg. We have broad-band
afterglow observations, which will be leveraged to provide the
tightest constraints on the jet angle. This would be the first
detection of a cosmological SGRB afterglow at >50 days, complementing
the longest lasting detections of an SGRB radio afterglow.

Sequence Number: 402355

Sequence Number: 503370

Sequence Number: 503369

Title : Ejecta Collimation and True Energetics of GRB210905A at z=6.318
PI: MARGUTTI
Abstract: We propose deep Chandra observations of GRB210905A at z=6.318 to
solidly locate the afterglow jet break time, and hence constrain the
ejecta collimation and true energetic of a GRB belonging to the rare
class of z>6 burst

Sequence Number: 704586

Title : Was the TDE candidate eRASSt J0936 produced by a wandering SMBH?
PI: Malyali
Abstract: On 2021-05-13, eROSITA detected a new TDE candidate, characterised by
an ultra-soft (kT~70 eV) X-ray spectrum and associated with a recently
quiescent FRII galaxy at z=0.12 (eRASSt J0936; see ATel#14668).
Follow-up Swift observations since the eROSITA detection revealed a
declining X-ray flux, with no significant X-ray spectral change (i.e.
remains ultra-soft); the latest observed 0.2-2 keV flux was
(5+/-3)e-14 erg/s/cm2 on 2021-10-06.
The implied SMBH mass from the M-sigma relation for this galaxy is
log(Mbh/Msun)~8.8, which exceeds the Hills mass for tidal disruption
of a MS star by a non-spinning SMBH. Recent work suggests a
significant fraction of TDEs may be produced by wandering SMBHs that
lie off-nuclear in their host (Fig. 2 of Ricarte+ in arXiv
2107.02132)- this may explain why we see a TDE candidate in a galaxy
with log(Mbh/Msun)~8.8. We request a 30ks observation of J0936 with
HRC-I to constrain the location of J0936 to within ~1.1 kpc (0.5; 3
sig.) of the host's centre.

Sequence Number: 402354

Title : Determining the Mass of the IC 10 X-1 Black Hole with Coordinated
Multiwavelength Observations
PI: Binder
Abstract: We request a 30 ks DDT Chandra/ACIS-S observation of the black hole
(BH) + Wolf-Rayet (WR) binary IC 10 X-1 to complement approved
Hubble/COS FUV spectroscopy and Swift/XRT+UVOT monitoring between 9-22
Nov 2021. The Chandra observation will allow us to determine the
orbital phases at which the Hubble and Swift observations are obtained
to high precision, model the X-ray spectrum and radiation field in
which the FUV lines form, and constrain the period derivative Pdot of
the system.

Sequence Number: 503368

Title : VLA+Chandra Observations of Ic-BL Supernovae with ZTF High-Cadence
Light Curves
PI: Ho
Abstract: Broad-lined Ic supernovae (Ic-BL) are a subclass of stripped-envelope
core-collapse supernovae notable for their high energies, high
velocities, and association with long-duration gamma-ray bursts
(GRBs). After decades of follow-up efforts, it remains unknown why
most Ic-BL SNe lack a detected GRB. Nearby (z<0.065) Ic-BL SNe
associated with low-luminosity GRBs (LLGRBs) may represent the answer:
LLGRB-SNe have been argued to be jets viewed off-axis, jets choked
inside the stellar envelope or circumstellar material, or successful
jets that are less powerful than classical GRBs. Here we propose
observations of ZTF21acekmmm to test a novel approach, based on the
fact that nearby LLGRB-SNe exhibit an early (<1d) flash of optical
light that can be routinely resolved by high-cadence optical surveys
like the Zwicky Transient Facility.

Sequence Number: 402353

Title : HIGH RESOLUTION STUDIES OF EXO 2030+375 DURING THE PEAK AND DECLINE OF
ITS RARE GIANT OUTBURST
PI: Pradhan
Abstract: As of Sep 10, EXO 2030+375 is rising in BAT indicative of the onset of
giant erratic Type II outburst seen only twice in the source since
discovery. We take this rare opportunity to study high-res
characteristics of the source near outburst peak and during its
decline for 10 ks and 20 ks respectively. We will probe accretion
near Eddington luminosity and disk winds through the study of the
X-ray continuum, emission lines and high velocity outflows. Since the
luminosity at giant outbursts are also thought to be accompanied by
such high velocity out seen in a few Be X-ray binaries so far, we
expect to find the outflows in EXO 2030+375. We will also: look for
variability of fluorescence lines originating in accretion disk and
place constraints on the Alfven radius to provide a magnetic field
estimate of the neutron star in the system and investigate the
scattering halos by studying the differences between the source and
halo light curves.

Sequence Number: 503296

Title : A luminous kilonova or a faint supernova? The curious case of
GRB210704A
PI: Troja
Abstract: GRB210704A is a GRB of intermediate duration (T90~4 s) whose
progenitor remains uncertain. Its location in a nearby galaxy's
cluster as well as the lack of any on-going star formation support an
old progenitor system, such as a compact binary merger. However, its
duration and bright long-lived afterglow are more typical of a long
duration burst. Its hybrid properties may also point to an exotic
channel of formation, such as as the merger of a white dwarf/black
hole system. We request a Chandra observation to track the evolution
of its non-thermal emission to late times, when the source has faded
below the Swift XRT detection threshold. These observations are
critical to characterize the standard afterglow, identify any excess
emission, and ultimately understand the nature of the shallow
optical/nIR decay which is a direct clue to the GRB progenitor
system.

Sequence Number: 300502

Title : Dissecting the Supersoft Source Phase of the Magnetic Nova V1674 Her
(Nova Her 2021)
PI: Drake
Abstract: V1674 Her (Nova Her 2021) is the first bright nova supersoft source
that has been identified with a magnetic white dwarf progenitor. An
8.357 minute period was found in ZTF data taken between 2018 and 2021
that is most likely caused by the spin period of the WD, strongly
indicating an intermediate polar. The presence of strong neon emission
lines in spectra from 2021 June 30 also demonstrate that V1674 Her is
a member of the class of neon novae. It has become a very bright
supersoft X-ray source with a Swift XRT count rate of 10 count/s. A
Chandra LETG+HRC-S spectrum should be uncomplicated by accretion and
can be phase-folded with the known period. It will provide a powerful
test of whether or not nuclear burning is insensitive to the local
magnetic field, and reveal velocity signatures of radiatively-driven
outflow collimation. V1674 Her is the first bright SSS to be so
characterized prior to outburst.

Sequence Number: 300501

Title : Searching for pulsations in a magnetic CV's nova
PI: Maccarone
Abstract: The bright, fast nova TCP J18573095+1653396 has shown an 8.4 minute
period in ZTF data that were taken before the nova explosion. This
period makes sense as a magnetized white dwarf's spin period. This
creates the potential for determining if the supersoft phases of these
systems show the spin oscillations of the white dwarfs. The period is
an awkward one for being reliably detected by satellites with
low-Earth orbits, so a short Chandra observation is requested.

Sequence Number: 402298

Title : HETG Spectroscopy of the Black Hole 4U 1543-475
PI: Miller
Abstract: 4U 1543-475 is a recurrent black hole X-ray binary. It is one of the
few sources with a dynamically confirmed mass, and measured distance
(M = 9.4 +/- 2.0 Msun, distance = 7.5 +/- 1.0 kpc; Park et al. 2004).
This means that it is a rare case wherein black hole spin can be
measured using continuum fitting. The source has risen very quickly
from the detection of renewed activity only (up to 2.5-3 Crab in just
2-3 days, see ATEL 14701). It is now in the soft state, which is the
one wherein spin can be measured as other contributions to the
continuum are minimal. In this state, disk winds and UFOs can also be
detected using the HETGS. With the ACIS-S array in CC mode, Chandra
is uniquely able to observe a source this bright without distortions.

Sequence Number: 503295

Title : Chandra Observation of AT2020mrf: the Most X-ray Luminous AT2018cow
Analog
PI: Yao
Abstract: The past several years has shown that the landscape of massive-star
death is unexpectedly rich and diverse. The (heterogeneous) class of
``fast blue optical transients'' (FBOT) has now established that a
large fraction of massive stars undergo significant mass losses, and
in some cases these losses serve as omens of their deaths
(supernovae). The discovery of AT2018cow (z=0.0141) established a
genuinely new type of cosmic explosion. AT2018cow was not only an FBOT
but was marked by intense X-ray emission and variability which
requires a powerful long-lived engine. Its high radio luminosity and
late millimeter peak implied dense circum-stellar medium (CSM).
Following the discovery of AT2018cow two events, ZTF18abvkwla
(z=0.271), CSS161010 (z=0.034; archival analysis), and AT2020xnd
(z=0.244) were identified. A fundamental open question is the nature
of the central engine. The X-ray band is essential since it probes
materials closest to the central power source.

Sequence Number: 402296

Title : Probing the disc-wind-jet connection in black hole transients
PI: Diaz Trigo
Abstract: We request three 50 ks observations of the candidate black hole
low-mass X-ray binary MAXI J1803-298 during the hard-to-soft state
transition with Chandra/HETGS to investigate the presence of narrow
X-ray absorption/emission features in the spectra, which are a
signature of a disc wind, and their relation to the accreting regime.
Such features, identified with ions like Fe XXV and Fe XXVI give us
information about the mass outflow rate and the launching mechanism of
the wind. With coordinated radio observations we will probe the
relationship between jet power and wind properties and how the radio
flux density correlates with the X-ray flux in different accretion
regimes.

Sequence Number: 704293

Title : Chandra grating observations of a newly launched outflow from a
supermassive black hole during an outburst
PI: Pasham
Abstract: We are requesting for a 50ks Chandra/LETG exposure of the nuclear
transient AT2019avd following NICER discovery of an outflow. LETG data
would provide a detailed view of this newly launched outflow as the
supermassive black hole (SMBH) is currently transitioning from an
X-ray soft to an X-ray hard state. This is analogous to a high/soft to
low/hard state transition in X-ray binaries which is often accompanied
by outflows. NICER has been monitoring AT2019avd at an unprecedented
cadence of once to several visits per day since its first public X-ray
detection on 19 Sept 2020. The proposed Chandra data will be part of
the legacy dataset to study accretion state transitions in SMBHs and
will guide future observations of SMBH outbursts with the upcoming
XRISM mission. This state transition and outflow could not have been
predicted at the time Chandra GO proposals were due and this
opportunity will not be available until the next GO cycle as the
source is already declining in flux.

Sequence Number: 704293

Sequence Number: 402297

Title : The disk/jet connection of a black hole in quiescence
PI: Carotenuto
Abstract: Black hole X-ray binaries display a correlation between the radio
luminosity originating from the relativistic jets, and the X-ray
luminosity, linked to the inner accretion flow. Some outlier (hybrid)
sources display a correlation that varies with the accretion rate, and
their behaviour in quiescence is still unknown. The path of a source
on the radio/X-ray diagram can be used to test models of accretion
flows and jets emission mechanisms. The new BH MAXI J1348-630 has been
densely monitored during its 2019/2020 outburst and is, so far, the
hybrid source with the best coverage, but its quiescence level has not
been constrained yet. We propose a single DDT Chandra observation (30
ks), that will be coupled to a deep radio observation (24h with ATCA)
in July 2021 (already scheduled), which will allow us to detect an
hybrid source in quiescence and therefore constrain its full path
along the radio/X-ray diagram from outburst down to quiescence.

Sequence Number: 503295

Sequence Number: 503294

Title : Search for jet afterglow from a magnetar-powered X-ray transient
PI: Lin
Abstract: Chandra just serendipitously detected a fast X-ray transient on 2021
April 23. It has a special X-ray light curve of a fast rise to a
plateau lasting a few thousand seconds, followed by a steep decay,
very similar to CDF-S XT2, which was recently shown to be powered by a
magnetar formed in a binary neutron star (BNS) merger. Such a unique
signal, if confirmed, can be synthesized with gravitational wave to
probe BNS mergers and dense
matter. We request a 60 ks Chandra observation to be carried out in
one month to search for a delayed off-axis jet afterglow in order to
confirm its BNS merger nature.

Sequence Number: 402296

Sequence Number: 402295

Sequence Number: 402294

Sequence Number: 704292

Title : A look at NGC 4151 at an exceptional flux and hardness
PI: Miller
Abstract: As of April 22, NGC 4151 is the brightest that it has been in the
Swift BAT, and today's Swift XRT snapshot records a flux 20% higher
than prior high-flux states (that are typically associated with low
BAT fluxes). Further proof of a rare accretion state and accretion
flow can be gleaned from ZTF monitoring, which finds NGC 4151 at its
brightest point for the entire monitoring period. The sensitivity and
resolution of the HETG is ideal for studying the narrow Fe K line and
disk winds. In prior published results, we showed that this line is
likely asymmetric and may arise at radii smaller than the BLR, rather
than within the BLR or torus. Whereas the equivalent width of this
line is 180 eV in prior Chandra spectra of hard states, and <100 eV in
soft states, the latest XRT snapshot suggests an equivalent width of
500-700 eV. This presents a remarkable opportunity to study the
accretion flow in this key source. We request a 50 ks obs.,
commensurate with the longest observing window.

Sequence Number: 503293

Title : Unraveling the nature of the persistent radio source associated to
FRB201124A with Chandra
PI: Piro
Abstract: FRB201124A is the second repeating fast radio burst (FRB) in which a
persistent radio source (PRS) has been very recently detected. Due to
its its closer distance (z=0.098), observations of the field of
FRB201124A can provide further insights into the nature of PRSs
associated to FRBs. Recently, multiple FRBs were detected from
FRB201124A by ASKAP, uGMRT, and the VLA. Following this, we performed
observations with the VLA and Swift/XRT. In our VLA observation, we
detect a PRS consistent with the locations reported for the VLA FRBs,
uGMRT FRBs, and uGMRT persistent radio source. Using the spectral
energy distribution for the persistent source, we determine that the
unique sensitivity of Chandra will allow us to detect the source with
high significance. This will yield a subarcsec location accuracy and a
solid association with the PRS allowing us to determine the offset of
the PRS from its galaxy and the FRB. We hereby request a 30 ks DDT
observation with Chandra to accomplish this goal.

Sequence Number: 503292

Title : CHANDRA DDT observation of the nuclear transient -
ASASSN-20hx/AT2020ohl
PI: Mandal
Abstract: ASASSN-20hx/AT2020ohl was discovered in the nearby (z=0.0167) X-ray
and radio faint, galaxy NGC 6297. The post-discovery Swift follow-up
for more than 200 days showed that the object is bright in X-ray, NUV,
with persistently bluish nature consistent with canonical TDEs,
although unlike TDEs this object has not shown any line formation in
the optical spectrum over this long duration. To identify the nature
of the source we have triggered Jansky Very Large Array (JVLA) in
X-Band (proposal ID: VLA/20B-427), and detected the high-frequency
radio counterpart at the center of the galaxy as well as another radio
source very near (~1.5'') to the center. We are now motivated to
observe the field using CHANDRA/HRC-I to find out the X-ray
association with one of these two radio-knots. Noteworthy, this field
was never imaged from CHANDRA. Here we propose for one epoch
CHANDRA/HRC-I ToO observation of the field of AT2020ohl in the highest
spatial resolution.

Sequence Number: 402293

Title : An accurate position of a new nearby ULX in NGC 4945
PI: Brightman
Abstract: On February 8th, we discovered a new ULX in the galaxy NGC 4945
(http://www.astronomerstelegram.org/?read=14380). The new ULX was
detected serendipitously in a Swift/XRT observation of the galaxy, and
no X-ray source has been reported at or near this position before
despite numerous previous Swift, Chandra, XMM-Newton, and NuSTAR
observations. We have continued to follow the source with Swift,
finding that the source continues to be active, and here we request to
follow up with a Chandra observation. The Chandra data will provide an
accurate position of the source, which will in turn allow a search for
a potential optical counterpart. We already have a candidate
counterpart in the 2.7" Swift positional error circle, but Chandra is
needed to confirm this. We request a 10-ks exposure, which is required
to detect enough X-ray sources in the field of view to carry out the
astrometric correction.

Sequence Number: 503291

Title : A Highly-Polarized, Highly-Variable Radio Source Near the Galactic
Center: A New Magnetar or Transitional MSP?
PI: Kaplan
Abstract: A highly variable radio source was discovered by ASKAP about 4 degrees
from the Galactic Center (GC) at a latitude of -0.03. Bright,
polarized emission was recently detected with MeerKAT but with large
flux variations on timescales of hours/days. The location of the
source within the plane and close to the GC along with the radio
variability/polarization point to a pulsar nature for this intriguing
object. The source might be a radio-loud magnetar or a transitional
millisecond pulsar (tMSP). In the case of a magnetar the radio
emission is always observed in connection with an X-ray outburst. If
this source is a tMSP it should be now in its ?intermediate? or
?pulsar'' state, again with predicted X-ray emission. In either
interpretation the source would be very interesting: either would be a
rare source, and both would allow important constraints on the pulsar
progenitors and population in that region.

Sequence Number: 503290

Title : Afterglow identification for short GRB 190610A
PI: Tohuvavohu
Abstract: GRB 190610A is a short hard burst discovered and localized by
Swift/BAT. The BAT localization is consistent with a nearby galaxy at
~165 Mpc. XRT follow-up observations yielded an afterglow candidate,
below existing upper limits. Due to the source's faintness a
determination of fading and the confident afterglow identification to
distinguish this from a possible contaminating background source
cannot be made with XRT. We request a late-time Chandra observation of
this XRT afterglow candidate, to help determine whether this burst is
a member of an extremely rare class of local, nearly on-axis, neutron
star mergers within the GW detector horizon.

Sequence Number: 704287

Title : Resolving the Flaring Site of PKS 1127-145 jet
PI: Siemiginowska
Abstract: On December 11, 2020 the Fermi-LAT Collaboration reported a strong
gamma-ray flare associated with the flat spectrum radio loud quasar
PKS 1127-145 at redshift z=1.184. This is the first strong gamma-ray
flaring activity observed from this source in the Fermi era with the
highest gamma-ray flux ever detected in this quasar, a factor of 50
higher than the average flux estimated in the 4FGL catalogue. This is
the first opportunity for Chandra to observe this quasar in an active
state. The Chandra observation will provide the required arcsec
resolution to confirm that the gamma-ray flare is associated with this
quasar and to locate the site of the flare.

Sequence Number: 503289

Title : GRB201214B: an off-axis burst in the nearby universe?
PI: Troja
Abstract: GRB201214B is a weak gamma-ray burst discovered by Fermi GBM and
localized by Swift BAT close to a nearby galaxy at D~280 Mpc. XRT
follow-up observations do not identify any counterpart within the BAT
error region, showing that this event is not associated with a bright
X-ray afterglow. Its weak gamma-ray signal, lack of early X-ray
emission and possible association with a nearby galaxy are reminiscent
of GRB150101B and GW170817, two off-axis afterglows detected by
Chandra. If GRB201214B is a similar explosion seen off-axis, its
afterglow would slowly rise and peak several days/weeks after the GRB.
We therefore request a pair of Chandra observations to search for the
onset of a delayed X-ray afterglow, and test whether this GRB heralds
a rare neutron star merger in the nearby universe.

Sequence Number: 503288

Sequence Number: 704286

Title : The recurring rebrightening of ESO253-G003
PI: Payne
Abstract: We discovered highly atypical flares within the AGN ESO253-G003 that
are periodic with a non-zero negative period derivative (Payne et al.
2020). These outburst events have occurred predictably for the last
six years. Numerous rebrightening events are highly unusual for an
AGN, which normally vary at a low-level following a damped random walk
model. The precise origin of these flares remains unknown but they
could be caused by a repeating partial tidal disruption event (TDE).
Studying this object will provide new and distinctive insights into
the mechanisms driving this transient and the broader inner workings
of AGN variability.

Sequence Number: 704285

Sequence Number: 100204

Title : On the shoulders of Gas Giants: Observing Saturn's X-rays with a
varying external driver
PI: Weigt
Abstract: In November 2020, the planets Jupiter and Saturn will be in unique
alignment: Saturn will be immersed in Jupiter's magnetotail. This only
occurs once in every 19 years and is unique to the gas giants. Voyager
2 ~40 years ago found the environment at Saturn during this time was a
variable parameter space and found the (magneto-)tail of Jupiter to
flap, without any coincident remote sensing or X-ray data. This caused
Saturn to be alternately every 2-3 days immersed in the rarefied tail
and then denser solar wind. These changes are likely to produce shocks
as the magnetosphere compresses and expands in response to changing
pressure and dynamics, brightening the aurora. However, there are
still many unknowns about how Saturn's auroral/disk emissions will
respond to no solar wind drivers.

Therefore, we propose to observe Saturn?s X-rays in this unique
unknown parameter space for the first time. The data provided will aid
the ongoing multiwavelength campaign, exploring Saturn's response.

Sequence Number: 100204

Sequence Number: 503287

Title : CHANDRA OBSERVATIONS OF A NEW SGR 1830-0645
PI: Kouveliotou
Abstract: Swift/BAT has discovered a magnetar-like soft (<50 keV) X-ray burst
(duration <0.1s) potentially from as new magnetar source, SGR
1830-0645 (GCN 28594). We would like to request a 10ks DDT observation
of this new source with HRC to determine an accurate position and
timing of its persistent emission. We intend, thereafter, to follow up
the source with XMM-Newton, and further determine its spectral and
timing properties. The magnetar population in our Galaxy is very small
(~30 sources) - this discovery will significantly, therefore,
increase this population and needs to be well studied. Further, the
source resides in a very dense area of the Galactic Plane (which
already hosts several magnetars) and HRC is the only instrument that
can locate it with great accuracy, so that we can have radio and
optical followup observations.

Sequence Number: 704283

Title : Resolving RXJ1756 with Chandra: A Recoiling Black Hole Candidate or
Possible Triple AGN
PI: Koss
Abstract: The coalescence of binary supermassive black holes in galaxy mergers
is thought to constitute the strongest source of gravitational waves.
Theory suggests these waves carry momentum causing the merged SMBH to
experience a velocity recoil or kick that displaces or may even eject
it from the center of its host galaxy. Despite their importance, only
a few spatially or kinematically offset recoiling BH candidates are
known, and none has been confirmed with extensive multiwavelength
observing. We request DDT time to follow-up a very recent 2020 Aug 2
HST, XMM-Newton, and NuSTAR
observations of an extremely puzzling source RXJ1756.4+5235, a
recoiling supermassive black hole candidate or possible triple AGN.

Sequence Number: 704254

Title : A dramatic change in an agn
PI: Miller
Abstract: A full science justification has been sent to the director in a
separate email.

Sequence Number: 704254

Title : A dramatic change in an agn
PI: Miller
Abstract: A full science justification has been sent to the director in a
separate email.

Sequence Number: 704254

Title : A dramatic change in an agn
PI: Miller
Abstract: A full science justification has been sent to the director in a
separate email.

Sequence Number: 704254

Title : A dramatic change in an agn
PI: Miller
Abstract: A full science justification has been sent to the director in a
separate email.

Sequence Number: 402282

Title : Chandra observation of the mysterious X-ray transient AT2019wey/SRG
PI: Kulkarni
Abstract: AT2019wey/SRG though discovered in December 2019 only rose to
prominence with the discovery of strong X-ray emission by the
Spectrum-Roentgen-Gamma (SRG) mission in March, 2020. The source was
not present in any historical optical sky surveys nor Rosat All Sky
survey, though it was detected at 17.5 mag and few mCrab just from
this year. The unusual nature of this Galactic source (various H and
He lines at z=0) led to generous allocation of Swift, NICER, and
NuSTAR monitoring time. The detection of relativistic reflection from
NuSTAR and the detection of radio emission from VLA, taken together,
suggest that the source is likely an accreting stellar black hole.
The long 'on state' is unprecedented for a low mass accreting black
hole binary.

We propose a Chandra HETG exploratory observation to detect possible
narrow line iron components and also spectrally resolve the low
energy (<1 keV) hump. These may provide new insights into the nature
of this mysterious transient.

Sequence Number: 704251

Title : Follow up a special hard tidal disruption event
PI: Lin
Abstract: We just discover a remarkable UV/X-ray outburst from Swift in our
archival data search. Because it is positionally coincident with the
nucleus of a nearby inactive galaxy at z=0.026, it is a strong tidal
disruption event (TDE) candidate. It is remarkable in three aspects:
(1) a well covered UV/X-ray light curve constraining the outburst
start time to within two weeks; (2) hard X-ray spectra (powerlaw
photon index 1.8-2.5) seen in only a few TDEs; (3) a surprising fast
rebrightening (by one order of magnitude and last for one month) in
X-rays but not in the UV during the overall decay. We now request a
Chandra observation to confirm the nuclear origin of the event, to
confirm the hardening of the X-ray spectra, as part of our long-term
campaign, to constrain the long-tern evolution of the X-ray emission.

Sequence Number: 503278

Title : Chandra observations of PSR J1846-0258 in outburst
PI: Blumer
Abstract: PSR J1846-0258 (J1846), powering a bright and compact pulsar wind
nebula (PWN) in the young supernova remnant Kes 75, was the first
high-magnetic (B) field pulsar to display a magnetar-like behavior in
2006, blurring the distinction between rotation-powered pulsars and
magnetars. Chandra observations of J1846 performed 7 days past the
outburst activity revealed that the pulsar brightened (by a factor of
6 times) and its spectrum softened significantly such that it became
reminiscent of those observed from magnetars. Subsequent observations
in 2009 revealed that the pulsar had gone back to quiescence. J1846
has entered into a new state of activity on 1 Aug 2020, emitting a
short burst detected with Swift. We request a prompt follow up
observation with Chandra to study its magnetar-like behavior in
comparison with the 2006 bursts, and to search for any PWN variability
associated with the burst.

Sequence Number: 402198

Title : Investigating the vertical structure of the disc wind in Her X-1
PI: Kosec
Abstract: Hercules X-1 is a unique neutron star X-ray binary system showing a
periodically precessing warped accretion disc. At the same time, it
exhibits a varying accretion disc wind. The variations are likely
driven by the disc precession and correspond to our observations
sampling different lines of sight above the warped disc, thus allowing
us to study the vertical disc wind structure. Our coordinated
XMM-Newton, NuSTAR and INTEGRAL campaign will observe a large part of
a single precession cycle of Her X-1, finely sampling the wind
structure, accurately measuring its total mass outflow rate and
shedding light on its launching mechanism. A simultaneous Chandra HETG
observation would greatly complement this dataset. It could fill-in
one of the XMM orbital gaps, expanding our time-resolved wind
parameter study. Additionally, it would allow us to cross-check the
wind parameters derived from XMM data, and to perform a full chemical
abundance study of the disc wind.

Sequence Number: 402198

Sequence Number: 503207

Title : X-ray observations of a candidate Pulsar Wind Nebula
PI: MARGUTTI
Abstract: We propose to re-observe the energetic SN2012au with Chandra. SN2012au
showed evidence for a remarkable radio re brightening (accompanied by
a radio spectrum inversion at GHz frequencies). Here we ask for deep
X-ray observations of SN2012au to constrain the high-energy part of
the spectrum and constrain the physical parameters.

Sequence Number: 503207

Sequence Number: 503206

Title : X-ray Progenitor Constraints of the Subluminous Type Ia SN2020nlb
PI: Sand
Abstract: SN2020nlb is a newly discovered subluminous type Ia SN in the nearby
galaxy M85 (D~15 Mpc), found within two days of explosion. While it
is accepted that SNe Ia are the thermonuclear explosions of CO white
dwarfs, it is still unclear by what mechanisms the white dwarf gains
the necessary mass and how it then explodes. Deep X-ray observations
provide critical information on SN Ia progenitors as a probe of the
circumstellar material they left behind. SN2020nlb would represent
the first subluminous SN Ia with deep CSM limits in the X-ray, and may
lead to the first definitive detection!

Sequence Number: 503206

Sequence Number: 704049

Title : INVESTIGATION ON MRK 335 IN AN INTERMEDIATE STATE
PI: Boissay-Malaquin
Abstract: We propose a DDT observation of the highly variable Narrow-Line
Seyfert 1 Mrk 335 with Chandra/HETG (150 ks DDT + 90 ks GTO). Because
of a pending observation accepted for cycle 5, NuSTAR will join such
Chandra observation on a best effort basis. We also seek to obtain a
contemporaneous NICER DDT observation. We aim to characterize the warm
absorbers previously detected in XMM-Newton/RGS data. We aim to
observe Mrk 335 in the next 10-20 days, while it has an intermediate
flux, ideal state for the detection of the absorbers. Observing now
ensures that we will catch the adequate intermediate state (according
to the Swift monitoring), but also offers a unique view of an AGN when
it is turning on again, after being in a low flux state for the past 2
years. These observations will provide high-resolution spectra that
will allow us to deconvolve and constrain the primary continuum, the
multiple absorbers, the narrow and broad iron lines, the local and
distant reflections and the soft excess.

Sequence Number: 704049

Sequence Number: 704048

Title : Detecting the softening of emission in quiescence in a supermassive
black hole
PI: Wevers
Abstract: Tidal disruptions of stars by supermassive black holes (SMBHs) have
long been proposed as probes of accretion state transitions around
SMBHs. However, due to a combination of lack of accurate physical
models and dedicated X-ray (corona) and UV (disk) monitoring programs,
such events have not yet been identified. We have been tracking the
first such case over the last 600+ days using the X-ray and UV data
from Swift, NICER, and XMM-Newton (see Fig. 1 of science
justification). During this time the source underwent two state
transitions, the only known SMBH to undergo such extreme and rapid
accretion regime changes, and now it is approaching a quiescent state.
Here, we propose for a 50 ks Chandra exposure, an estimated factor of
10 deeper than a recent XMM observation, to test various (currently
unconstrained) models of accretion physics.

Sequence Number: 503205

Title : Unpicking the threads of a rare collapsar explosion
PI: Troja
Abstract: GRB190829A is a rare nearby (z=0.08) gamma-ray burst of long duration,
followed by a bright Type Ic supernova. Recently it was proposed that
events like GRB190829A could produce large amounts of heavy metals,
and be the dominant sources of galactic r-process enrichment . The
characteristic signature would be a long-lived infrared emission,
outshining the supernova light months after the explosion. The main
obstacle in identifying this novel emission component is the bright
GRB afterglow. Continued X-ray monitoring of this GRB would
characterize its non-thermal emission, and allow us to disentangle the
afterglow contribution from any possible red excess. Only Chandra can
resolve the GRB counterpart from nearby contaminating sources.

Sequence Number: 402197

Title : Get to the Chopper!!! - Testing the Propeller Nature of the Off-States
in the ULX Pulsar NGC7793 P13
PI: Walton
Abstract: NGC7793 P13, one of the few ULXs known to be powered by a neutron
star, has recently entered an 'off-state' (i.e its flux is >10x below
its 'normal' ULX level). These may be related to the propeller effect,
and may offer an opportunity to determine the B-field (still hotly
debated). Based on its previous off-state (0.3-10 keV flux of ~3-6e-14
erg/cm^2/s), simulations suggest that a deep observation with XMM
could still detect pulsations if they are present, allowing us to
probe the nature of these rare and potentially key events. In order to
determine whether this is feasible for the new off-state we need to
confirm the current flux of the source, but this is now below the
detection capabilities of Swift. We are therefore requesting a short
DDT observation with Chandra. In addition, the excellent spatial
resolution will allow us to test whether the emission is point-like or
extended, following the detection of extended emission in an off-state
seen from the ULX pulsar NGC5907 ULX1.

Sequence Number: 503204

Title : Light echoes from the magnetar, SGR J1935+2154
PI: Gogus
Abstract: SGR 1935+2154 is one of the most burst prolific transient magnetars:
It was discovered in 2014 with Swift-BAT after emitting short duration
magnetar-like bursts, and exhibited three activity episodes in 2016,
2017, 2019 and a fourth one, which started a day ago. More than 35
bursts were recorded from the source in the last 24 hours (ATel 13675:
Palmer et al. 2020, GCN 27657: Barthelmy et al., 2020), MAXI (GCN
27661: Sugawara, Y. et al., 2020) as well as Fermi (GCN 27659:
Fletcher, C. et al., 2020) and Calet GBM (GCN 27663: Ricciarini et al.
2020). Swift XRT has also collected data in PC mode for about 2 ks in
response to the Swift trigger (#968211). We clearly detect an X-ray
ring around the source in this short exposure. The emission around the
source is also quite extended, reaching to about 0.5'. We propose a 10
ks pointing with ACIS-I to explore the ring, search for other rings
and a possible wind nebula powered by the magnetar.

Sequence Number: 100193

Title : Grating spectroscopy of the unexpectedly bright comet C/2019 Y4 ATLAS
PI: Bodewits
Abstract: Our observations will also allow us to study the temporal development
of the X-ray emission from Comet ATLAS under its rapidly changing
conditions. ATLAS is an Oort cloud comet discovered in December 2019
(MPEC 2020-A112). Based on its current brightness and behavior, it is
expected to become a naked-eye object in May and possibly the
brightest comet seen in the last decade. This provides a unique
opportunity to observe the comet with the Chandra gratings to acquire
a high resolution X-ray spectrum that allows us to resolve the low
energy line emission (< 300eV; Snios et al. 2016), to test new
theories about how solar wind charge exchange emission lines ratios
are affected by the composition of the neutral gas around comets
(Mullen et al. 2017), and to investigate the curious lines in the 1 to
2 keV region (Ewing et al. 2013).

Sequence Number: 100193

Sequence Number: 503203

Title : Chandra observations of the newly discovered magnetar Swift
J1818.0-1607
PI: Blumer
Abstract: Magnetars are young neutron stars believed to be powered by their
super-strong magnetic fields and exhibiting a diverse set of
observational properties. They go through long periods of quiescence,
interrupted by bursting activity over the course of days to months
that are followed by spectral and temporal changes. Magnetar activity
has also been recently observed in other pulsar classes. In this
proposal, we request Chandra observations of Swift J1818.0-1607, a
magnetar candidate discovered by Swift on 12 March 2020 and having a
1.36-s periodicity discovered by follow-up NICER observations. The
main scientific goals here are to detect and localize the X-ray
source, constrain its imaging and spectral properties, and confirm the
magnetar nature by studying its spectrum in comparison to other
magnetars. If detected in this DDT, we will separately propose for
follow-up and more detailed X-ray studies of this source.

Sequence Number: 300469

Title : Proof of concept for the detection of non-burning symbiotic binaries
PI: Lucy
Abstract: Non-burning symbiotic binaries--powered by the accretion of a cool
giant onto a white dwarf (WD), without shell burning on the WD--are
extremely difficult to find, which is why less than 5% of known
symbiotic stars are non-burning. But the true population of
non-burning symbiotics is likely much larger, and may hold the key to
testing how the large disks of symbiotics drive jets and winds. In
this PhD thesis work, we developed a novel strategy for finding
non-burning symbiotics using uvg colors and minutes-timescale
variability in SkyMapper. In 2019 Sep-Oct, we obtained Swift followup
observations of our top two non-burning symbiotic candidates, IRAS
15175-4508 and Haro 1-10, showing a 2sig X-ray detection and 4sig UV
flickering, respectively. We request Chandra observations of IRAS
15175-4508 and Haro 1-10 to confirm the presence of their accretion
disks before their high states end, and to validate our method of
uncovering this hidden population of supernova progenitor candidates.

Sequence Number: 300468

Sequence Number: 503202

Title : A Candidate Low-luminosity Gamma-ray Burst Identified by an Early
Optical Flash
PI: Ho
Abstract: Low-luminosity gamma-ray bursts (LLGRBs) are a rare class of
explosions with a relativistic energy release 2-3 orders of magnitude
smaller than that from classical GRBs. Due to their lower luminosities
they are only discovered nearby (z<0.1), so despite being 100x more
common than classical GRBs only seven have ever been discovered and
their origins remain unknown.

All LLGRBs are accompanied by a Type Ic-BL supernova (SN). Two events
(GRB060218/SN2006aj, GRB100316D/SN2010bh) have Chandra observations
from 10 to 40 days post-explosion that reveal an excess of soft X-ray
emission that may arise from a long-lived central engine such as an
accreting black hole or a magnetar. Early optical observations of
SN2006aj revealed a fast (<2d) blue flash prior to the onset of the
SN.

SN2020bvc (z=0.025) is a Ic-BL with an early blue flash similar to
SN2006aj (Astronote #2020-37). We propose Chandra observations to test
whether there is relativistic ejecta and compare this event to other
LLGRBs.

Sequence Number: 503201

Sequence Number: 201344

Title : The Dimming of Betelgeuse
PI: Kashyap
Abstract: Betelgeuse (M2Iab) is a prime candidate for an impending supernova. It
has been exhibiting an unprecedented dimming (Guinan & Wasatonic, ATEL
13410), dropping in luminosity by ~25% since Sep 2019. Prima facie
this cannot be attributed to adiabatic upwelling of higher temperature
material which explains its usual variability (see Dolan et al. 2016,
ApJ 819, 7). The stellar radius has decreased by 9% in 5 months (cf.
free-fall timescale t_ff~0.6 yr), suggesting that it is undergoing
significant structural changes due to a switchover from He- to
C-burning. This presents an unprecedented opportunity to observe the
process and detect the presence of high-energy processes should they
exist. Any detection of X-rays will be of fundamental importance to
understand the phenomenon being exhibited by Betelgeuse. If
undetected, we will set stringent upper limits to the X-ray flux by
combining these data with prior Chandra Cal observations.

Sequence Number: 201343

Sequence Number: 503200

Title : The nearby TypeIc/Ic-BL SN2020oi in M100 (d~16 Mpc)
PI: Stroh
Abstract: SN2020oi is a young type Ic/Ic-BL SN in the very nearby galaxy M100
(16 Mpc). We request X-ray follow-up in coordination with follow-up
across the spectrum with the primary objective to constrain the shock
velocity and the density in the nearby environment of the explosion.

Sequence Number: 503199

Sequence Number: 503198

Title : Chandra Observation of SN 2019yvq
PI: Pooley
Abstract: In 15 ksec of merged Swift/XRT observations since Dec 29, there are
26.1 +/- 6.0 net counts (0.2-10 keV) in a 45" aperture centered on the
Type Ia SN 2019yvq in NGC 4441 (19 Mpc). In a previous Swift
observation of the field from 2012, using the same source and
background regions, 7.1 +/- 3.5 net counts are detected. The clear
detection of an X-ray source in the new data may be from the SN or
possibly from an unrelated source. Chandra's sensitivity and spatial
resolution are necessary to determine the origin of the X-rays.

Sequence Number: 704036

Title : Follow-up of a Weak-Line Quasar with Extreme X-ray Variability
PI: Ni
Abstract: We request an observation of SDSS J1539+3954, a weak-line quasar (WLQ)
that exhibited extreme X-ray variability, to monitor its potential
change in X-ray flux. In Sept 2019, we unexpectedly discovered that
the X-ray flux of SDSS J1539+3954 had increased by a factor of > 20.
Before this rise, it appeared X-ray weak compared with the expectation
from its UV flux; after the rise, the ratio of its X-ray flux and UV
flux is consistent with the majority of the AGN population. In the
context of the thick inner accretion-disk model we proposed for WLQs,
the extreme X-ray variability could arise due to a slight change in
the thickness of the disk that moved across our line of sight. When
our line of sight intercepts the disk, we observe an X-ray weak state;
when it misses the disk, we observe an X-ray normal state. Monitoring
the potential X-ray state transition before the next Chandra CfP will
greatly help to constrain the timescale of such transitions, thus
probing the accretion-disk physics.

Sequence Number: 402196

Title : Intrabinary shock emission of the black widow candidate 4FGL
J0336.0+7502
PI: Li
Abstract: Many millisecond pulsars are in binary and some special ones are in
compact orbits, whose the periods are less than 1d. Depending on the
companion type, these MSPs are named black widow or redback. The
binary members in a black widow/redback are just separated by a few
solar radii. Under this extreme condition, pulsar intrabinary shock
(IBS), where the stellar/pulsar winds severely collides, is formed.
One side of the tidally-locked companion is heated by IBS that results
in orbital modulation in optical. The X-ray emission will also be
modulated by Doppler boosting. 4FGL J0336.0+7502 is a strong black
widow candidate, which was recently identified by our MSP hunting
campaign. Not only showing gamma-ray properties comparable to other
black widows, an optical counterpart that exhibits 3.72-h modulation
was also found. An X-ray counterpart is detected by Swift/XRT in 2012,
but just marginally. We propose a 15ks (~1 orbit) Chandra observation
to confirm the detection and study the IBS.

Sequence Number: 300467

Title : UNEXPECTED EARLY PERIASTRON PASSAGE AND ECLIPSE IN THE SYMBIOTIC
SYSTEM R AQR
PI: Karovska
Abstract: We propose a 50ks ACIS-S DDT observation of the interacting symbiotic
binary (where a WD accretes from the powerful wind of an evolved
giant), RAqr. The white dwarf accretor is making an unexpected early
approach to the mass donor Mira star. The enhanced activity in the
system has resulted in a powerful outburst and mass ejection, leading
to dust formation eclipsing the donor star, as evidenced by the recent
dramatic dimming of the optical light of RAqr. Symbiotic systems are
of great importance because they are likely progenitors of a fraction
of asymmetric Planetary Nebulae (PN), and of cosmological distance
indicator SN Ia. Understanding the characteristics of the accretion
onto the WD, and of the surrounding environment, especially during
powerful mass-loss events and outbursts around periastron, are crucial
steps to determine the precursor conditions for formation of PN and SN
Ia. ToO observing time has been granted recently on JVLA , HST, and
Swift to study this rare event.

Sequence Number: 704032

Title : X-ray jet at very high redshift
PI: moretti
Abstract: Powerful radio-loud QSOs emit relativistic jets of plasma. At high
redshift, their X-ray emission is thought to be partially due to the
interaction of the plasma with the CMB photons. Since CMB photon
density strongly evolves with redshift, radio-loud QSO X-ray
luminosity is expected to quickly increase in the early Universe. We
propose to observe PSO0309+47, the most luminous X-ray and radio QSO
recently discovered at z>6.0. Its redshift (z=6.1) and the QSO nature
has been confirmed by optical LBT spectrum in October 2019. A short
Swift-XRT observation, in November 2019, allowed us to roughly
estimate its X-ray spectral properties. Interestingly, the position of
the X-ray counterpart is (marginally) inconsistent with the optical
one. This could be interpreted as the signature of a jet interacting
with the CMB photons. A Chandra 25Ks observation, with 50 source
photons expected, would be able to confirm the positional offset and
to assess the extension of the source.

Sequence Number: 402195

Title : An accurate position of a new ULX in NGC 4045
PI: Brightman
Abstract: We recently detected a new X-ray source with Swift/XRT that appears to
be associated with the galaxy NGC 4045 (D=32 Mpc). The source was
first detected by Swift on 2019-12-04 and the latest detection was on
2019-12-06 with a count rate of 1.4E-02+/-3.3E-03 ct/s. The spectrum
can be described by a powerlaw with Gamma=1.1+/-0.7. The 0.3--10 keV
flux is 6.8E-13 ergs/cm2/s, which at a distance of 32 Mpc corresponds
to a luminosity of 6.3E+40 erg/s. The source is likely a new ULX. No
previous X-ray source has been catalogued within several armin of this
source. Observations with Swift several months prior yielded only
upper limits below the current count rate. We request a 10-ks Chandra
observation in order to obtain an accurate position that will
potentially enable the identification of an optical/NIR counterpart.
An OIR counterpart could yield information about the donor star of the
ULX. The 90% positional uncertainty from Swift is only 5.1" and would
yield several counterpart candidates.

Sequence Number: 100192

Title : Chandra Observations of the Interstellar Comet C/2019 Q4 Borisov
PI: Snios
Abstract: Comet 2019/Q4 Borisov is only the second-known interstellar object
detected within the Solar System, and the first to be discovered prior
to reaching its perihelion. This presents a unique opportunity to
extensively observe this exotic comet during its closest approach to
Earth prior to its exit from the Solar System. X-ray observations of
C/2019 Q4 may be used to measure dust and gas outflow rates from the
source, neutral particle interactions with Solar Wind, and variations
in outflow rates and morphology. These properties may also be compared
against Solar System comets/asteroids to probe for differences, if
any, with the exosolar object. We therefore propose to observe C/2019
Q4 with Chandra HRC during its perihelion on 27-Dec-2019 to quantify
the afore-mentioned physical properties of this interstellar comet.

Sequence Number: 100192

Sequence Number: 503197

Title : Simultaneous X-ray and Radio Observations of the Second Localized
Repeating Fast Radio Burst
PI: Scholz
Abstract: We have localized the CHIME/FRB-discovered repeating FRB
180916.J0158+65 to milliarcsecond precision using the European VLBI
Network and identified its host and redshift using Gemini North
observations. This is the second sub-arcsecond localization of a
repeating FRB. The redshift of the host galaxy implies a luminosity
distance at least six times closer than the only other localized
repeater, FRB 121102. Therefore, FRB 180916 can be used to probe much
deeper for X-ray emission from repeating FRBs. We propose to perform
simultaneous observations using Chandra and the 100-m Effelsberg radio
telescope to probe for X-ray emission at the times of radio bursts
from FRB 180916. See attached 1 page science justification for more
information.

Sequence Number: 503197

Sequence Number: 100192

Sequence Number: 704028

Title : Gravitational millilensing as a tool for studying the
microarcsec-scale structure in PKS1413+135
PI: Liodakis
Abstract: We have recently identified a new type of symmetric achromatic
variability (SAV) in light curves of AGN, which we suggest is due to
gravitational lensing. This allows us to probe lenses in the mass
range of 1e3-1e6 solar masses, which have been challenging to detect.
We propose observations of PKS1413+135, which has previously shown 5
SAVs in its radio light curve over the past 27 yrs and now shows
indications that a new event has recently started. Based on previous
events we expect it to continue until 07/2020. This is the first event
ever to be identified while in progress. We expect the X-rays to
follow the same achromatic trend seen in radio, observations of which
are underway. We request 17-4ks-pointings separated by 2 weeks that
will allow us to monitor the X-ray flux evolution during the event and
confirm its achromatic nature. Depending on the outcome, we will have
the unique opportunity to study grav. millilensing, plasma lensing or
intrinsic variability in relativistic jets.

Sequence Number: 704028

Sequence Number: 100191

Title : Exoplanet evaporation in the only known young 4-planet system
PI: Poppenhaeger
Abstract: Exoplanets lose their atmospheres through evaporation driven by
stellar X-ray emission. This leads to a gap observed in exoplanetary
radii; but the physics of evaporation is not well understood. A few
days ago, a new exoplanet system was discovered with 4 low-density and
hence easily evaporable exoplanets and a very young (25 Myr) host star
called V1298 Tau. This is the age at which the bulk of evaporation
should happen, and we can extract key insights on the evaporation
strength from this system if the X-ray luminosity of the host star is
known. ROSAT shows there is a source with a count rate of 0.15 cps
near the position of the star (Lx=2e30 erg/s). But there are 2 other
young stars in the ROSAT PSF (the smallest separation being 25
arcsec), so it is unclear if or how much of the flux stems from the
exoplanet host star. We ask for 1 ks of Chandra time with ACIS-S. This
will yield 70 counts in total, and we will easily determine how much
flux stems from the exoplanet host star.

Sequence Number: 402194

Title : GRS 1915+105 as a Changing-Look Microquasar
PI: Miller
Abstract: GRS 1915+105 is currently in a low flux state, with a flux of about 1
E-10 erg/cm^2/s. This is two orders of magnitude lower than the flux
for which it is famous. Via Swift monitoring, we know that the flux is
diminished partly through internal obscuration. At times, the source
now appears to be Compton-thick. GRS 1915+105 has always been a
Rosetta Stone source that has helped us to better understand quasars.
Now, it appears to be a highly obscured Seyfert-2 or Compton-thick
AGN. Swift spectra give us broad ideas about what might be happening,
but our simulations suggest that 30 ks Chandra/HETGS spectra can
reveal far more, including Doppler broadening of the flux that is
reflected by the obscuring material, and highly ionized outflows. It
may be the case that the obscuring material is actually an extreme
outflow, and that the source is losing more mass than it accretes. An
email has been sent to the director with a plot from one simulation.

Sequence Number: 402193

Sequence Number: 503196

Title : Chasing high energy emission from neutron star black holes merger
PI: Jaodand
Abstract: GW170817 opened up a new, interesting question in astronomy- what
would a neutron star black hole (NSBH) merger look like. In case of
such merger below a certain mass threshold where the NS is tidally
disrupted beyond an innermost stable circular orbit we expect to see a
bright red kilonova accompanied by a high mass tidal ejecta up to 0.1
M_Sun. Very recently, on August 14, LIGO/Virgo observatories jointly
detected a very promising NS-BH event (LIGO/Virgo S190814bv).
Detection of rising radio counterpart with ASKAP makes it first NS-BH
merger with a multi-wavelength counterpart, suggesting polar ejecta
launch from the system. Understanding the event with complimentary
high energy observations would shed critical light on neutron star
disruption process by a BH and ultimately allow us to understand the
state of matter and NS composition. Swift initially carried out 451
triggered observations of the LVC region with no counterpart. We dont
see a Swift counterpart in todays observation.

Sequence Number: 300466

Title : The recurrent nova outburst of V3890 Sgr
PI: Orio
Abstract: The symbiotic recurrent nova (RN) V3890 Sgr is having its third known
outburst. Symbiotic RN are strong X-ray sources since the first days.
The Chandra HETG spectrum of RS Oph on day 13 showed strong emission
lines of a multi-temperature plasma, due to the red giant wind
shock-heated by the new, "violent" outflow (Nelson et al. 2008, ApJ
637, 1067; Ness et al. 2009, ApJ 137, 3414). The derived plasma
temperature and the emission line profile are used to constrain the
mass of the ejecta and the outflow geometry, as done by Drake et al.
(2015, ApJ 825, 95) and Orlando et al. (2017, MNRAS 464, 5003) for the
outburst of V745 Sco. In RS Oph and V745 Sco, both hosting massive
white dwarfs, the ejected mass was lower than the accreted envelope,
yielding credibility to symbiotic recurrent novae as a channel to
supernovae Ia explosions. The present outburst of V3890 Sgr will give
important terms of comparison for the outflow models and the possible
path to SN Ia.

Sequence Number: 300465

Title : Catching the return to quiescence of a classical nova post-explosion
system: the unique opportunity for V1369 Cen
PI: Drake
Abstract: The central role of a thermonuclear runaway and explosive envelope
ejection in classical novae (CN) is well established but how, and if,
the system relaxes back to its pre-CN state is unknown. The immediate
aftermath, when accretion restarts and a disk reappears, is crucial
for the initial conditions for any subsequent explosion and the
presumed path toward the cataclysmic variable stage. Understanding
this vital phase requires observing fresh post-CN systems, where
X-rays are essential for diagnosing renewed accretion. This is
extremely difficult because CN are usually distant, obscured and very
faint. CN V1369 Cen 2013 is the best chance to make these
observations. Recent optical-NIR VLT spectra indicate a disk-like
structure is reforming, while Swift data show possible evidence of
renewed accretion. However, Swift could be seeing CN ejecta and
spectral quality is too poor to diagnose the source nature. Chandra
can make the crucial observations to understand the state of the
source.

Sequence Number: 402123

Title : Imaging of Swift J1728.9-3613
PI: Miller
Abstract: The SJ has been sent in an email to the Director.

Sequence Number: 402122

Title : Propeller effect in 4U1901+03 - measuring the spectrum after the
transition
PI: Lutovinov
Abstract: We are asking to observe the transient HMXB 4U1901+03, that recently
went into an outburst. XRT observations showed a dramatic decrease in
the source flux - 30 times in 3 days. This sudden dimming is
reminiscent of an onset of the propeller effect similar to other
well-known HMXBs. The source is currently in a low-luminosity state
with the flux of 5e-13 erg/cm2/s (0.5-10 keV). Because of this low
flux we are asking Chandra observations in order to measure the
spectrum of 4U1901+03, a few days after the transition to the
propeller regime to finally confirm it and to determine the spectral
parameters. It also should be noted that there are no a visibility of
this source with XMM-Newton, so only Chandra can help in the solving
the problem. We are asking for the 10 ks observation. Using PIMMS we
estimated that it will be enough to measure accurately the spectral
shape and to understand is it blackbody-like or are there any
deviations from it.

Sequence Number: 402121

Title : HETG Study of Emission & Absorption Lines in X-ray Bursts from 4U
1820-30
PI: Heinke
Abstract: Strohmayer+2019 saw an emission line (1.04 keV) and two absorption
lines (1.7, 3.0 keV) during the peak of NICER PRE bursts from 4U
1820-30. The lines occur reproducibly in multiple bursts, and are
clearly present in each of the 4 brightest bursts. The energies are
4.6% bluer in brighter than fainter bursts; gravitational or
wind-induced shift? NICER cannot resolve the lines (<70 eV). 4U
1820-30 often (but not always) undergoes low/hard states at six-month
intervals, and strong PRE bursts. NICER has seen bursts every 7 ks in
the last 10 days. The burst lines appear in the PRE phase, ~0.7
seconds each. Simulating these lines (HETG MEG), a single burst is
insufficient; we estimate five PRE bursts will give a >3 sigma
measurement of the 1.7 keV absorption line and 1.04 keV emission line
(the 3 keV absorption feature would likely be only marginally
detected). For a burst every 10 ks, 50 ks should give 5 bursts,
allowing clear HETG detections and measurements.

Sequence Number: 402121

Sequence Number: 503149

Title : The Extended Circumstellar Environment of SN 2003gk
PI: Patnaude
Abstract: The mass loss history of massive stars is one of the least understood
yet fundamental aspects of massive stars. Supernovae shocks, evolving
on timescales of years, allow us to probe 100s to 1000s of years of
stellar evolution, including the crucial time leading up to core
collapse. The X-ray emission from this interaction informs us on the
density and extent of the circumstellar environment, and can provide
clues as to how and when massive stars lose their envelopes, and if
the timing is related to the subsequent core collapse. Observations of
some stripped envelope SNe indicate that the CSM interaction is
delayed, suggesting that the mass loss event occurs on timescales <
10,000 yrs before core collapse. This is in contrast to other Type II
SNe, which can show immediate, strong interaction (IIn) or weak,
extended CSM interaction (IIP/L), suggesting that they type of CSM
interaction is related to the SNe subtype, and may point to a
relationship between progenitor and SN type.

Sequence Number: 703897

Sequence Number: 703896

Sequence Number: 402117

Title : The Microquasar GRS 1915+105 in an Unprecedented Quiet State
PI: Miller
Abstract: Right now, GRS 1915+105 is in an unprecedented state: it is 20-50
times fainter in X-rays than typically measured. The source has never
been this faint, and nor for such a long period, in the entire history
of RXTE, Swift, and MAXI monitoring. This state has persisted for
several weeks, but there is no indication for how long it may last. A
Swift XRT snapshot on 4/23 confirms that the source now has a flux of
just 50 mCrab, or about 1 E-9 erg/cm2/s, in the 1-10 keV band. In a
normal state, GRS 1915+105 is observed at 500-2000 mCrab. This
spectrum is itself quite odd, consistent with a very hot blackbody (kT
= 2.4 keV). The most recent MAXI data suggest the flux is a factor of
~2 lower on 4/24. GRS 1915+105 can be observed with the HETGS without
CC mode, and without blocking the zeroth order. This will permit a
spectrum of an unprecedented state in a critical source, and an
examination of the local jet-impacted environment through imaging.

Sequence Number: 703892

Title : The X-ray obscured quasar J085051: Dust free gas or an eclipse?
PI: Civano
Abstract: Typically, luminous broad line quasar show no or minimal obscuration
in the X-ray band. A small percentage (3%) of X-ray survey selected
sources present broad optical emission lines and mild X-ray
obscuration, supposedly due to dust-free gas not obscuring the broad
line regions. However, given the non simultaneity of the data, a
simple explanation could be that these sources are transitioning from
obscured to unobscured due to e.g. transiting obscuring clouds. The
SDSS broad line quasar J085051 (z=0.66) was recently selected as CCT.
While a bright unobscured spectrum was expected, we observed 60 counts
(0.5-8 keV) and high obscuration (NH=7x10^22pm2.5). We obtained 2 new
optical spectra with the FAST and MDM spectrographs (within 15 and 30
days respectively from the X-ray obsid). Very interestingly we measure
a change in the spectral slope, with the source getting bluer
(difference between the new FAST/MDM spectra and SDSS is m~0.75 at
4300A), confirmed also by new g and r photometry.

Sequence Number: 703887

Title : Chandra observation of the gravitationally lensed balzar PKS 1830-211
during its brightest outburst
PI: Buson
Abstract: PKS 1830-211 is a gravitationally lensed blazar at z~2.5 with two
images at ~1" separation which are well resolved in the two earlier
Chandra HETGS images. Previous observations show strong NH variations
due to variable obscuration in the source. PKS1830 is currently
undergoing its brightest and longest outburst at gamma-rays and
X-rays. INTEGRAL-IBIS gives a 20-50 keV flux of around 6e-11cgs, ~10x
brighter than during the archival Chandra observations. There is short
term variability. We are monitoring the flare with XRT and Fermi, but
these do not resolve the lensed source images. Macro-lensing and
micro-lensing has been detected in this system. The measurement of the
magnification ratio is of special interest given the contradictory
values found with radio and gamma observations. The 3 Chandra
observations of ~20ks each, which should provide spectra that are much
higher SNR than the archival observation, will allow us to determine
NH and the spectral index for both images.

Sequence Number: 703886

Sequence Number: 703885

Sequence Number: 201266

Title : The Origin and Impact of Flares in the Proxima Centauri Planetary
System
PI: MacGregor
Abstract: M dwarfs are the most abundant stars in the galaxy and have a high
frequency of Earth-size planets, making them favored targets of
missions to detect/characterize exoplanets. However, these stars
exhibit high levels of activity, raising questions about the
habitability of their planets. We recently detected a large flare from
Proxima Cen with ALMA (MacGregor et al. 2018) that raises questions
about the relationship between particle acceleration and plasma
heating during flares. To explore this further, we are conducting a
multi-wavelength monitoring campaign of Proxima Cen involving ground-
and space-based facilities. Measuring X-ray flaring energies is
critical, since high energy radiation can erode a planet's atmosphere
by photodissociating water and ozone. We propose to obtain
simultaneous coverage with Chandra to constrain the X-ray properties
of detected flares and their impact on planetary habitability, and to
determine how flaring emission correlates across the EM spectrum.

Sequence Number: 201265

Sequence Number: 703879

Title : Exploring the possible link between mass ejection and X-ray emission
in a nearby TDE
PI: Alexander
Abstract: AT2019ahk is a rare nearby (110 Mpc) candidate tidal disruption event
(TDE) discovered on 29 January 2019. This source was detected
unusually early (1 month before peak optical light), allowing for
excellent constraints on the properties of the disrupting SMBH and
detailed followup with Swift and ground-based facilities. Our ALMA
observations of this event reveal the first detection of mm emission
from an optical TDE, a signpost of mass ejection. XRT reveals the
event to be X-ray faint, with implications for a proposed radio/X-ray
correlation in radio TDEs. Here, we propose Chandra observations to 1)
determine the temporal behavior of the X-ray source and establish a
link to the UV/optical and mm evolution; 2) use Chandra's superior
angular resolution to pinpoint its location and determine whether it
is point-like (as expected for a TDE) or extended. AT2019ahk provides
a unique opportunity to test models of SMBH accretion and to study the
entire lifecycle of a weak SMBH jet.

Sequence Number: 703878

Sequence Number: 100182

Title : Chandra-HRC Support for Juno-UVS on Attitude Adjustment Perijoves
PI: Gladstone
Abstract: To study the morphology and physics of Jupiter's auroral x-rays,
through comparison with simultaneous Juno-UVS remote sensing and
Juno-JADE and Juno-JEDI in-situ particle observations. The best Juno
data for Jupiter's northern aurora are now obtained during specific
"attitude adjustments" perijoves, which are only scheduled a few
months ahead of time. Jovian auroral x-rays are associated with a
region of UV emission known as the active region, which likely
coincides with the return current connected with the main auroral
oval. Juno-JEDI provides useful measurements of O ion precipitation,
but only along the magnetic footprint of Juno. Simultaneous maps from
Chandra provide highly scientifically useful supporting observations
for Juno.

Sequence Number: 402115

Title : Determining the X-ray Position of 4U 1901+03
PI: Hemphill
Abstract: Transient X-ray pulsars are excellent laboratories for studying
accretion and binary evolution, due to the large luminosity changes
during an outburst. However, these outbursts are typically infrequent
and aperiodic, often with years or decades between events. For this
reason, many systems are relatively poorly studied. One vital
measurement is the localization of the X-ray source, as this enables
the identification and classification of the optical counterpart, the
donor star, the properties of which are of supreme importance for
understanding the evolution of the system and interpreting the X-ray
spectra and variability of the source. 4U 1901+03 has just begun its
fourth outburst in history, but currently the best position is the
RXTE/PCA 1' error circle, so the optical counterpart is still
unknown.

Sequence Number: 703863

Title : Extraordinary 9 hours quasi-periodic X-ray outbursts from an accreting
SMBH
PI: Miniutti
Abstract: We have observed the Seyfert galaxy GSN 069 on 2018-12-24 with XMM and
discovered two extraordinary X-ray flares spaced by ~30ks. No flares
were detected back in 2014 during a 80 ks XMM observation. We obtained
a further long XMM DDT on 2019-01-17, and obtained 5 extraordinary
quasi-periodic flares separated by ~32ks. This beaviour is unlike
anything seen before in AGN and potentially represent a Rosetta-stone
for our understanding of SMBH accretion and/or dynamics. GSN 069 is
either a re-activated AGN after a long period of quiescence or
(perhaps more likely) a long-lived Tidal Disruption Event.
Interpretations for the extraordinary observed behaviour include GR
precession of the innermost flow, a very close separation SMBH binary
system etc. We need to use the Chandra current visibility window (no
XMM observation is possible now) to follow-up this extraordinary
system and start to constrain the interpretation. More details in the
uploaded PDF science case.

Sequence Number: 402114

Title : Revealing the SXP 4.78 transition in to the 'propeller mode'
PI: Lutovinov
Abstract: One of the most straightforward manifestations of the interaction of
matter with the magnetosphere of a neutron star is a transition of the
accreting neutron star to the so-called propeller regime (Illarionov &
Sunyaev 1975), when the accreting matter is stopped by the centrifugal
barrier set up by the rotating magnetosphere. Such a transition is
expected to occur at the limiting luminosity defined by the dipolar
magnetic field strength and rotation rate of the pulsar. Confident
detection of such a transition provides a completely independent
estimate of the magnetic field of the pulsar and in general allows for
a better understanding of the interaction of the accretion flow and
magnetosphere (Tsygankov et. al. 2016). Measured limiting luminosity,
confirmed with the low flux and changed spectrum in SXP 4.78 will be
utilized to determine magnetic field strength, yet unknown for this
system.

Sequence Number: 703841

Title : Timely Assessment of the X-ray Flux of Newly Discovered Quadruply
Lensed Quasars
PI: Pooley
Abstract: Our previous work has shown the unique power of Chandra observations
of quadruply gravitationally lensed quasars to address several
fundamental astrophysical issues. We have used these observations to
(1) determine the cause of flux ratio anomalies, (2) measure the sizes
of quasar accretion disks, (3) determine the dark matter content of
the lensing galaxies, and (4) measure the stellar mass-to-light ratio
(in fact, this is the only way to measure the stellar mass-to-light
ratio beyond the solar neighborhood). In all cases, the main source of
uncertainty in our results is the small size of the sample of known
quads; only about 15 systems had been available for study with Chandra
unti the past year or two. New, large-area sky surveys have produced a
trove of new quads, and timely Chandra observations will allow for
great progress. We aim to propose such observations in the coming
cycle and seek to assess the unknown X-ray flux now in order to
propose the most efficient GO program.

Sequence Number: 703840

Sequence Number: 703839

Sequence Number: 703838

Sequence Number: 703837

Sequence Number: 703836

Sequence Number: 703835

Sequence Number: 703834

Sequence Number: 703833

Sequence Number: 201264

Title : A disk event in an Oe star
PI: Rauw
Abstract: Massive stars, including those with decretion disks (i.e. Oe and Be
stars), have an intrinsic X-ray emission linked to shocks in their
unstable winds with kT~0.6keV & log(Lx/Lbol)~-7. However,gamma-Cas
objects, named after their prototype, are substantially X-ray brighter
and emit harder X-rays. The origin of their high-energy emission
remains debated, but our recent observation of HD45314 during a
dissipation of its disk revealed an exceptional event: the X-ray
mission went 'back to normal', underlining the key role of the disk in
this poorly known phenomenon. However, to fully constrain it, the
inverse process (a 'normal' star becoming gamma-Cas) should also be
detected... but it has never been reported before.

Sequence Number: 402113

Title : A multi-wavelength ATCA/GAIA/Chandra search for the weakest Jets
PI: Reynolds
Abstract: Herein, we propose to obtain a 20ks Chandra imaging spectroscopy
observation of the dynamically confirmed BH GS 1354-64 to occur
quasi-simultaneously with an approved and scheduled ATCA radio
observation. Previous Chandra studies have revealed an anomalous high
luminosity quiescent accretion flow in this source (Reynolds et al.
2011). A new lower distance to the source has been proposed based on
GAIA parallax measurements (Gandhi et al. 2018). This new distance
would resolve the X-ray luminosity issue if the distance is closer to
2 kpc. At the GAIA distance the radio jet is easily within reach by
ATCA. A radio detection will provide valuable information on the
correct distance, and an additional constraint on the radio/X-ray
correlation at the lowest luminosities. Quiescent BHXBs are known to
be highly variable (F_var~60% in both the X-ray and radio), such that
a rigorous interpretation of a radio detection is impossible without
contemporaneous constraints on the X-ray flux.

Sequence Number: 402112

Title : Verifying a hyperluminous X-ray source in the spectroscopically
studied young starburst ESO 338-IG04
PI: Oskinova
Abstract: The enigmatic hyperluminous X-ray sources (HLXs) are off-nuclear point
sources with Lx> 10^{41} erg/s. HLXs probe different population of
compact objects compared to other accretors, and likely contain
intermediate mass black holes. Only a handful of HLX candidates is
known. The identification of a HLX in a galaxy with well characterized
stellar populations is the key to unlock a range of astrophysical
problems, such as the escape of ionizing radiation, stellar feedback,
double black hole formation, intermediate mass black holes in star
clusters, the lowest AGN masses and luminosities. From XMM images we
found that the low-metallicity starburst galaxy ESO 338-IG04 hosts a
candidate HLX. The stellar population of ESO 338-IG04 is already
thoroughly investigated thanks to the integral field spectroscopy with
MUSE at ESO VLT (Bik et al. 2018 arXiv:1809.03597). Here we seek to
determine the X-ray position of the new HLX and unambiguously identify
its optical counterpart.

Sequence Number: 201263

Title : Characterizing the X-ray Driven Chemistry of Protoplanetary Disks in
Orion
PI: Cleeves
Abstract: Young stars are surrounded by molecule-rich protoplanetary disks whose
chemistry is expected to evolve slowly, over ~Myr. Hence, we were
surprised to discover variability in H13CO+ J=3-2 emission from the IM
Lup disk between 3 observations taken over one year. This molecule is
X-ray sensitive, and a natural explanation is that stellar X-ray
flares may drive large changes in the disk composition. We have
followed up on a second source, DM Tau, and indeed see variations
consistent with X-ray driven disk chemistry but still lack the
"smoking gun" of an X-ray flare preceding H13CO+ variability. We have
recently obtained Swift and ALMA time to monitor 10 disks in Orion,
and here propose to obtain X-ray spectral shape info with Chandra.
Using simulations, we estimate a 93% probability of seeing H13CO+
variability preceded by an X-ray change for at least one source in our
sample. If confirmed, these observations will be the start of an
entirely new field of time-domain astrochemistry.

Sequence Number: 201262

Sequence Number: 703832

Title : Witnessing the Birth of a Blazar
PI: Paliya
Abstract: Gamma-ray detected narrow line Seyfert 1 (g-NLSy1s) galaxies are the
missing link between radio-quiet AGN and blazars. It is tedious to
study the host galaxy environment in blazars due to their jet
dominated emission. Therefore, g-NLSy1s, being lower jet power
objects, are the only beamed AGNs to unravel the jet-host galaxy
interaction. We have imaged the host of a g-NLSy1, TXS 2116-077, with
Subaru telescope and have discovered that the host is in the act of
merging with a nearby faint AGN (sep ~3", https://goo.gl/xdc1nZ).
Theoretically, it has been predicted that most jets are triggered by
mergers but this would be the very first observational evidence of it.
TXS 2116-077, thus, is a rare AGN to verify the theories of the jet
triggering mechanism. Our immediate objectives are: (i) determine the
X-ray morphology of the merging system and perform a spatially
resolved X-ray spectral analysis, and (ii) identify the nature of the
second nucleus (obscured/unobscured).

Sequence Number: 300461

Title : Target Confirmation for the Great Observatories Accretion Legacy
Survey
PI: Knigge
Abstract: Accretion disks power YSOs, LMXBs, CVs and AGN. The accretion process
often proceeds in bursts, during which systems brighten dramatically.
Remarkably, all transient disk-accretors share common observational
signatures: distinct spectral states, collimated jets, powerful disk
winds and analogous variability. To uncover the universal physics
behind this shared phenomenology, we are planning the Great
Observatories Accretion Legacy Survey. GOALS will observe a
disk-accreting system through a full outburst, with near-continuous
panchromatic coverage from X-ray to radio wavelengths. A viable target
for GOALS must (i) exhibit repeatable outbursts of suitable duration,
and (ii) be bright in all relevant bands. Only transiently accreting
CVs satisfy (i). Satisfying (ii) then requires a CV with detectable
EUV (critical for the soft state in CVs) and radio emission (the only
way to detect jets). Here, we propose a confirm the EUV suitability
(for LETG) of the only viable target we know.

Sequence Number: 503140

Title : The Compact Remnant in the Extraordinary Type Ib SN 2012au
PI: Patnaude
Abstract: Models of hydrogen-poor and energetic core-collapse supernovae often
invoke engine-driven mechanisms associated with the formation of
compact objects that input energy into the explosion. Determining
whether black holes or neutron stars play key roles in these
explosions remains contentious, as only circumstantial evidence of
their formation can be obtained when the explosion is most luminous. A
recent Magellan IMACS spectrum of the Type Ib SN 2012au revealed the
presence of photoionized, low velocity (2000 km/s) ejecta, with no
evidence for emission from the outer layers of fast moving ejecta. We
hypothesize that the inner layers of ejecta are being energized by a
luminous central source formed during the supernova. X-ray
observations will test this hypothesis. If the optical emission arises
from circumstellar interaction, it should be accompanied by X-rays
from shocked material. A non-detection will strengthen our argument
that the ejecta are energized by a central source.

Sequence Number: 503053

Title : A possible off-axis GRB in a nearby galaxy
PI: Maccarone
Abstract: This object is a bright X-ray transient in a galaxy at 60 Mpc,
consistent with expectations for a GRB afterglow, but without a GRB
having been seen. Its X-ray spectrum is harder than Gamma=2, but its
X-ray flux is below its optical flux, meaning that these are two
separate components. We thus need to extend the continuum in the
X-rays to get an idea of where the spectral curvature is.
Unfortunately, it cannot be observed by NuSTAR or INTEGRAL right now,
but fortunately it is bright enough to extend down in energy a factor
of 5 by using the LETG. We will also look for emission lines that
might indicate an optically think outflow and absorption lines that
might help characterize its local ISM.

Sequence Number: 201206

Title : Beyond the Coronal Graveyard
PI: AYRES
Abstract: Iconic Arcturus is member of a populous class of low-mass red giants
whose warm winds are a life-blood of Galactic ecology. How their mass
outflows are powered has remained elusive. A solar-like coronal wind
seemed unlikely, because the red giants have a very low incidence of
high-energy detections. In fact, Arcturus, itself, is one of the
weakest X-ray sources known among the bright cool stars. An intriguing
possibility is that red giants do have significant magnetic activity
and coronae, but mostly hidden beneath their puffy chromospheres.
Unfortunately, the X-ray spectra that could test the "buried corona"
conjecture are beyond reach of contemporary facilities. However, a
new, robust X-ray detection of Arcturus would inform the next
generation of high-energy observatories, whether such advanced
measurements in fact would be feasible.

Sequence Number: 703679

Title : Probing the duty cycle of a nuclear intermediate mass black hole
accreting at the Eddington limit
PI: Chilingarian
Abstract: Intermediate mass black holes represent (IMBH) a missing block in the
understanding of supermassive black hole assembly. Their very
existence is still debated. Using comprehensive multi-wavelength data
mining we identified 305 IMBH candidates by searching AGN signatures
in optical spectra of 1 million galaxies from SDSS. In 2017 we
followed up two of the candidates with Chandra and detected bright
X-ray emission from one of them, which corresponded to the level close
to the Eddington limit for its mass (70k MSun). This is the least
massive known active central black hole that has an X-ray spectrum.
Here we propose to observe this source once again in order to get the
first insights on the duty cycle of an IMBH-powered AGN. In 10ksec we
expect 500 photons from the source if the luminosity is persistent,
which we suspect is true given the lack of optical variability of the
broad-line component of H-alpha.

Sequence Number: 703678

Title : Chandra observations of NGC3893: Completion of the Palomar Galaxies
Legacy Sample
PI: McHardy
Abstract: In proposal 18620515 we were awarded observations to complete Chandra
coverage, to 10ks per target, of ALL of the galaxies from the Palomar
bright nearby galaxies sample of Ho et al (1995) in the declination
range +40 to +65. This sample is widely regarded as the statistically
most complete sample of nearby galaxies and is the subject of 'legacy'
surveys in many bands. In particular we made high resolution (0.15
arcsec) eMERLIN radio observations of all the above galaxies, not just
those classed as active, as in other studies. Only Chandra provides
comparable X-ray resolution. Thus we should be able to study
relationships such as the radio/X-ray/BH mass 'fundamental plane', or
derive X-ray luminosity functions at very low luminosities, for
different galaxy types without any concerns regarding incompleteness.
We selected our Chandra sample to avoid duplication and erroneously
removed one galaxy. We here request one 10ks observation to make the
Chandra legacy sample 100% complete.

Sequence Number: 402025

Title : GW170817: Long term tracking of the the X-ray light curve.
PI: Wilkes
Abstract: This proposal is a merger of several DDT requests to follow-up the
NS-NS merger: GW170817.

Sequence Number: 402026

Title : Wind energetic and dust scattering halo in Swift J1658.2-4242
PI: Ponti
Abstract: SwiftJ1658.2-4242 is a newly discovered high inclination BH-XRB. We
obtained 5*30ks XMM+NuSTAR+3*30ks AstroSAT campaign following the
evolution of the wind and the accretion systems from the hard to the
soft intermediate state (Feb. 27-Mar. 27). The source shows never-seen
Compton thick dips and a behaviour observed only in few systems and of
unclear origin. This appears as sudden (<50s) drops/increases
(flip-flop) of the flux, with weak colour variations and non-periodic.
A QPO at 6Hz is observed at lower flux and it disappears at high flux.
A variable absorption line at ~7 keV +a relativistic FeK line are
observed to evolve during the outburst. We request a 30ks HETG
observation during the current soft state to: A) Determine the
energetics of the wind, investigate its relations with the states and
flip-flop behaviour; B) Disentangle absorption from relativistic line;
C) Detail the inner parts of the dust scattering halo; D) Determine
the amount of Iron depleted into dust grains.

Sequence Number: 503043

Title : Zeroing in on the Mass Loss Properties of Core Collapse Supernova
Progenitors
PI: Patnaude
Abstract: The mass loss history of massive stars is one of the least understood
yet fundamental aspects of stellar evolution. How and when do massive
stars shed their hydrogen envelopes? Is there a relationship between
the expulsion of the stellar envelope and core collapse? Is there a
fundamental relationship between late time mass loss and supernova
classification? These central, yet open questions motivate the
proposed Chandra Successor Mission program. In regards to these
questions, studying the evolution of a supernova shock, over
timescales of decades, as it interacts with the ejected envelope of
the progenitor, provides insight into how much mass was lost and
perhaps most importantly, when it was lost, prior to core collapse.
X-ray emission from the shocked gas probes the dynamics of the
interaction, and when combined with multiwavelength observations,
constrains properties of the surrounding circumstellar gas and thus
the later stages of the progenitor's evolution.

Sequence Number: 402025

Title : GW170817: Long term tracking of the the X-ray light curve.
PI: Wilkes
Abstract: This proposal is a merger of several DDT requests to follow-up the
NS-NS merger: GW170817.

Sequence Number: 703677

Title : Origin of the X-ray to TeV emission of the M87 AGN
PI: Wong
Abstract: M87 hosts a 3-6 billion solar mass black hole with an exceptional
relativistic jet. It has been regularly monitored in radio to TeV
bands, but little has been done in hard X-rays >10 keV. For the first
time, we have successfully detected hard X-rays up to 40 keV from its
X-ray core with joint Chandra and NuSTAR observations, providing
important insights to the X-ray origins (Wong et al. 2017): from the
unresolved jet or the accretion flow. We found that the hard X-ray
emission is significantly lower than that predicted by synchrotron
self-Compton models introduced to explain emission above a GeV. To
further understand these high energy processes, a key component is to
monitor the soft and hard X-ray emission and study their correlation.
Together with the Event Horizon Telescope, NuSTAR will observe M87 in
April 2018. We propose Chandra snapshots near the NuSTAR window, which
is essential to resolve the keV jet and to pin-point the location of
the high energy active site.

Sequence Number: 703676

Sequence Number: 703675

Title : Determining the emission region of VHE gamma-rays in radio galaxy 3C
264
PI: Santander
Abstract: We request DDT observations of the radio galaxy 3C 264, which VERITAS
is currently observing in an active state that has led to its first
detection in VHE gamma-rays. The analysis of the VHE observations is
on-going and VERITAS plans to perform a deep exposure of the object
over the coming days. This detection would represent the 6th radio
galaxy observed in VHE gamma rays. Radio galaxies are currently the
only non-blazar AGN detected in this band. As the jet of 3C 264 has
been resolved by Chandra, this detection presents a unique opportunity
to determine the location of the VHE gamma-ray emission region and
differentiate its origin with the core and inner jet, or the outer
resolved jet. A MWL campaign is being organized for the source.

Sequence Number: 503052

Title : MAPPING OUT THE EXPLOSIVE MASS-LOSS HISTORY OF THE IMPOSSIBLE SN
iPTF14hls
PI: MARGUTTI
Abstract: The stellar explosion iPTF14hls has been confusing the community for a
while, with a spectral and temporal evolution that could not be
reconciled under standard scenarios. However, iPTF14hls recently
experienced a complete spectral metamorphosis. This evolution suggests
that the solution to the puzzle might be the interaction of the
blastwave with an environment sculpted by the progenitor's eruptions
before the final explosion. If this is correct, iPTF14hls should
produce rising X-ray and radio emission in the next months. Here we
ask for CXO monitoring to test our interacting scenario.

Sequence Number: 703674

Title : LOW SURFACE BRIGHTNESS GALAXIES AND THE BLACK HOLE OCCUPATION
FRACTION
PI: Gallo
Abstract: We propose a snapshot survey of nearby low-surface brightness galaxies
(unbiased with respect to nuclear properties) to measure the rate and
incidence of low Eddington ratio nuclear X-ray emission and determine
how the nuclear L_X to mass (stellar and/or gas) relation in this
sample compares with that of normal, high surface brightness galaxies.
Results from this program will inform the galaxy selection function
needed towards a high accuracy black hole occupation fraction
measurement with Lynx. In turn, this will constrain the primary mode
for black hole seeding at high z, complementing efforts that will be
undertaken at high-z.

Sequence Number: 703673

Sequence Number: 703672

Sequence Number: 703671

Sequence Number: 703670

Sequence Number: 703669

Sequence Number: 703668

Sequence Number: 703667

Sequence Number: 703666

Sequence Number: 703665

Sequence Number: 703664

Sequence Number: 703663

Sequence Number: 703662

Sequence Number: 703661

Sequence Number: 703660

Sequence Number: 703659

Sequence Number: 703658

Sequence Number: 703657

Sequence Number: 703656

Sequence Number: 703655

Sequence Number: 703654

Sequence Number: 703653

Sequence Number: 703652

Sequence Number: 703651

Sequence Number: 703650

Sequence Number: 703649

Sequence Number: 703648

Sequence Number: 703647

Sequence Number: 503051

Sequence Number: 503050

Sequence Number: 503049

Sequence Number: 503048

Sequence Number: 503047

Sequence Number: 503046

Sequence Number: 503045

Sequence Number: 503044

Sequence Number: 503043

Sequence Number: 201206

Sequence Number: 402024

Title : Killing two birds in NGC 5907 with one stone: possible dust scattering
halo in ULX1 and the newly discovered ULX2
PI: Pintore
Abstract: NGC 5907 contains two transient ULXs (separated by 28"), with ULX1
being the most extreme ULX pulsar. In the last Chandra observation,
ULX1 was weak (Lx~2e38 erg/s) and surrounded by diffuse X-ray emission
of radius ~3". It could be a scattering halo from dust in NGC 5907 of
the previous ULX1 high state. This can be proved by observing the flux
decrease expected in this case. A negative result is still interesting
since this would be the only ULX with a persistent X-ray nebula. We
discovered ULX2 at a peak luminosity of ~6e39 erg/s, with a multicolor
blackbody disc spectrum, reminiscent of the soft state of Galactic
accreting black holes (BHs). Hence ULX2 may possibly host a 30 Msun BH
accreting at <= Eddington rates. The source is now decaying below the
ULX regime and, if correctly interpreted, we expect a spectral
transition to a hard powerlaw spectral shape. The current state of the
two targets gives the opportunity to achieve both goals with a single
Chandra observation.

Sequence Number: 402024

Sequence Number: 201205

Title : Alpha Centauri: Mind the Gap!
PI: AYRES
Abstract: Cycle 19 proposal to continue long-term monitoring of coronal X-ray
activity cycles of sunlike Alpha Centauri A (G2V) and B (K1V) was not
approved. New Cycle 20 request will address panel's concerns. Even if
Cycle 20 proposal is approved, still will be unpleasant gap in the
semi-annual coverage, ongoing since 2005. Long-term HRC X-ray series
on AlpCen is unique, fundamentally important: key contribution of
Chandra to understanding cycling "Dynamos" of late-type stars, high
scientific priority in solar-stellar physics. Although stellar cycles
are known from CaII monitoring, X-rays contribute uniquely owing to
50X larger contrast at high-energies. A 5 ks pointing in mid-2018
would fill the gap. In fact, most recent AlpCen-A L_X (Ayres: 2018,
RNAAS) shows a possible, unusual, rapid downturn, in the declining
phase of its cycle (previous decline 2001-05 missed by lack of
observations). Only Chandra can resolve AB at present.

Sequence Number: 402022

Title : Measure spin-up of NGC 300 ULX-1
PI: Vasilopoulos
Abstract: NGC 300 ULX-1 is a newly identified ULX pulsar. The system has shown a
extraordinary spin up rate within the last year, when it spun-up from
31 sec to 20 sec. We request 2x10 ks chandra observations separated by
2-4 days in order to accurately measure the spin up rate of the
pulsar.

Sequence Number: 402021

Sequence Number: 402020

Title : GW170817: Tracking the X-ray light curve to study the origin of the
emission
PI: Wilkes
Abstract: Continued tracking of the light curve of this unique NS-NS merger to
understand the emission mechanisms and the structure. We will include
the proposing DDT teams as co-Is on this proposal. They will all have
access to the data, but this proposal does not require that they work
together.

Sequence Number: 402020

Sequence Number: 402019

Title : Detecting X-ray emission from a very massive black hole binary
PI: Liu
Abstract: Our most recent work with LAMOST spectroscopic survey has revealed a
black hole candidate with a B companion, which can be more massive
than 40 solar masses judging from the relative motion of the B
companion (from its absorption lines, with a radial velocity
semi-amplitude of 50km/s) and the black hole (from its broad strong
Halpha emission line, with a semi-amplitude below 10km/s). About 20
LAMOST low resolution spectra taken in two years have revealed its
binarity with a period of 70 days, and GAIA data also confirms its
binarity independently. We have launched a GTC/OSIRIS campaign to take
20 spectra in two months, and a Keck/HIRESr campaign to take 18
spectra in two months, to fine sample its 70-day period and better
determine the binary properties. . Here we propose a 10ksec Chandra
exposure to detect its X-ray emission.

Sequence Number: 703470

Title : The X-rays of a bright QSO well within the epoch of reionization at
z=7.54
PI: Banados
Abstract: After almost a decade of intense search, our team has finally
discovered a bright QSO well within the epoch of reionization, at
z=7.54. This is by far the most distant QSO known (previous record:
7.08), at a cosmic age of 690 Myr, i.e., only 5% of our universe's
current age. This is the first QSO whose spectrum shows clear evidence
of an intergalactic medium that is >20% neutral and that reionization
is underway. We propose Chandra observations of this unique object to
(i) probe evolution of the X-ray-to-optical luminosity ratio
(alpha-ox) to the highest accessible redshift; (ii) provide a more
reliable estimate of the QSO's bolometric luminosity, and (iii) assess
the feasibility of deeper Chandra and XMM observations for the
upcoming cycles, which would allow us to test whether the first black
holes are accreting at super-Eddington rates.

Sequence Number: 201204

Title : Characterizing X-ray driven molecular chemistry in a young
protoplanetary disk
PI: Cleeves
Abstract: Young (Myr-old) stars are both X-ray luminous and variable.
Surrounding the star is a molecule-rich protoplanetary disk whose
chemistry is expected to evolve slowly, over $\sim0.01-1$ Myr. In this
context, ALMA provided a curious puzzle when we discovered short-term
variability in the H13CO+ J=3-2 line across three observations of a
disk taken over just a single year (Cleeves et al. 2017). One
explanation is stellar X-ray activity perturbing the chemical ``steady
state'' of the disk, where HCO+ is a known X-ray sensitive molecule
(Cleeves et al. 2014). We were recently awarded SMA time to test the
X-ray driven variability hypothesis (one observation every 6-7 days
for 2 months) by measuring the magnitude and frequency of H13CO+
variability. We propose here to compliment these SMA observations with
Chandra monitoring to directly connect for the first time the
time-varying X-ray state of the star to the composition of the
planet-forming disk.

Sequence Number: 201203

Sequence Number: 201202

Sequence Number: 201201

Sequence Number: 201200

Sequence Number: 201199

Sequence Number: 201198

Sequence Number: 402012

Title : GW170817: Tracking the X-ray light curve to study the origin of the
emission
PI: Wilkes
Abstract: This proposal is a merger of several DDT requests to follow-up the
NS-NS merger: GW170817 as it comes out of sunblock. We will include
the proposing DDT teams as co-Is on this proposal. They will all have
access to the data, but this proposal does not require that they work
together.

Sequence Number: 402012

Sequence Number: 402011

Title : Searching for outflows from a nearby super-Eddington accreting neutron
star
PI: Degenaar
Abstract: Swift J0243.6+6124 is a newly discovered Be/X-ray binary that harbours
a 9.8-s pulsar and went into outburst 30 days ago (ATel #10809). It
has been brightening since and reached super-Eddington luminosities on
Nov 1 (Lx~4E38 erg/s), which have been sustained since then (Lx~E39
erg/s on Nov 6). Accretion at super-Eddington rates is predicted to be
associated with strong outflows, both jets and disk winds. Testing
this idea is challenging because super-Eddington accreting neutron
stars are located in other galaxies. However, Swift J0243.6+6124 is
located at a distance of only 4 kpc (Doroshenko et al. 2017,
arXiv:1710.10912). This provides a unique opportunity to study
outflows in the super-Eddington accretion regime. We have secured VLA
radio observations (PI van den Eijnden) to search for a jet. Here, we
request Chandra/HETG observations to look for highly blue-shifted,
ionized absorption features at high (>5 keV) energy that would reveal
a disk wind.

Sequence Number: 801803

Title : The most distant X-ray luminous cluster discovered by ROSAT
PI: Ebeling
Abstract: We propose a short ACIS-I observation of eMACSJ0324, the most distant
massive cluster discovered to date by ROSAT, confirmed in Sep 2017 to
be at z=0.901 (8 redshifts). At 1.4e^45 erg/s (0.1-2.4 keV), our
target is as X-ray luminous as the giant galaxy clusters (and HFF
targets) MACSJ0416, MACSJ1149, or MACSJ0717 - but at twice the
redshift. If eMACSJ0324 is confirmed to be as massive as its more
nearby, famous siblings (its present X-ray luminosity estimate is
based on 10 RASS photons), it would be one of fewer than a handful
exceptionally massive clusters known at z~1, the first extreme mass
concentrations (>1e^15 M_sun) to decouple from the Hubble flow. Our
DDT request, complemented by an HST Cycle 25 Mid-Cycle proposal, aims
to use Chandra's unparalleled resolution to constrain the contribution
from any point sources to the X-ray flux of eMACSJ0324 as observed in
the RASS, and to obtain a robust measurement of the cluster's total
X-ray luminosity from about 1500 net photons.

Sequence Number: 100171

Title : Uranus During an Interplanetary Coronal Mass Ejection
PI: Dunn
Abstract: While Jupiter's X-ray Aurora was first detected by the Einstein
Observatory, it remains unknown what processes allow it to create the
energies required for soft X-ray Aurorae. Saturn does not produce
detectable X-ray Aurora. Why these 2 rapidly rotating giant planets,
with internal plasma sources, have such different auroral intensities
remains unclear. Saturn's magnetic field is parallel to its rotation
axis, but Jupiter's has a 10-degree tilt, which helps produce large
electric fields. Uranus' magnetic field is at 60 degrees to the
rotation axis, producing ever-varying magnetospheric dynamics and
reconnection. Given that reconnection is the common explanation for
Jupiter's X-ray Aurora, the extent/absence of X-ray Aurora at Uranus
would show the importance of reconnection as a driver. On 10 Nov, an
ICME arrives at Uranus, which will compress the magnetosphere,
increasing reconnection rates. At Jupiter, ICMEs increase X-ray
auroral counts by a factor of 3-6, improving detectability.

Sequence Number: 100171

Sequence Number: 201197

Title : Candidate TDE AT 2017gbl
PI: Heikkila
Abstract: We discovered a very likely Tidal Disruption Event (TDE) AT 2017gbl in
the luminous infrared galaxy (LIRG) IRAS 23436+5257 (ATels 10651,
10712), which are very rare events. The recent discovery of another
TDE candidate in the LIRG F01004-2237 suggests that there is an
enhanced rate of TDEs in LIRGs which would often be missed due to the
large amounts of gas and dust. TDEs can also be extremely bright in
X-rays. We observed AT 2017gbl with Swift, with no source detected and
with upper limit ~4*10^41 erg/s. LIRGs also host a population of X-ray
binaries, and the X-ray luminosity from the host can be estimated from
the IR-luminosity, at least ~ 5*10^40 erg/s in the case of IRAS
23436+5257. By observing down to this limit, we will put strict
constrains on the intrinsic luminosity of the transient, determining
its nature. In addition, this would be the first direct X-ray
detection of IRAS 23436+5257 and important eg. for studying the
SFR-X-ray luminosity relationship in distant LIRGs.

Sequence Number: 402010

Title : Probing the Low State of the Most Extreme ULX Pulsar
PI: belfiore
Abstract: The 3 Ultraluminous X-ray Sources (ULXs) driven by accreting neutron
stars well beyond their Eddington limit (L(Edd)) deserve more
investigation as they constrain accretion in a regime that eludes
simple explanations. They all display superorbital flux modulations
and rarely enter a low state not yet understood, that could shed light
on their physics. The sources could go sub-Eddington, or the
centrifugal push could inhibit accretion (propeller effect), or the
pulsar could be obscured by optically thick material (in a disk or
winds). The most extreme ULX pulsar is NGC 5907 ULX (Israel et al
2017, I17), at 500 times L(Edd). Current observational campaigns with
Swift, XMM-Newton, and NuSTAR have recently seen it entering a low
state (<20 L(Edd)) and no recovery after one superorbital period. Now
only Chandra can probe its low flux, resolving it from other sources
in its galaxy (I17, fig S1; Walton et al 2015), and distinguish a
propeller state (~2 L(Edd)) from other scenarios.

Sequence Number: 503034

Title : X-ray monitoring of GRB170817A
PI: Troja
Abstract: GRB170817A is an under-luminous short GRB possibly located at 40 Mpc
and associated to the peculiar infrared/optical transient SSS17a. Deep
upper limits constrain the presence of an on-axis afterglow. Here we
propose to search for X-ray emission at late times in order to
constrain the presence of an off-axis afterglow and isotropic
electromagnetic counterparts. Due to the proximity to another X-ray
source and the expected faintness of the afterglow fluxes, only the
accuracy and sensitivity of Chandra will allow us to detect the X-ray
counterpart.

Sequence Number: 300403

Title : The late outburst evolution of Nova Lup 2016: a likely solution of
nova 'mysteries'
PI: Orio
Abstract: The decline of Nova Lup 2016 in the supersoft X-ray phase is occurring
more slowly than in most novae, allowing scheduling during a poorly
known phase, important for the models. The nova has been observed at
maximum with XMM and the PI has kindly shared his data; it is now
monitored with Swift. A Chandra LETG exposure would allow: 1) Precise
determination of N(H), differentiating between cooling and spectral
softening due to diminishing intrinsic absorption; 2) Witnessing
whether turn-off is occurring with decreasing flux at almost constant
T(eff) (implying a shrinking, but still hot surface region), as
inferred in some magnetic novae at the beginning of the decline or in
the early quiescence, or whether the WD is isotropically cooling; 3)
Observing whether the residual wind from the compact WD ceases before
the burning is turned off; 4) Measuring absorption and emission lines
due to transitions of intermediate mass ions, constraining chemical
evolution.

Sequence Number: 703616

Title : Deep X-ray follow-up of a TDE candidate
PI: Nicholl
Abstract: The transient PS17dhz shows optical signatures typical of tidal
disruption events (TDEs), including blackbody temperature >30000 K and
broad He II emission. However, the host is unusual: a compact galaxy
with absolute magnitude M_r ~ -18, suggesting that PS17dhz may have a
smaller black hole mass than other TDEs. From Swift data we have found
an optical flux F_opt ~ 10^-13 erg/s/cm2, and an X-ray limit F_X <
10^-13 erg/s/cm2. All optical TDEs with X-ray detections have had
X-ray to optical ratios >~ 1, suggesting that PS17dhz is X-ray faint.
However, there are UV/optical TDEs without X-ray detections ( veiled
TDEs). The lack of X-rays could be due to additional
reprocessing/obscuration around the black hole. The Swift
non-detection suggests that PS17dhz is veiled, but since the Swift
X-ray limit is already close to L_opt, a deeper observation with
Chandra gives one of the best chances to detect weak X-rays from a
veiled TDE.

Sequence Number: 503033

Title : Precise localization of the ultra long high-energy transient
GRB170714A
PI: Troja
Abstract: GRB170714A is a peculiar high-energy transient of ultra-long (>1,000
s) duration. Its nature is still unclear: its high-energy properties
suggest that it could be a relativistic tidal disruption event or a
rare ultralong GRB, produced by an exotic stellar progenitor. Further
multi-wavelength observations are critical to characterize the
explosion properties and its host environment. Tentative optical and
radio counterparts were reported in the literature. However, their
positions differ significantly and might be contaminated by other,
unrelated sources. Chandra observations are critical to improve the
positional accuracy of the X-ray transient, to precisely determine its
position with respect to the underlying host galaxy, and to determine
its association with the putative counterparts.

Sequence Number: 703470

Sequence Number: 703469

Title : X-ray confirmation of two intermediate mass black hole candidates
PI: Chilingarian
Abstract: For the last two decades, the international research community has
been hunting the elusive population of intermediate mass black holes
(IMBHs) crucially important for the understanding of galaxy and BH
co-evolution. Despite several good candidates have been found with
various techniques, it is still unclear whether IMBHs existed in the
early Universe and if there is a common way for them to remain intact
as a population till our epoch. We have performed a comprehensive IMBH
search in nearby galaxy nuclei using their optical spectral signatures
(broad Halpha+BPT diagram) combined with advanced data mining in the
Virtual Observatory and identified ~300 candidates with MBH<2e5 Msun,
which pose as low-luminosity active galactic nuclei. The X-ray
detection would confirm their AGN nature and secure the IMBH
classification. We propose to observe 2 IMBH candidates with Chandra
as a pilot project: it will validate our search technique and allow us
to claim the discovery of the IMBH population

Sequence Number: 703468

Sequence Number: 401894

Title : The longest AMXP outburst: looking for pulsation in MAXI J0911-655
after 450 days
PI: Riggio
Abstract: MAXI J0911-655 (J0911) is a new rare accreting millisecond X-ray
pulsar (AMXPs), spinning at ~340 Hz in NGC 2808. Since the latest XMM
observation, the source has been monitored by Swift and INTEGRAL (ATel
#10425). Astonishingly, the source proved to be still in outburst
after more than 450 days. This is by far a record for an AMXP, whose
outburst usually last 2-3 weeks. Standing the current flux of the
source, we propose a 30 ks Chandra HRC-S timing mode DDT ToO aiming to
i) detect the pulsation, ii) obtain a precise spin frequency value to
obtain, for the first time, a direct measurement of the spin frequency
variation (expected to be ~1e-5Hz) during the same outburst, iii)
improve orbital parameters. Those information have strong scientific
return, because the presence of the pulsation will settle the still
debated model of the magnetic field burial under accretion, and the
measurement of nudot will permit to test the accretion mechanism and
the role in it of the magnetic field.

Sequence Number: 401893

Title : Testing a BeX origin for
PI: Maccarone
Abstract: We would like to extend the exposure time on Chakrabarty's TOO on this
source to 8 ksec. Our goal is to search for pulsations from the
source. It has a position consistent with a blue star with Galactic
reddening and an infrared excess in H band as seen by 2MASS. It also
shows a spectrum with Gamma=0.5+-0.5, which is typical for accreting
high-B field pulsars, but uncommon for low mass X-ray binary
transients. If confirmed, the source would be an X-ray pulsar at 25
kpc, which can be followed up optically. It gives us a start on
understanding the transient populations of the far side of the Galaxy
AND of the outer Galaxy. 8 ksec would allow for a 5 sigma detection of
the pulsation, even in the event of a fading by a factor of a few of
the source, and will give at least 5 cycles for any Be X-ray binary
pulse period.

Sequence Number: 502973

Title : X-rays as a probe of the progenitor of the Type Ia SN2017cbv
PI: Drout
Abstract: SN2017cbv is a nearby, bright, and young Type Ia SN that was recently
discovered in NGC 5643 (d~15 Mpc) within hours of explosion. Despite
their importance for Cosmology, questions still remain regarding the
nature and diversity of the progenitors that give rise to Type Ia SN.
Progress can be made by obtaining deep X-ray observations---which
probe the density of the CSM shaped by the progenitor system---for SN
which also have tight constraints on their final progenitor
configuration from early (1-2 day) optical/UV light curves. SN2017cbv
represents a rare opportunity when both sets of constraints are
possible. By timing X-ray observations with optical peak, we can probe
densities as low as a few d-9 Msun/yr, enabling us to distinguish
between many giant, main sequence, and double-degenerate progenitors.
SN2017cbv would represent only the third Type Ia SN for which such
deep limits are possible and this study may lead to the first
detection of X-ray radiation from a Type Ia SN.

Sequence Number: 401892

Title : Puzzling clump with 'whiskers' ejected from a binary
PI: Pavlov
Abstract: Three ACIS-I observations of 2011-2014 allowed us to discover an
extended object moving southwest from the famous high-mass gamma-ray
binary PSR B1259-63/LS 2883 with a surprisingly high velocity, ~0.06c,
perhaps even with acceleration. Such a phenomenon had never been
observed previously. We interpreted it as a clump of stellar matter
ejected from the disk around the massive star near binary periastron
and accelerated and illuminated by the unshocked pulsar wind. The
clump disappeared by 2015 Apr, but a new one was seen emerging from
the binary in 2016 Jan. The latest observation of 2017 Jan 6 showed
the new clump had moved southwest, but its morphology was very
unusual. Most notably, the elongated clump was crossed by narrow
"whiskers" perpendicular to the direction of motion. In addition, a
new extended feature was seen emerging northward from the binary. To
study the evolution of these unexpected features, we request a DDT
observation in April 2017.

Sequence Number: 703466

Title : M87 with Chandra and the Event Horizon Telescope
PI: Neilsen
Abstract: X-ray observations of accreting black holes are ideal for probing the
physical plasma processes close to the event horizon, which can
include both jet formation and magnetic reconnection leading to flares
and variability. Our ability to study these processes is about to take
a major step forward with the Event Horizon Telescope. During the
period April 5-April 14, the EHT will be online with ALMA and 7 other
stations around the world, and its observations of Sgr A* and M87 may
be the first set of observations capable of resolving the shadow of
these important supermassive black holes. But the ability to interpret
EHT data relies on a proper understanding of the plasma processes and
accretion structure around the black hole, as provided by Chandra. We
have arranged coordinated Sgr A* time; here we are requesting Chandra
time on M87 to probe variability and spectra of the accretion flow and
the jet knot HST-1.

Sequence Number: 703466

Sequence Number: 703465

Title : X-ray flux of the Narrow-Line Seyfert 1 galaxy WPVS 007 during a high
UV flux state
PI: Grupe
Abstract: We request a short, 10ks, observation with Chandra ACIS-S of the
highly X-ray variable Narrow Line Seyfert 1 Galaxy WPVS 007
quasi-simultaneously with HST between March 13 and 26. WPVS 007 is one
of the most unusual AGN showing strong variabilty in broad absorption
lines - a feature that is only seen in high-luminous quasars. We have
monitored WPVS 007 since October 2005 with Swift, but we can typically
not detect it in X-rays. Our last observation of WPVS 007 by Chandra
in March 2015 when it was fount to be in an extremely low UV flux
state (Leighgly et al. 2015) found it at a level of 8e-4 counts/s in
ACIS-s corresponding to a flux in the 0.3-10 keV band of 1e-17 W/m2.
Merging all Swift observaton since then (66ks) results in an 3sigma ul
of 1.4e-17 W/m2. Obtaining a Chandra observation close to the HST
observation will provide us with a crucial flux measurement that will
allow us to determine the intrinsic luminosity of the AGN. Note,
WPVS007 is currently at a bright UV state.

Sequence Number: 401891

Title : A Hig-Resolution Spectrum of the Black Hole GRS 1716-249
PI: Miller
Abstract: This black hole has been in outburst for several weeks, but it has
only recently become visible with the Swift/XRT and Chandra. The
strong outburst (0.2-0.3 Crab) has been visible with the BAT. On
January 27, we requested a Swift DDT of the source, and the resulting
spectrum is strongly encouraging. The source shows a strong, broad
iron line in just a 1 ks exposure, potentially with wind absorption
lines imprinted as well. We are currently attempting to expand the
number of black holes with spin measurements, and to better understand
the duty cycles of outflows. The XRT exposure gives a flux of 6 E-9
erg/cm2/s in the 0.7-10 keV band. Experience suggests that a 30 ks
HETG spectrum of a source at this flux level will yield a sensitive
Chandra spectrum. A spectrum has been sent to the Director.

Sequence Number: 100168

Title : Observing Jupiter's X-ray aurora during Juno apojove
PI: Jackman
Abstract: We don't know what causes Jupiter's auroral X-ray emission. Several
drivers (reconnection, Kelvin Helmholtz) have been suggested but all
require testing of local magnetic field and plasma to uniquely
constrain the source region of particles which cause the emission. The
Juno spacecraft at Jupiter has recently had a trajectory change and
will soon explore a previously unplanned region on the dawn flank near
the statistical position of the magnetopause boundary. We have
agreement to use in situ Juno data to complement X-ray observations.
We propose to observe during 3 apojoves, when Juno is furthest from
Jupiter. Depending on local solar wind conditions Juno will either
sample the solar wind, magnetosheath, or boundary layer inside the
magnetopause. Multiple observations will allow us to test X-ray
generation mechanisms under a range of external conditions. No other
mission of this type is planned in our lifetime and these orbits are
our only chance to sample this magnetospheric region.

Sequence Number: 100167

Sequence Number: 100166

Sequence Number: 502972

Title : iPTF17cw: A relativistic broad-lined type Ic supernova discovered by
iPTF
PI: Corsi
Abstract: Broad-lined supernovae of type Ic (BL-Ic SNe) are a rare form of
massive star core collapse. The link between BL-Ic SNe and gamma-ray
bursts (GRBs) was first made for GRB980425/SN1998bw, which showed
strong radio emission indicative of relativistic expansion. With SN
2009bb, we have learned that some BL-Ic SNe have relativistic ejecta,
but no associated gamma-rays. These "engine-driven" explosions are
extremely rare (one per 5-10 years), and represent the missing link
between ordinary (non-relativistic) BL-Ic SNe and GRBs. iPTF17cw is a
BL-Ic SN discovered by iPTF on 07 Jan 2017, while following-up LIGO
trigger G268556. Regardless of its association with the LIGO trigger,
our VLA radio observations show that this is a rare relativistic
(v~0.8c) BL-Ic SN. We ask for X-ray observations to constrain: (i)
emission mechanism (IC vs synchrotron) and (ii) synchrotron cooling
freq. (which, combined with radio observations, can constrain magnetic
field and ambient density).

Sequence Number: 703464

Title : Testing a new method for the identification of dual AGN
PI: Secrest
Abstract: Since most galaxies contain massive black holes, and mergers trigger
nuclear accretion, the hierarchical model of galaxy formation predicts
the existence of binary active galactic nuclei (AGN). Confirmed cases
of dual AGN are rare, with efforts for systematic identification
delivering a low yield of confirmed binaries. However, recent
observational and theoretical work has given a new clue in the hunt
for dual AGN: they may preferentially occur in galaxies with very red
mid-IR colors. We have cross-matched the WISE catalog with the 1300
galaxies in the SDSS MaNGA data release. We find a single galaxy with
sufficiently red WISE color (W1-W2=0.84) to classify it as an AGN. Not
only is the host galaxy clearly a spectacular late stage merger, but
the MaNGA IFU data show that the 2 stellar nuclei (separated by ~7
kpc) have optical emission lines consistent with AGN. However, X-ray
observations are required to confirm 2 separate AGN, rather than
extended radiation from a single source.

Sequence Number: 502971

Title : First Deep X-ray Observations of a Rapid, Luminous and Blue Stellar
Explosion
PI: MARGUTTI
Abstract: We propose the first deep X-ray observations of a rapidly-evolving,
luminous, blue stellar explosion. The new class of rapidly-evolving
luminous transients shows luminosities and time scales of evolution
that challenge the traditional Supernovae (SNe) models. Alternative
scenarios include a failed SN of a stripped star, the detonation of a
helium shell on a white dwarf and a SN shock breaking out from a dense
circumstellar medium. To date, due to their large distances (d>500
Mpc), rapidly evolving luminous transients have only been studied in
the optical/UV regime, which is of thermal origin and it is not
sensitive to the nature of the underlying energy source and properties
of the explosion's fastest ejecta. Here we propose to capitalize on
the unique opportunity to study a recently-discovered, nearby (d=150
Mpc), fast-evolving, luminous transient with Chandra to constrain the
environment and explosion properties of this new class of stellar
explosions for the first time.

Sequence Number: 502970

Sequence Number: 502969

Sequence Number: 300401

Title : An X-ray spectrum of a transient supersoft source in the Small
Magellanic Cloud
PI: Maccarone
Abstract: This is a transient supersoft source shown in ATel 9866, where we
found an unabsorbed flux of about 2e-11 in the SMC, with a temperature
of about 80 eV. This object was not in ROSAT, and was also observed by
Swift in response to an optical transient from ASSASN (ATel 9859). The
optical light curves clearly show no nova took place, but we now see a
new supersoft source. It is the first strong case for a supersoft
transient which is not a post-nova. How steady burning starts without
a nova is a mystery, but it may also be a key to understanding the
supersoft sources which are one of the proposed Type Ia supernova
channels. Understanding whether the system has emission lines, pure
continuum, or absorption lines, and which lines it has will determine
whether it really is a supersoft source. Exposure is based on trying
to detect the NVII absorption line at 24.78 Ang expected for a hot WD
(Rauch+ 2010). Tommy Nelson simulated and found a clear detection
requires 50 ksec.

Sequence Number: 401890

Title : Probing disk wind and other properties of 4U 1630-47
PI: Bhattacharyya
Abstract: The accreting Galactic black hole transient 4U 1630-47, which is
currently in outburst, is an ideal source to probe two types of
accreted matter ejection: (1) via disk wind and (2) via jet, both
using the observed narrow spectral lines (Diaz Trigo et al., 2013,
Nature, 504, 206; Neilsen et al. 2014; Diaz Trigo et al. 2014).
Chandra gratings are ideal to study such lines. The source also showed
indications of high-frequency (HF) quasi-periodic oscillations (QPOs)
in a rather high (150-450 Hz) frequency range, which can be extremely
useful to probe the strong gravity regime. The AstroSat satellite,
because of its large area and high timing resolution in a broad energy
band, can potentially detect and measure HF QPOs and probe the source
broadband spectrum and state. Hence, our proposed 30 ks Chandra
exposure, nearly contemporaneous with complementary AstroSat
observations, will provide an excellent way to probe the accretion and
ejection mechanism in the strong gravity regime.

Sequence Number: 401889

Title : Constraining the mass of an IMBH candidate in NGC 3310
PI: Earnshaw
Abstract: While much sought-after, intermediate-mass black holes (IMBHs) have so
far remained elusive. Ultraluminous X-ray sources (ULXs) are a good
place to look for IMBHs, and if one appears in the low/hard state we
would expect it to exhibit steady radio jets. A simultaneous
X-ray/radio observation of such an object would allow use of the
fundamental plane (e.g. Merloni et al., 2003) to measure its mass and
confirm its IMBH status. This method has been successfully used before
to identify NGC 2276-3c as a 5e4 solar mass IMBH in Mezcua et al.
(2015). We have found a radio source in NGC 3310 which coincides with
3 ULXs resolved by Chandra, none of which can be identified as the
X-ray counterpart using current radio data. We have been awarded
EVN/e-MERLIN time to attempt to detect and resolve the radio core,
therefore we request quasi-simultaneous observations of this source to
match the radio source with an X-ray source and provide the X-ray
luminosity from which we can calculate the BH mass.

Sequence Number: 201154

Title : Proxima Cen's Stellar Cycle
PI: Wargelin
Abstract: Based on 15 years of optical monitoring, 4 years of Swift X-ray/UV
data, and 2 HRC observations we find evidence for a 7-yr stellar cycle
in Proxima Cen (dMe5.5), a fully convective star. A stellar cycle is
very exciting because most models of stellar magnetic activity predict
such stars cannot support solar-like cycles. Understanding the
structure and evolution of Proxima's magnetic field is also important
because that's what drives X-ray/UV emission and the stellar wind,
which are important factors in modeling the atmosphere (atmospheric
stripping) and habitability of its newly discovered exoplanet. And as
noted by the discovery announcement, "The robust detection of Proxima
b has only been possible after reaching a detailed understanding of
how the star changes on timescales from minutes to a decade." Further
X-ray measurements are required now, while the cycle appears to be at
a maximum, for confirmaton and to better characterize Proxima's
activity over time.

Sequence Number: 201153

Sequence Number: 201152

Sequence Number: 201151

Sequence Number: 401888

Title : Chandra Spectroscopy of SMC X-3 in Outburst
PI: Coe
Abstract: SMC X-3 is an HMXB and pulsar in the SMC. It is currently in the midst
of an apparently super-Eddington outburst (10^39 erg/s, or about 10x
Eddington for a neutron star). This is the brightest outburst from
50-60 sources traced by Coe et al. over a decade, and a special
opportunity. The predicted HETGS count rates will give sensitive
spectra. Lines from the massive companion wind are anticipated; if the
source is truly super-Eddington very strong outflows should also be
detected since radiation and gas will be strongly coupled. Simulated
40 ks spectra based on recent XRT observations, including plasma
components, predict 3-5 sigma line detections in the HETGS band.
Stronger detections are expected if a super-Eddington outflow is
present. Recent work on ULXs shows that at least one such source is a
super-Eddington neutron star. SMC X-3 is much closer and may offer
insights into the accretion flow geometry and physical processes in
this rare accretion phase.

Sequence Number: 401888

Sequence Number: 401881

Title : Revealing the nature of the mysterious new SMC Transient: Swift
J003233.6-7306
PI: Kennea
Abstract: Starting June 8th, 2016, the Swift SMC Survey, AKA S-CUBED (Kennea et
al., ATEL #9299), began a weekly shallow X-ray survey of the SMC to
search for >1% L_Edd X-ray transients. We have discovered a new
puzzling X-ray transient Swift J003233.6-7306, on the western edge of
the SMC. A NuSTAR DDT observation revealed a hard X-ray spectrum
(Gamma = 1.7), canonical for a BH LMXB in the low/hard state, or
possibly Be/X-ray binary (common in the SMC). The Swift position is
not consistent with any optical counterpart, which is puzzling if a
binary, however given the error in the position from Swift (~4") we
cannot rule out nearby stars as the counterpart. We request a short
(1ks) Chandra in order to localize this transient to the at least ~1"
accuracy needed to definitively identify any counterpart in deep
optical data obtained on the field by OGLE. A firm detection or
non-detection in optical, given the low absorption towards the source,
would place strong constraints on the object type.

Sequence Number: 502963

Title : Prompt Chandra observations of PSR J1119-6127 and its compact nebula
following its magnetar-like burst
PI: Blumer
Abstract: PSR J1119-6127 is a high-magnetic (B) field pulsar with spin
properties (P=408 ms, age=1.7 kyr, B=4.1e13 G) similar to those of
J1846-0258, the first high-B pulsar to show magnetar-like behavior and
one of a handful for which a braking index has been measured
(n=2.91+/-0.05). Chandra studies of J1119-6127 allowed the first
detection of the X-ray counterpart and revealed the evidence for a
compact and faint pulsar wind nebula (PWN; Gonzalez & Safi-Harb 2003
ApJ, 591, 143). A follow up study found evidence for an elongated jet
to the south, and resolved the PSR spectrum from its compact PWN
spectrum for the first time (Safi-Harb & Kumar, 2008, ApJ, 684, 532).
J1119-6127 is considered as a key source in our understanding of the
physical characteristics and processes that differentiate radio
pulsars from magnetars. Just like J1846-0258 , it was predicted that
J1119-6127 will one day reveal itself as a magnetar after an
occasional burst driven by its high B-field.

Sequence Number: 300392

Title : Down with the King: FO Aqr in an Extended Low State
PI: Kennedy
Abstract: FO Aquarii, the so called king of the intermediate polars, is in an
unprecedented and prolonged faint state. Normally brighter than V =
14, FO Aqr is currently at V ~15 and was as faint as V~15.7 at the
start of 2016 May. The faint state began at unknown time between 2015
Dec. 18 (V = 13.71, S. Dvorak, AAVSO) and 2016 May 6 (V ~ 15.6, our
measurement). (For more, including the long term light curve, see
http://www.astronomerstelegram.org/?read=9216) Recent optical
observations have also shown the pulsations to now have a period of
around 11.1 mins (http://www3.nd.edu/~clittlef/FOaqr.png), suggesting
the 2 accretion poles are currently visible. This may be due to a
change in the accretion geometry. We wish to investigate changes to
the x-ray flux and spectrum, and whether the x-ray spin period, which
was seen to be 20.9 mins by Evans et al. (2004, MNRAS, 349, 715) using
XMM-Newton, has also changed to the 10 mins seen in the new optical
data.

Sequence Number: 401819

Title : Measuring the spin period of XMMU J004855.5-734946 during a large
outburst
PI: Vasilopoulos
Abstract: Spin periods of Be/X-ray binary (BeXRB) pulsars are important for
probing their formation channels and the connection between orbital
period and pulsar spin in XRBs (Knigge+ 2011). From the 120 BeXRBs in
the SMC only 50% have known spin periods, with the majority of them
measured during outburst with ToOs. From the remaining systems only 6
have a known orbital period. XMMU J004855.5-734946 is a BeXRB in the
SMC (Haberl & Sturm 2016, XMM Lx ~(0.03-1)x10^35 erg/s) with a 36.43d
orbital period (Atel#9198), but with no X-ray pulsations detected so
far. On 06/24 a 37s Swift/XRT observation detected the system at
Lx~10^37 erg/s (Atel#9197) following a marginal detection on 06/16
(Lx<5x10^36 erg/s) confirming the onset of a large outburst. A
follow-up 1ks Swift ToO on 06/29 measures an Lx = 8.3x10^36 erg/s.
This is a unique opportunity to measure the spin period of one of the
few BeXRBs in the SMC with known orbital period but unknown spin
period.

Sequence Number: 502667

Title : SGR 1935+2154 in a very active state
PI: Kouveliotou
Abstract: The magnetar SGR 1935+2154 has been active since the middle of May
2016 emitting several bursts per day that have triggered the
Fermi/GBM. The burst intensities have been gradually increasing and on
June 26, 2016 the source emitted a very bright burst indicating
potential extreme further source activity. The source persistent
emission properties are strongly influenced by such activity, both in
timing and spectra. We request a Chandra DDT observation to study the
change of the persistent source properties, and potentially study
similar properties for serendipitously recorded bursts. In particular,
we note that the currently reported Nh (GCN 15590) its 3 times higher
than the one measured in the past (Israel etal. 2016) which leads us
to believe that the recent burst is accompanied with metal enhanced
outflow.

Sequence Number: 502666

Title : Chandra Observations of the Brightest and Closest H-poor Superluminous
Supernova Gaia16apd
PI: Yan
Abstract: Gaia16apd was first triggered as a 17.3 mag transient (now 16.5mag) on
2016-05-16 by GAIA. The first optical spectrum on 2016-05-20.92 UT
classified it as a H-poor superluminous supernova (SLSN-I) at z=0.102
and absolute magnitude of -21.0 (Atel #9071). This makes Gaia16apd one
of the brightest and the closest SLSNe-I. SWIFT observations on
2016-05-21 revealed an extremely UV bright source, 15.3mag at 2310A.
Gaia16apd has similar apparent brightness as ASASN-15lh, the most
luminous SLSN-I ever discovered. ASASN-15lh has been observed by
Chandra, and was reported with detections. Magnetar models (Metzger et
al. 2014,Fig.12) predicted that SLSNe-I should have X-ray emission
post optical-peak. With the predicted fluxes well within the Chandra
limit in 10ksec, Gaia16apd offers the unique opportunity to constrain
theoretical models. The proposed observation will shed light on the
long standing mystery of what powers the luminous optical emission
from SLSN-I.

Sequence Number: 502665

Sequence Number: 502664

Title : An outburst of the CCO 1E161348-5055: an accreting neutron star or a
peculiar binary magnetar?
PI: Rea
Abstract: The INS 1E161348-5055 is a Central Compact Object (CCOs) in the center
of the 2kr young SNR RCW103. It has been an intriguing source all
along. Several hypothesis about the nature of 1E1613 have been
proposed as a binary neutron star system, a very slow magnetar or even
a CV (see Pizzolato et al. 2008). The bright thermal X-ray emission of
other CCOs, and the low dipolar B field (~10^11 G), have been
interpreted as evidence of "hidden" strong magnetic fields within the
CCO crusts, burried by accretion. 1E1613 was instead considered an
outlier because of the lack of pulsation, but the presence of a
peculiar 6.4hr periodicity. Our undergoing Swift monitoring of 1E16134
show the source at a flux of a factor of 10 higher, and with a harder
spectrum (PL ~1.7) than usual (see figure in the link). Furthermore,
apparently Swift BAT detected a "possible"burst from this direction
(GCN 19547/GRB 160622A), although its association with the CCO is
still unclear (if any).

Sequence Number: 502663

Title : Understanding the Mass-Loss History of the Progenitors of Type IIn
Supernovae: SN 2016bkv
PI: Patnaude
Abstract: The mass-loss history of massive stars is one of the least understood
and yet fundamental aspects of stellar evolution. HOW and WHEN do
massive stars shed their massive envelopes? Is there a relationship
between the expulsion of the stellar envelope and core-collapse? These
central, yet open questions motivate the present investigation. In
regards to these questions, studying the evolution of a supernova
shock as it interacts with the ejected envelope of the progenitor
provides insight into how much mass was lost and perhaps most
importantly, when it was lost relative to core-collapse. X-ray
emission from the shocked gas probes the dynamics of the interaction
and, when combined with other ongoing and planned multi-wavelength
observations, serves to constrain properties of the surrounding
circumstellar gas and the end-stages of the progenitor's evolution. We
propose to study SN2016bkv in order to understand the final mass-loss
phase prior to the core-collapse of its progenitor.

Sequence Number: 401818

Title : An exceptionally cold neutron star in HETE J1900.1-2455
PI: Degenaar
Abstract: The ~1 km thick crust of neutron stars is strongly heated by nuclear
reactions during accretion outbursts, but cools in quiescence. HETE
J1900.1-2455 continously accreted since 2005, but in 2015 late Oct its
intensity dropped below the detection limit of MAXI. Swift
observations (Mar 7) fail to detect the source, implying Lx (0.5-10 keV) and a very cold neutron star crust of kT<65 eV. This is
highly unexpected, as the crust should have been significantly heated
during the ~9 yr outburst: our studies of 5 other sources after >1 yr
outbursts revealed hot neutron star crusts of >100 eV. This remarkable
result suggests that nuclear heating may not always be efficient, a
scenario that has never been considered to explain exceptionally cold
neutron stars such as SAX J1808.4-3658 and 1H1905+000. With a 30 ks
DDT, we can put firm constraints on the crust temperature in HETE
J1900 (kT~33 eV; Lx~2e30 erg/s), with important implications for
neutron star heating/cooling models.

Sequence Number: 703301

Title : Detecting an X-ray Counterpart to an Active TeV Flaring Event in the
M87 Jet
PI: Cheung
Abstract: M87 is currently in an active TeV flaring state with 7% Crab detection
March 7 (4.1 sigma; VERITAS), confirmed at 8% Crab on March 8 (3.6
sigma; MAGIC) satisfying threshold for triggering monitoring with all
three TeV telescopes. Previous TeV high-states lasted 1-2 week saw
day-scale flares at >3x the ~2% Crab quiescent flux. TeV flaring was
seen thrice previously since regular monitoring began in 2004. Sparse
1-2 week interval Chandra coverage in 2005 & 2008 gave ambiguous
results. In 2010 the first of 5 daily Chandra ToO exposures was
obtained in just <3 days from our trigger but the TeV flare subsided.
Thus the first Chandra observation in Mar 2016 should commence asap in
order to isolate TeV emission site in M87 via correlated variability
while in high TeV state. M87 nucleus and 0.8" offset jet knot HST-1
are known X-ray variable and Chandra can separate their
contributions.

Sequence Number: 703300

Sequence Number: 703299

Sequence Number: 703298

Sequence Number: 703297

Sequence Number: 703296

Title : Image D Of Huchra's Lensed Quasar: Waiting For The Other Shoe To Drop
PI: Pooley
Abstract: In mid-2013, image D of Huchra's Lens began fading precipitously in
the optical (as seen by OGLE). One expects corresponding brightness
changes in X-rays, as the X-ray region is thought to be smaller, by a
factor of 4, than the optical continuum region (Mosquera et al), but
with the changes occurring more rapidly. At the start of the 2014 OGLE
season (MJD 56826), image D was 0.7 mag fainter than in mid-2013. Our
analysis of archival Chandra data shows that there was no X-ray drop
on MJD 56815 compared to Chandra data from mid- to late-2013. This is
somewhat surprising, and it would be even more surprising if image D
were still as bright as on MJD 56815, given the continuing decline in
the optical (during 2015, image D had fallen ~2 mag below its mid-2013
level); this would (uncomfortably) imply that the X-rays and optical
come from separate non-concentric regions. We request a 30 ks
observation of 2237+0305 to determine whether image D has also fallen
by a factor of ~6 in X-rays.

Sequence Number: 502662

Title : SN2005ip awakens: an unprecedented glimpse of explosive mass-loss
10,000 years before core-collapse
PI: Mauerhan
Abstract: SNe interacting with circumstellar material (CSM) have raised critical
questions about the latest phases of massive-star evolution. SN 2005ip
is a case where >15 MSun of CSM was ejected by the luminous blue
variable (LBV) progenitor several years before core collapse,
reminiscent of Eta Car's historic eruption. So far we have no
explanation for the cause of pre-SN eruptions; potential factors
include late nuclear burning stages, or violent binary encounters.
After a decade of steadily fading interaction with stellar wind,
SN2005ip began interacting strongly this month with a distant dense
structure of CSM ejected 10,000 yr before the SN, providing an
unprecedentedly distant look-back time on the progenitor's pre-SN
mass-loss history. The CSM could have an origin similar to the ring
around SN1987A, also launched 10,000 yr before SN. We request DDT
ACIS-S observations of 2005ip before it fades, to measure the
interaction energy and mass of the CSM, in order to elucidate its
origin.

Sequence Number: 300391

Title : The accretion disk of a rare jet-driving symbiotic binary during its
brightest outburst in a ~century
PI: Lucy
Abstract: The current optical outburst (ATel#8653) of the symbiotic star
(interacting white dwarf [WD] + red giant) MWC 560, its brightest in
>87 years, provides a rare opportunity to examine the physics of jet
production in the otherwise well-understood context of WD accretion.
This proposal's goal is to use X-ray emission from the accretion-disk
boundary layer to characterize changes in the disk associated with
strong jet production/acceleration. MWC 560 drives a jet, and optical
spectra taken over 2 months during the peak of the last outburst, 26
years ago, showed Balmer absorption velocities increasing from 3000
km/s to their record velocity of 6000 km/s (Tomov et al. 1990).
300-2800 km/s Balmer troughs have just been observed, suggesting the
early phase of jet acceleration. Chandra will reveal whether the
jet-driving disk remains intact and brightens in X-rays (we expect the
boundary layer to remain optically thin) or the degree to which the
inner disk is evacuated (as in X-ray binaries).

Sequence Number: 300391

Sequence Number: 703295

Title : Catching a Changing Look Quasar as it retreats to the Shadows for the
Second Time
PI: Tremblay
Abstract: We propose an urgent, exciting, and short (30 ksec) Chandra DDT
observation of Mrk 1018, enabling a first-ever observation of a quasar
returning to an obscured Type 2 (narrow-lined) state *for the second
time*. In 1986, the source was identified as one of the first-known
``changing look" quasars, transitioning from a Seyfert 1.9 to a
Seyfert 1 nucleus. This extreme variability was due either to dramatic
intermittency in the accretion rate, or because an eclipsing cloud
vacated our line of sight, revealing the broad line region. Last week,
in examining our new VLT/MUSE IFU data for this source (obtained as
part of the CARS survey, www.cars-survey.org), we were astonished to
discover that the source has just now reverted *back* to a
narrow-lined Seyfert 1.9. Optical photometry shows that the AGN has
dimmed by an entire magnitude over the past year, and shows no signs
of slowing. Chandra is urgently needed to directly test both
hypotheses (i.e., cloud passage vs. accretion rate change).

Sequence Number: 401817

Title : Confirming X-ray brightening of the PSR J2032+4127 binary system
PI: Ho
Abstract: We propose a 5 ks observation of the radio and gamma-ray pulsar PSR
J2032+4127 and its binary (Be-star) companion MT91-213. Even though
there are many known Be-neutron star binaries, this system is unique
in many ways, including its very long and eccentric orbit, proximity
(1.4 kpc), and careful radio monitoring and timing. Neutron stars in
these types of binaries usually undergo luminous X-ray outbursts
during periastron, as they accrete matter from their Be-star
companion. PSR J2032+4127 will reach periastron in early 2018, and the
anticipated X-ray outburst (and radio monitoring) will provide
important insights into the accretion process and physics of neutron
stars and their magnetic fields. Our proposed short observation is
needed in order to produce a baseline for the upcoming outburst,
especially with several other nearby X-ray bright sources.

Sequence Number: 502661

Title : The Young Type IIP Supernova ASASSN-16at
PI: Grupe
Abstract: We propose to observe a young (~5-day old), nearby (16 Mpc) type IIP
supernova ASASSN-16at with Chandra for 5ks. We tentatively detect the
supernova with Swift XRT. Chandra had observed the field in November
2005, but no X-ray source was found, strengthening the possibility
that the Swift detections are associated with the supernova. However,
precise Chandra astrometry is needed to establish the association.
Detections of SNe IIP this early are rare - only 3 have been detected
in X-rays within the first 10 days. Such very early phase X-ray
detection can put important constraint on its immediate circumstellar
exploding environment, which can subsequently probe the mass loss mode
of the RSG progenitor within a decade before the explosion.
Furthermore, the tentative Swift detection places ASASSN-16at among
the most luminous SNe IIP in X-ray, and the Chandra measurement will
test the recently proposed upper limit on the RSG progenitor mass loss
rate for this class of supernovae.

Sequence Number: 201084

Title : X-ray irradiation and evaporation of a likely ocean planet
PI: Wheatley
Abstract: The super-Earth transiting the bright K star HD97658 (V=7.7) has a
density impling a bulk composition dominated by water. X-ray/EUV
irradiation of the planet is expected to photodissociate the water
envelope and drive a hydrogen-rich wind that should be detectable at
Lyman-alpha with HST/STIS. We have HST transit observations scheduled
for Dec and Jan that are designed to detect the escaping hydrogen and
establish the presence of a water reservoir on HD97658b. This would be
the first signature of an evaporating ocean on an exoplanet. Here we
request Chandra observations to measure the mean X-ray flux of the
star in the hours preceding the two HST observations. This will allow
us to determine the energetic efficiency of atmospheric escape in the
case of detected absorption, or to place limits on the abundance of
water in the absence of absorption. Chandra coverage of both transits
will allow us to interpret variability in water loss in the context of
the changing radiation environment.

Sequence Number: 201084

Sequence Number: 502660

Title : Search for an X-ray counterpart from a repeating Fast Radio Burst
PI: Scholz
Abstract: Fast radio bursts (FRBs) are a new class of ms bursts discovered using
the Parkes radio telescope (Thornton et al. 2013). FRBs appear to be
one-off events with very large dispersion measures (DM) that suggest
cosmological distances, but unknown origins. Last year, we discovered
the first non-Parkes FRB 121102, DM=557 pc cm^-3, 3x the predicted
Galactic column (Spitler et al. 2014). Remarkably, we detected ~10
more bright radio bursts in Arecibo data from June at the same DM. We
have just detected another burst on Nov 13th using GBT. The June
bursts suggest a period of 8s. This period is typical of magnetars.
This thus could be an extra-Galactic magnetar, and may solve the FRB
mystery. This sky position has yet to be observed by any X-ray
telescope other than ROSAT whose response is too soft to be useful. We
request Chandra DDT time to search for an X-ray counterpart which
would test the magnetar hypothesis and, crucially, localize the
source, thus enabling an ID of a galaxy host.

Sequence Number: 401816

Title : High Spatial/Temporal Resolution Chandra Follow-up of the 2015
outburst of the X-ray pulsar SMC X-2
PI: Li
Abstract: Accretion and propeller are the major processes driving the pulsar
evolution. SMC X-2, a 2.37s X-ray pulsar (Corbet+ 2000), is one of a
few important examples showing strong accretion outbursts and low
accretion propeller quiescences, occasionally. 2 close (2") possible
optical counterparts, a variable brighter Oe and a stable fainter Be,
have been reported (Schmidtke+ 2006). In 2015 Sep, Swift/BAT and
MAXI/GSC independently detected an outburst at 15 mCrab. A rapid XRT
ToO confirms the result with the best ever accurate localization at
<3.6". But still, depending on how the XRT astrometry is done, both
the reported counterparts can be real. While our analysis on the most
recent XRT data (WT) tentatively shows the spin period is by 0.001s
faster than the one detected by RXTE/ASCA in 2000, a more sensitive
data is required to confirm this. We thus request a 2.8ks timing mode
HRC-S observation to 1) determine the optical companion and 2) verify
spin-up history over the last 15 years.

Sequence Number: 703280

Title : Simultaneous Chandra and NuSTAR Observations of the Highly Obscured
AGN Candidate in NGC660.
PI: Annuar
Abstract: We are using NuSTAR to undertake a detailed investigation of the
obscured AGN population at D<15Mpc. Our latest target is NGC660 where
the presence of an AGN has been ambiguous. However, recently it was
observed to undergo a radio outburst which reveals a bright continuum
source (Argo et al. 2015), coincident with Chandra 2-8 keV emission
from one of the three point sources near the nucleus (<5"). This
confirms and pinpoints the X-ray position of the AGN. Comparisons of
the Chandra flux with the radio emission and other multiwavelength
luminosity indicators indicate that the X-ray flux is suppressed,
suggesting that it is absorbed by a high column of gas. A NuSTAR
observation for this object has been scheduled as part of our program.
The requested Chandra observation is essential to unambiguously
constrain the AGN and isolate it from other sources at <8 keV. When
combined with NuSTAR, we will then be able to accurately characterise
the 0.5-30 keV spectrum of the AGN for the first time.

Sequence Number: 100155

Title : Chandra Observations of Pluto's Escaping Atmosphere in Support of the
New Horizons Encounter with Pluto
PI: McNutt
Abstract: Current models of Pluto s extended atmosphere remain uncertain.
Applying knowledge gained from studying cometary X-ray emission,
Chandra ACIS-S photometric imaging of X-rays produced by CXE between
the solar wind and Pluto s atmosphere addresses both the atmospheric
density and the interaction of the solar wind with the extended
Plutonian atmosphere. An exploratory measurement on 24 February 2014
for 35 ksec provided a marginal X-ray emission signal from Pluto given
the low solar wind flux at the time. By increasing the observing time
by a factor of 4 (to 140 ksec), the tentative Cycle 15 detection will
be verified or much tighter upper limits on the neutral gas escape
rate will be determined. The timing of the observation is fixed in
time to coincide with the encounter of the New Horizons (NH)
spacecraft with Pluto, a unique in situ event in solar system
exploration. Chandra provides a unique, global and contemporaneous
X-ray measurement of the system.

Sequence Number: 100155

Sequence Number: 401698

Title : Light Echoes from V404 Cyg
PI: Heinz
Abstract: In June 2013, V404 Cyg went into a bright outburst after 26 years of
quiescence. The source flux is now in decline. Swift observations
reveal the presence of four bright rings, caused by scattering off of
interstellar dust clouds between us and the source. This is only the
third fully resolved echo of a Galactic source. Because the distance
to the source is accurately known, it is possible to perform precision
dust tomography and calibrate the use of dust echoes as distance
measure. To reach the required sensitivity, avoid cross contamination
with dispersed spectra of the dust scattering halo, and be able to
accurately model and remove cosmic and particle backgrounds, gratings
observations cannot be used for this science, and we ask for a 30ksec
full frame imaging observation.

Sequence Number: 100155

Sequence Number: 401697

Title : The Next Step for V404 Cyg
PI: Neilsen
Abstract: In May 1989, the black hole V404 Cyg exhibited some of the brightest,
most dramatic variability ever seen from a Galactic X-ray binary. The
spectacular variability, lasting only 1-2 weeks, was followed by a
slow 6 month decay. Given the extremity of the outburst and the
significant deviations from canonical BH behavior, little is
understood about the physics of this remarkable system. A new outburst
began on June 16, but how closely will V404 Cyg follow the BH track
after its initial fireworks have ended? P Cygni profiles are seen in
the optical (ATel 7669). Will V404 Cyg produce a massive X-ray disk
wind? A strong variable iron line has also been reported (ATel #7694).
We propose two 40 ks observations (~2 orbital periods), in 20-30 and
40-60 days, to study the variable Fe line and search for X-ray
absorption diagnostics of the growing wind during the later portions
of the outburst. Even on our time scale, we expect fluxes near 0.25-1
Crab and a factor of ~5 variability.

Sequence Number: 401696

Title : Detecing Super-Eddington Driven Winds in V404 Cyg
PI: King
Abstract: V404 Cyg has gone into outburst(ATEL 7646..7663). The light curve from
its last (1989) outburst was characterized by a dramatic rise starting
May 23 until May 30, where it then plummeted in X-ray flux (Zycki99),
unusual for X-ray binaries. The outburst was also very close to its
Eddington limit (Tanaka89, Zycki99). Super-Eddington accretion can
explain the bizarre light curve behavior, as ejection of accreting
shells driven by radiation pressure may have disrupted the disk and
caused the dramatic decrease in flux. V404 is now in outburst, and we
will examine its behavior with unprecedented spectral resolution with
the Chandra HETG.Based on our previous work with J17091-3624 (King14),
GRO 1655-40 (Miller08), and GRS 1915+105 (Miller in prep), we find
that 40 ksec is sufficient at detecting lines at >3 sigma. Finding
evidence for winds (or lack there of) will have vital implications for
outflow generation during Eddington accretion phases, feedback, and
growth of black holes.

Sequence Number: 401695

Sequence Number: 401694

Title : The brightening of M82: The intermediate mass black hole or ultra
luminous X-ray pulsar?
PI: Brightman
Abstract: Swift XRT monitoring of M82 has shown that the X-ray emission from the
galaxy has increased by a factor of ~4 from its usual 2-10 keV
luminosity of 1x10^40 ergs/s. Previous flux increases have been
attributed to the intermediate mass black hole candidate, X-1,
entering the thermal disk-dominated state (Feng & Kaaret 2010),
however the neighboring source, X-2, recently identified as an ultra
luminous pulsar (Bachetti et al 2014) has also been known to reach
10^40 ergs/s. At 4 arcsec separation, only Chandra can tell which
source is causing the current brightening. With an off-axis
observation with a sub array of pixels to mitigate pile-up, valuable
spectral constraints will be provided by Chandra. Furthermore, if this
Chandra observation is approved, we will trigger a NuSTAR ToO to
measure the high energy spectrum of the source, whichever it may be.

Sequence Number: 502493

Title : Mapping the evolution of SNhunt275 to shed light onto the last
evolutionary stages of Massive Stars
PI: MARGUTTI
Abstract: The mass-loss history of massive stars is one of the least understood
and yet fundamental aspects of stellar evolution. HOW and WHEN do
massive stars lose their hydrogen envelopes? This central, yet
still-open question motivates our investigation. Here we ask for
Chandra observations to map the evolution of the transient SNhunt275
on its way to become a Supernova. SNhunt275 was identified in 2013 as
a luminous outburst from a stellar object in NGC2770. The same star
gave rise to a luminous display earlier this year and recently
underwent a drastic re-brightening and spectral evolution which likely
prelude to a major explosion, in close similarity to SN2009ip. Our
primary goal is to constrain the density and location of the material
in the immediate environment of SNhunt275, and hence the mass-loss
history of its stellar progenitor over the last ~100 yrs. This is only
possible through deep X-ray observations that sample the emission
arising from the shock interaction with the medium.

Sequence Number: 502492

Sequence Number: 401693

Title : Snapshot observations of 2S1553-542: determination of the source
nature
PI: Lutovinov
Abstract: We propose to perform a snapshot observation of the transient source
2S1553-542, which demonstrated an outburst last three months. The
current outburst is a third one only detected from this source since
1975 (the second one was in 2007). Previously the source nature was
tentatively proposed as a X-ray pulsar (pulse period 9.3 sec) in the
Be binary system due to the outbursts activity. But no optical
counterpart was established till the moment. One of main reasons of
this is a lack of knowledge of exact coordinates of the source. The
proposed observations at the outburst decay stage is a unique chance
to determine the source coordinates with a high precision, to perform
follow-up observations in optical and infrared wavebands and establish
its nature. Additionally, based on the results of spectral analysis we
will determine if the source is still accreting at low level or we
observe the heated neutron star.

Sequence Number: 401692

Title : The Structure of the Accretion Flow in SAX J1808.4-3658 at Low
Luminosities.
PI: Patruno
Abstract: The accreting pulsar (AMXP) SAX J1808.4-4658 is now in outburst (ATel
#7346). Seven more have been observed, with pulsations at 401 Hz.
Recently, we made two key discoveries: i. the accretion disk of SAX
J1808 might be truncated close to the co-rotation radius (i.e., where
plasma co-rotates with the neutron star) even at the lowest
luminosities (1e33 erg/s). We suspect that this is due to a new type
of accretion flow: the "trapped dead disk" (see
Patruno+2015,arXiv:1504.05048). ii. we have phase-connected *all*
pulsations observed by RXTE (Patruno+, in prep.), having now a 13 year
baseline. This is unprecedented for any AMXP. If we phase connect *one
more outburst* we can constrain the proper motion and variations of
the semi-major axis for the fisrt time. We'd like to find pulsations
at low luminosities (during reflares) and conclusively determine
whether a disk extends down the co-rotation radius. Then phase connect
these pulsations with our previous 13-yr baseline.

Sequence Number: 502491

Title : Search for a Jet Break in the Short GRB 150423A
PI: Berger
Abstract: Understanding the collimation of short GRB jets is critical for
inferring their true energy release and event rate. This not only
impacts our understanding of these explosive events (e.g. energy
extraction and dissipation), but given their likely association to
neutron star binary mergers also feeds into the expected Advanced LIGO
merger rate, and the expected brightness of Advanced LIGO
electromagnetic counterparts. At the present only 4 short GRB jet
opening angle measurements have been made (by our group using Chandra
and XMM), so every additional measurement will have an impact on the
opening angle distribution. Here we request a single 25 ksec Chandra
observation on a timescale of about 7 days post-burst to measure the
decline rate relative to the XRT early data and hence to determine the
jet opening angle. The detection of a break will indicate a jet of
5-10 deg, while a non-detection will point to a broad outflow with >10
deg.

Sequence Number: 401691

Title : Seizing a rare opportunity to catch a disk wind in a neutron star
X-ray binary
PI: Degenaar
Abstract: In low-mass X-ray binaries (LMXBs) a neutron star or a black hole
accretes matter from a low-mass companion star via an accretion disk.
Outflows in the form of X-ray disk winds and radio jets are
universally linked to the accretion process. During low-luminosity
(<1E37 erg/s) "hard" X-ray states radio jets prevail, whereas disk
winds are only seen during high-luminosity (>1E37 erg/s) "soft"
states. Disk winds are now routinely detected and studied in black
hole LMXBs, but much less is known about such winds in neutron star
LMXBs, which are often fainter. Here we propose to seize the rare
opportunity to study the disk wind in a transient neutron star LMXB,
which is currently exhibiting an outburst and entered an X-ray bright
soft state on April 4th. Swift/XRT observations reveal ionized
absorption features at high (>5 keV) energies that are indicative of a
disk wind in this system. Only with the unprecedented spectral
resolution of Chandra/HETG can these features studied in detail.

Sequence Number: 300338

Title : GK Persei in the current dwarf-nova-like outburst
PI: Orio
Abstract: GK Persei is the "all-in-one" white dwarf interacting binary. It can
be classified as a nova (outburst in 1901), as a symbiotic because of
the red giant companion, as a magnetic system (it is an intermediate
polar or IP), as a dwarf nova (every ~2 years it has repeated
disk-instability-related outbursts) and even as a "mini-supernova
remnant" (it has just "made the news" again, with a Chandra
press-release, because of its luminous at-all-wavelengths, and still
expanding shell ejected in 1901). In March a new dwarf- nova-like
outburst started and we have been monitoring it with Swift. The count
rate in the Swift XRT varies between about 1 and about 2 cts/s (ATels
7246, 7248) and the Swift spectrum indicates a main component of the
X-ray flux, a thermal one, that peaks at energy well above the Swift
range - for this reason we have applied also for NuSTAR time. However,
only grating spectra reveal the full physical picture: we plan to
study how GK Per is evolving.

Sequence Number: 201026

Title : The dim state of RW Aur
PI: Schneider
Abstract: In Oct 2014 the well studied young star RW Aur A was unexpectedly
obscured by the tidally disrupted disk of its close but resolved
binary companion RW Aur B (Petrov et al. 2015,
arxiv.org/abs/1503.04158). Such events are extremely rare and provide
us with a chance to directly measure the gas-to-dust ratio of
protoplanetary disk material. We can measure this ratio by comparing
the differences in X-ray absorption (caused by gas) and optical
absorption (caused by dust) before and during the obscuration event.
So far, estimates are highly model dependent; this observation offers
an actual measurement to tightly constrain planet formation models
that currently suffer from our ignorance of reliable disk gas masses.
Such dimming events are short (the only known other such event lasted
180 days) and unpredictable and thus require quick follow-up
observations when seen in a key system such as RW Aur, where the
bright state is already well characterized at optical and X-ray
wavelengths.

Sequence Number: 502490

Title : Calibration of the ACIS GRADED mode using the Cas A CCO
PI: Posselt
Abstract: The potential temperature (T) decline of the Central Compact Object
(CCO) in the Cas A SNR is important to probe fundamental physics via
the study of neutron star cooling. An exciting T-decline found from
GRADED(G)-mode observations is called into doubt by results from
subarray FAINT (F) observations. Possible reasons are pile-up and
grade migration in the G-mode. Cross-calibration of the different
instrument setups was not possible previously due the poorly known
spatial distribution of the filter contaminant. We propose a
calibration subarray F observation of Cas A with the CCO centered at
exactly the same chip position as in a contemporaneous G-mode
observation. This will allow us to obtain a contaminant-independent
assessment of the G-mode effects on the CCO spectrum. With this, one
can re-calibrate the past 19 G-mode data sets. Such a
cross-calibration will be also useful to the general X-ray community.

Sequence Number: 401690

Title : Chandra Observation of 'GRB 150301C' / [PFH2005] 622
PI: Burrows
Abstract: On March 1, 2015, Swift responded to a strong hard X-ray flare (1000
cps) in the direction of M31, lasting 20 s. It was initially
classified as a possible GRB and given the name GRB 150301C. The lack
of a soft X-ray counterpart was very puzzling. Further analysis showed
a very weak counterpart at about 100 s after the trigger, but this
faded rapidly. The only sources similar in terms of BAT to XRT flux
ratio are short GRBs and SGR flares, both of which are much shorter in
the duration of the hard X-ray burst than this object. XRT found a
single very faint, but fading, object within the BAT error circle,
coincident with a known X-ray source found in an XMM survey of M31:
[PFH2005] 622. Within the XMM source error circle there are 3 optical
sources. We request a 20 ks Chandra observation to localize the
position of the [PFH2005] 622 and to determine whether it is currently
brighter than the XMM flux of 6.9E-15 cgs.

Sequence Number: 703155

Title : X-ray Flux of the Narrow Line Seyfert 1 Galaxy WPVS 007 during an
unprecidented low UV flux state
PI: Grupe
Abstract: We have monitored the Narrow Line Seyfert 1 galaxy WPVS 007 with Swift
since 9.5 years. During this time it has shown a gradual decline in
its UV flux. While this is somewhat expected, because WPVS 007 has
shown an evolution of broad absorption lines seen by HST (Leighly et
al. 2009), in the February 21 Swift observation we noticed a sudden
drop in it's UV M2 magnitude/flux. A new Swift observation on February
28 not only confirmed this low state, it even showed that the UV flux
had dropped even more to an unprecedented low state in the UV since we
have started monitoring WPVS 007 in October 2005! We were just grated
to continue with weekly monitoring with Swift for the next few weeks
to follow the UV flux. However, we need to compare this UV flux with
the current flux in X-rays. While WPVS 007 showed X-ray flaring in
2010 and 2011, stacking Swift data since 2011 suggest that it has
decayed also in X-rays. WPVS 007 is a link between BAL QSOs and NLS1.

Sequence Number: 401689

Title : X-ray follow-up of a fast radio burst
PI: Petroff
Abstract: A new class of bright, isolated, potentially extragalactic pulses
called fast radio bursts (FRBs) is emerging in radio surveys. Only a
handful of sources are known to-date. No host galaxies or progenitors
have been identified, and some of the population s most basic
properties are still being determined. The only FRB ever followed-up
at X-ray wavelengths showed no transient X-ray emission in
observations beginning 8 hours after the event. Rapid response is
needed to determine if an X-ray counterpart exists. This would be the
first multi-wavelength detection of an FRB. Swift is unable to make
these observations as the source may be too faint for Swift and at the
moment the Swift telescope is moon constrained and cannot take
observations on this source.

Sequence Number: 401688

Title : Simultaneous UV and X-ray spectroscopy with HST and Chandra: observing
wind accretion onto a NS
PI: Oskinova
Abstract: We propose a direct experiment to probe the theory of HMXBs. Currently
we conduct the HST survey of HMXBs (PI Oskinova). The HMXB 4U1700-38
will be observed on Feb 22. From the analysis of the STIS spectra we
will determine mass-loss rate, wind velocity and clumping in the donor
star. We need simultaneously HETGS data to test how X-rays respond to
the changes in the wind. Such experiment was never done before. The
HETGS spectra will probe absorption, variability, and emission lines.
Simultaneous X-ray and UV observations will yield an unprecedented
insight on the processes operating in HMXBs. Chandra observed
4U1700-37 in 2003 (id 657) but in different phase. The RGS spectrum is
relatively featureless, while emission lines are prominent in the
HEGTS range. The HEG+MEG count rate varies erratically between 0.2 cps
and 20 cps. We request 15 ks to fully characterize the X-ray behavior.
Zero order will be most likely piled up, the +1 and -1 order will be
fully useful.

Sequence Number: 703154

Title : A second look for variability in the exceptional Swift J123205.1-1056
PI: Levan
Abstract: Swift J123205.1-1056 is a short, soft outburst detected by Swift. In
the error box is an AGN at z=0.134. CXO observations reveal a second
X-ray source on the stellar field of this AGN. If associated (the
probability of chance alignment is low) it has L_X ~ 1e43 ergs/s. This
luminosity suggests either an "afterglow"-like event, or if persistent
a hyperluminous, non-nuclear X-ray source. In the former case it is
possible given the softness of the burst that we may be observing a
tidal flare-like event, in which case a WD-IMBH disruption within a
globular cluster in the galaxy is possible (this is a luminous galaxy
that may contain a high specific frequency of globular clusters, but
has little/no star formation). A repeat of the earlier CXO
observations will allow us to assess variability in the source. Strong
variability would point to a transient event, most likely related to
the gamma-rays. No variability would imply a persistent HLX, but would
still be of considerable interest.

Sequence Number: 502489

Title : Understanding the nature of the peculiar transient Swift
J123205.1-105602
PI: Troja
Abstract: Swift recently triggered on a short duration transient dubbed Swift
J123205.1-105602. Its unusual soft spectrum seems not to be consistent
with a typical short-hard GRB, and its nature is still not well
understood. An optical counterpart was found at the edge of a nearby
galaxy at redshift z=0.093, placing this event within the sensitivity
of advanced LIGO/Virgo. The X-ray emission detected by the Swift/XRT
appears constant, which is also unusual for a typical GRB afterglow.
We request rapid Chandra observations in order to: 1) accurately
localize the X-ray transient, robustly associate it to the optical
counterpart, and eventually detect possible contaminating sources
within the XRT point spread function; 2) constrain the spectral shape
in order to better understand the nature of this object (e.g. neutron
star merger, shock breakout, tidal disruption event).

Sequence Number: 502488

Title : The unprecedented metamorphosis of SN2014C
PI: MARGUTTI
Abstract: The mass-loss history of massive stars is one of the least understood
yet fundamental aspects of stellar evolution. HOW and WHEN do massive
stars lose their hydrogen envelopes? This central, still-open question
motivates our present investigation. Here we ask for a continuation of
our Chandra program to map the unique situation of the interaction of
a hydrogen-stripped supernova 2014C with a thick, hydrogen-rich shell
ejected by the progenitor star, as part of our multi-wavelength (mm to
gamma-rays) follow-up. Our primary goal is to constrain the density
and location of the material in the immediate environment of SN2014C,
and hence the mass-loss history of its stellar progenitor.

Sequence Number: 502487

Sequence Number: 502486

Sequence Number: 703152

Title : A High-resolution Spectrum of an Unprecedented Tidal Disruption Event
PI: Miller
Abstract: ASASSN-14li is the best possible tidal disruption flare (TDF). Its
host galaxy is at z = 0.02, whereas the prior X-ray bright event
(Swift J16444) was at z = 0.35. The position of this transient is
within 0.04" of the host galaxy. The source was previously quiescent,
and the optical spectrum - both before and after the flare - are
inconsistent with an active Seyfert nucleus. The most recent flux (Dec
2) measured with the Swift XRT is 2 E-11 erg/cm2/s in the 0.2-2.0 keV
band. A moderately deep integration will give a spectrum that should
compare well with Seyfert spectra. There is only weak galactic
absorption along the line of sight to this source (few E+20 cm^-2),
meaning that the low temperature emission (kT = 66 eV) will give an
excellent spectrum at long wavelengths. If the disrupted gas is
illuminated by the central engine, it is reasonable to expect
optically thin line emission on top of a thermal continuum. Please
see: http://www.astronomerstelegram.org/?read=6777

Sequence Number: 703152

Sequence Number: 401686

Title : A second HLX-1-like object in CXO J122518.6+144545
PI: Heida
Abstract: Intermediate mass black holes are crucial as building blocks for
supermassive BHs, but observational evidence for their existence is
still scarce. The brightest ULXs may be good IMBH candidates: the
strongest case is ESO 243-49 HLX-1 (Farrell et al. 2009), an X-ray
source that reaches a luminosity of more than 10E42 erg/s. It is
thought to host a BH of ~20,000 solar masses. Up until now, HLX-1 is
the only known object of its kind. Most candidate ULXs with comparable
luminosities have turned out to be background AGN. Finding more HLX-1
like objects would be an important step forward in the search for
IMBHs. We have investigated the X-ray source CXOJ122518.6+144545
(J1225; Jonker et al. 2010) with Chandra. It was found in an
observation from 2008, at a luminosity of ~2E41 erg/s, making it the
second most luminous ULX after HLX-1. We did not detect the source in
November 2012 and in April and July 2014, but in our last observation
on November 20 it was again visible at ~5E40 erg/s.

Sequence Number: 401685

Sequence Number: 502485

Title : Deep Chandra observations to put the deepest limits to the density of
the environment around a Type Iax SN
PI: MARGUTTI
Abstract: PSN J12215757+0428185 is a young Type Iax SN. It exploded in M61 and
it is the nearest Type Iax ever found. Here we ask for 20ks of Chandra
observations to constrain the density of the very close environment,
shaped by the mass-loss history of the progenitor system before the
explosion. This observation will allow us constrain the nature of the
progenitor system of this new kind of stellar explosions.

Sequence Number: 703151

Title : An unusual brightening of a non-active galaxy nucleus
PI: Feng
Abstract: NGC 247 is a dwarf or intermediate spiral galaxy at a distance of 3.4
Mpc. Past observations suggest that there was no activity of the
nuclear black hole. We conducted an XMM observation of NGC 247 on 2014
July 1, which serendipitously detected a bright X-ray source
coincident with the nuclear position (within 2 arcsec) with a
luminosity of 2E39 erg/s in 0.3-10 keV. The most recent observation
before that one was made on 2011 Feb 1 with Chandra. There was no
detection in the nuclear region, giving an upper limit of 1E37 erg/s.
If the new X-ray source is indeed due to the nuclear black hole
activity, its sudden brightening suggests that it may have tidally
disrupted a star some time between 2011 and 2014, or start to accrete
a stream of gas at a low rate. Either will be of great interest due to
its rarity and the small distance. A sub-arcsecond position accuracy
is needed to determine if the X-rays arise from the nucleus.

Sequence Number: 703150

Title : A candidate 30,000 solar mass black hole
PI: Gallo
Abstract: The target of this request is a newly discovered 30,000 solar mass
black hole candidate. As part of a follow-up spectroscopic campaign of
SDSS dwarf galaxies with optical signatures of AGN activity (Reines+
2014, ApJ, 775, 24), we recently acquired high resolution
Magellan/MagE spectra of a ~10^9 solar mass galaxy with narrow line
signatures of an AGN. The MagE spectrum clearly reveals the presence
of a broad H_alpha component that was only marginally detected in the
SDSS spectrum. Using standard virial techniques, the measured FWHM and
luminosity correspond a black hole mass of 30,000 solar masses. The
galaxy is a face-on disky dwarf with low Galactic absorption at a
distance of ~100 Mpc. We request 20 ksec with ACIS-S. In conjunction
with the optical diagnostics, the detection of a >10^40 erg/s, point
like X-ray source at a position consistent with the galaxy nucleus
would provide compelling evidence that this dwarf galaxy hosts the
smallest supermassive black hole reported to date.

Sequence Number: 502479

Title : Measuring the period derivative of the newly discovered magnetar SGR
1935+2154
PI: Rea
Abstract: Chandra observed SGR 1935+2154's outburst on the 15th and 28th of July
2014 for 9ks (ACIS-S, TE-mode) and 75ks (ACIS-S CC-mode). We detected
for the first time highly significant, >10sigma, pulsations at a
period of 3.24498(1) s (1 sigma c.l.), confirming it as a magnetar
candidate. Folding directly with this period the first observation we
detect the signal at a lower significance, deriving a period
derivative upper limit of about 2x10^-10 s/s was inferred. Swift
cannot see the signal because the source is too faint. We have
activated our XMM-Newton ToO program to keep monitoring the source,
but the XMM visibility will start on September 27th. We ask here for a
30ks DDT observation with ACIS-S CC-mode around late August to keep
the phase-coherence of our timing solution. This will allow the
determination of the period derivative of this new magnetar, crucial
to define the dipolar surface magnetic field of this object, then
identifying it as a highly-dipolar or low-dipolar magnetar.

Sequence Number: 200968

Title : The new outburst of the EXor V1180 Cas as observed at X and NIR
wavelengths
PI: Nucita
Abstract: EXORs are pre-main sequence stars that show recurrent luminosity
changes of short duration superposed to longer quiescence periods, see
e.g. Audard et al. 2014. Although a general consensus exists about the
nature of such outbursts (i.e. events of enhanced magnetospheric
accretion from the circumstellar disk), the physical mechanisms
regulating the outbursts and how these latter affect the circumstellar
disk structure and its evolution are not clarified yet. We recently
started an observational programme on this class of objects (EXORCISM,
EXOR OptiCal and Infrared Systematic Monitoring, Antoniucci et al.
2013). Optical and near-IR studies of EXORs rapidly increased in the
last decade but little is known about the X-ray properties, in
particular whether X-rays come from the corona of the star (being in
this case unaffected by the outbursts) or, conversely, originate in
accretion events.

Sequence Number: 401615

Title : Chandra/H.E.S.S. follow-up of PSR B1259-63 gamma-ray flare
PI: Bordas
Abstract: PSR B1259-63 is undergoing a flare emission in gamma-rays (ATel
#6204). Such a flare was observed for the first time in 2010,
accounting for almost 100% of the pulsar spin-down power. No flare
counterpart at higher/lower energies was observed at that time,
although the unexpected nature of the event made its MWL coverage
rather poor. We ask for Chandra DDT observations of PSR B1259-63 to
search for the flare X-ray counterpart (2 pointings x 5ksec each
during the next nights) and to monitor itsX-ray/TeV evolution (2
pointings x 5 ksec = 20 ksec from June 16th), in which H.E.S.S. will
observe the source simultaneously. The nature of the GeV flare and its
connection to the X-ray/TeV emission observed during PSR B1259-63
periastron passage makes simultaneous observations crucial. Next
Cherenkov observations will not be possible until 2021. No other X-ray
observatories are available for the requested dates (Swift XRT may not
be available next nights, see GCN 16349).

Sequence Number: 401614

Sequence Number: 502271

Title : Late-time X-rays to constrain the true energy, jet geometry and burst
environment of a GRB from the early Universe (z~6)
PI: MARGUTTI
Abstract: Among the most important parameters to constrain the GRB physics (both
jet launching mechanism and progenitor) are the energy scale, jet
geometry and the burst environment. Those can only be estimated
through broadband modeling of the late afterglow emission (radio to
X-rays). Of particular interest is to constrain the properties of the
z>6 population of GRBs that sample the star formation in the early
Universe (<1Gyr), and understand if they have unique properties when
compared to the overall population. This can only be done if reliable
estimates of the intrinsic properties of high-z GRBs and their
environments are available. Only 3 GRBs have been spectroscopically
confirmed at z>6 (050904, 080913, 090423). GRB140515A at z=6.32 offers
the opportunity to expand the sample. Chandra data acquired at
t+10days (after the flares) are crucial to map the spectrum above the
cooling frequency, thus enabling us to determine the true energy, jet
opening angle and environment of a rare z>6 GRB.

Sequence Number: 401613

Title : A Harder Look at the Bursting Pulsar
PI: Miller
Abstract: Observations of GRO J1744-28 with Chandra and NuSTAR reveal confusing
but potentially very revealing structure within the Fe K region. The
complex is either due to a very odd combination of charge states
within cospatial gas, or it represents double-horned emission line
structure from a truncated accretion disk. This is a significant
challenge to basic ideas of accretion in low-mass X-ray binaries, HETG
resolution can solve it.

Sequence Number: 401613

Sequence Number: 401612

Title : A rare opportunity to resolve the emission line complex in GRO
J1744-28
PI: Kennea
Abstract: Discovered Dec 1995, GRO J1744-28, AKA "The Bursting Pulsar", is one
of only two known objects to exhibit Type-II X-ray bursts. That
outburst lasted ~6 months, and since it has remained in quiescence.
Recently a coordinated effort by Swift, MAXI and Fermi confirmed GRO
J1744-28 to be in its first outburst in ~18 years. With Chandra we
entered the era of high resolution X-ray spectra, however Chandra has
only observed GRO J1744-28 in quiescence, obtaining a very poor
spectrum. ASCA observations (Nishiuchi et al., 1999) detected a 6.7
keV Iron line feature, which is strongly detected in new observations
by Swift. However, the poor spectral resolution of ASCA and XRT do not
allow us to discern the real nature of this feature. With such high
accretion rate, we might expect that the line complex is a blend of
neutral and high ionized lines from disk wind. Only Chandra HETG
observations have the sufficient resolution to pin down the nature of
the X-ray emission lines in GRO J1744-28.

Sequence Number: 401611

Title : The dynamical X-ray nebula powered by the high-mass binary PSR
B1259-63/LS 2883
PI: Pavlov
Abstract: PSR B1259-63/LS 2883 is the famous eccentric gamma-ray binary
(Pbin=3.4 yr, e=0.87) in which a pulsar orbits a massive O-type star.
Using ACIS observations of 2011 December 17 and 2013 May 19, 62 ks
each, we unexpectedly detected an extended (of about 4'' size)
structure, apparently moving away from the binary with v = 0.05c
(arXiv:1312.2654). Such a moving X-ray nebula has never been seen
before. An additional observation before 2014 January 30 is needed to
distinguish between two different interpretations of the extended
emission: (1) a fast-moving cloud of relativistic electrons loaded
with a large amount of baryonic matter; (2) a variable extrabinary
shock in the pulsar wind outflow. If (1) is correct, we will see the
cloud at the same position angle as in May 2013, while the shock would
be seen at a substantially different position angle (corresponding to
the orbital position change since May 2013; see
http://home.gwu.edu/~kargaltsev/B1259.html) if (2) is correct.

Sequence Number: 502269

Title : X-rays to probe the environment and the progenitor of Type Ia SN2014J
PI: MARGUTTI
Abstract: SN2014J has been recently discovered in M82, at a very close distance
of 3.7 Mpc. The spectra indicates a Type Ia supernova explosion. Type
Ia Supernovae have been employed as cosmic ladders to reveal the
accelerating Universe. In spite of their importance for Cosmology, a
key, fundamental question still remain open: Which stars are the
progenitors of these cosmic standards? We ask for deep X-ray
observations, to probe the environment around SN2014J down to
unprecedented limits. By timing the X-ray observations to the time of
the optical peak, and using the formalisms I developed in Margutti
2012 (ApJ 751 134) I will be able to probe densities as low as a few
d-10 Msun/yr (or a few particle/cm3), thus enabling us to distinguish
between symbiotic and double-degenerate progenitors. These limits
would be a factor 10 deeper than the any other limit presented in the
literature so far. It is also possible that this study will lead to
the first detection of X-ray radiation from a Type Ia SN.

Sequence Number: 200967

Title : X-ray driven evaporation of exoplanet atmospheres: discovery of a
uniquely suited test system
PI: Poppenhaeger
Abstract: The evaporation of exoplanetary atmospheres is thought to be driven by
high-energy irradiation. However, the actual mass loss rates are not
well constrained. Co-I Kipping has recently discovered that the star
KOI-314, an M1V dwarf at 65 pc distance, is orbited by two earth-sized
planets, the inner one of them rocky and the outer one gaseous (P_orb
= 14d and 23d). Other recent works have shown an abundance of small
rocky planets in very close orbits around their host stars, suggesting
that the stellar high-energy irradiation evaporates away gaseous
envelopes. KOI-314 is the first nearby system in which earth-sized
planets of both types are detected, allowing us to constrain the
efficiency of planetary evaporation if the stellar X-ray irradiation
is measured. We therefore propose a 10 ks Chandra ACIS-S pointing to
determine the stellar X-ray luminosity and hardness ratio. The
accuracy of the orbital solution decreases quickly due to
Transit-Timing Variations, which is why we ask for DDT.

Sequence Number: 401611

Sequence Number: 401610

Title : Catching the rebirth of a radio millisecond pulsar
PI: Patruno
Abstract: On 2013 Dec 10 we have discovered with a Swift/XRT observation, that
the low mass X-ray binary (LMXB) XSS J12270-4859 has recently changed
state from a quiescent-LMXB into a new anomalous faint state with no
signatures of accretion (ATel #5647). An NTT optical observation
suggests a transition around December 2012 in the opposite direction
to that of the "missing link" PSR J1023+0038 (that switched from a
radio millisecond pulsar (MSP), into an LMXB, Stappers et al.2013,
Patruno et al. 2013). A MSP may therefore be now active in XSS J12270.
We are currently completing the analysis of Parkes data to search for
the putative MSP. The Swift/XRT shows a faint source (1e32-1e33
erg/s). We want now to characterize the spectral behaviour with a 30
ks Chandra pointing. If we do not detect radio pulsations Chandra can
potentially tell us if the pulsar (and pulsar wind) are on even if the
radio pulsar is undetectable (as our preliminary Parkes analysis seems
to suggest).

Sequence Number: 502268

Title : Constraining the progenitor mass-loss and shock parameters around a
very unusual explosion: SN2013ge
PI: MARGUTTI
Abstract: Recent discoveries have shaken our current classification scheme of
supernova explosions. SN2013ge is such a case.The spectra we obtained
within 2 hours since discovery (on Nov 8th) revealed a very unusual
and blue continuum with no sign of H or He. Additionally, the
broadband light-curve of this transient showed an early blue peak
whose origin is unclear. Together, these findings place SN2013ge
outside ANY previously known SN category. We ask for a Chandra
observation to place a solid limit to the environment density (and
hence reveal the mass-loss history of the progenitor) and distinguish
between progenitor types. These observations will also allow us to
constrain the energy density in magnetic fields, a key but poorly
known parameter in SN shock physics. These observations are part of a
multi-wavelength program which includes optical, NIR (both photometry
and spectroscopy), UV and radio observations to obtain the best
constraints to what might represent a new type of SN explosion.

Sequence Number: 502266

Title : A search for absorption features in the afterglow of the unusual GRB
130925A
PI: Bellm
Abstract: GRB 130925A produced several emission episodes triggering Swift-BAT,
Fermi-GBM, and MAXI. The extraordinary length of this emission--over
10^4 seconds--would give GRB 130925A one of the highest total
durations ever observed for a gamma-ray burst. While the initial
bursting phase was similar to that of the the relativistic tidal
disruption event Swift J1644+57, starting at 10^4 seconds after the
trigger this event has entered a steady decay phase without new bursts
(www.swift.ac.uk/xrt_curves/00571830/). Its classification is thus
uncertain, as neither the long GRB class nor Swift J1644 provide
direct parallels. Our NuSTAR spectroscopy during the decay phase has
revealed evidence for a broad absorption feature never previously
observed for either GRB afterglows or for tidal disruption events.
Chandra observations will enable searches for lower-energy lines which
may constrain the ionization state of this unprecedented event.

Sequence Number: 502265

Title : GRB130831A: the birth of a magnetar
PI: De Pasquale
Abstract: Follow-up observations by XRT, UVOT, and ground facilities show Swift
GRB130831A to be an interesting and unusual long GRB at z=0.48, with a
bright optical afterglow. The X-ray light curve of this event
(www.swift.ac.uk/xrt_curves/00568849) displays a rare extremely steep
break from a power-law decay of 1.1 to 5 at ~10^5 s. The standard
forward-shock (FS) fireball model cannot explain the steepness of this
break. Instead it is the signature expected from the spin-down
emission of a newly-born magnetar seen before in short GRBs (Rowlinson
et al. 2013), but only once so far in a long GRB (070110, but 130831A
is a far superior example because the break is much later and we have
better coverage at other wavelengths). With the magnetar emission now
gone, we can measure the FS emission at nu > nu_c (with Chandra; it's
too faint now for Swift) to infer the total energy imparted to the
ejecta and have the first ever measurement of the efficiency of a
magnetar as central engine of a long GRB.

Sequence Number: 502264

Sequence Number: 502037

Title : The Energetics of the High-Redshift GRB 130606A
PI: Berger
Abstract: GRB 130606A at z=5.91 is only the fourth burst at such high redshift
with detected X-ray, optical/near-IR, and radio emission. The data
quality across the spectrum exceeds that of all previous events,
thereby providing a unique opportunity to study the energy scale and
local environment of a massive star explosion in the first Gyr after
the Big Bang. This will allow us to compare the progenitors of the
most distant GRBs to their more typical cousins at redshifts of z~1-3.
The energy scale will shed light the the nature of the explosion,
while the local density will track mass loss from the progenitor prior
to its demise, a direct clue to its nature. Of particular interest is
a measurement of jet collimation that will provide a measure of the
true energy release; strong evidence for such a "jet break" requires
an achromatic break from radio to X-rays. We will combine the
requested Chandra observation with extensive radio and optical/near-IR
data to decipher the GRB properties.

Sequence Number: 601099

Title : A direct constraint on the mass of an IMBH candidate in NGC 2276
PI: Roberts
Abstract: Although long predicted and searched for, a population of
intermediate-mass black holes (IMBHs) has yet to be detected in the
local Universe. We have recently published a small sample of luminous
ULXs that behave like IMBHs in the low/hard state (Sutton et al. 2012
MNRAS 423 1154). If they are in that state, we expect to see steady
radio jets; from these we can directly measure the black hole mass
using quasi-simultaneous X-ray & radio observations to place an object
on the fundamental plane (see e.g. Merloni et al. 2003 MNRAS 345
1057). In VLA follow-up of the sample an IMBH candidate in NGC 2276
was shown to sit at the centre of two extended radio lobes. We have
now been awarded European VLBI network (EVN) observations to attempt
to detect its radio core. Here we ask for quasi-simultaneous Chandra
observations, necessary to resolve the IMBH candidate from two nearby
(within ~5") ULXs and provide the X-ray data point that will allow us
to measure the mass of the black hole.

Sequence Number: 702923

Title : The unusual state of Mrk 590
PI: Mathur
Abstract: Seyfert 1 galaxy Mrk 590 is presently in an unusual state. Its X-ray
soft-excess has disappeared, its optical continuum has practically
vanished, its optical broad emission lines have disappeared, and it
shows the presence of a relativistic outflow. Even the narrow emission
lines have changed. All these observations could be related to each
other, but were taken years apart. We have an approved DDT on HST to
check if the UV continuum and UV broad emission lines have also
vanished and we request contemporaneous Chandra DDT to look for the
presence/ absence of the soft-excess. Together they will help
understand the common underlying cause which could be low accretion
rate relative to Eddington. They will also answer some long-standing
questions in AGN physics such as: What is the origin of the
soft-excess? What is the origin of the broad emission line region? Mrk
590 provides us with an unique opportunity find the underlying physics
related to these apparently disparate phenomena.

Sequence Number: 401541

Title : An intermediate-mass black hole candidate in NGC 404
PI: Kaaret
Abstract: Discovery (Reines et al. 2011, Nature, 470, 66) of a massive black
hole (MBH) in a star-forming dwarf galaxy has shed light on the
relation between MBHs and galaxy formation and evolution. Optical
observations of the star-forming dwarf galaxy NGC 404 suggest it hosts
a 4.5E5 solar mass BH. EVLA observations by Nyland et al. 2012
combined with archival Chandra data show a radio/X-ray source
consistent with a ~1E6 solar mass BH. We have approved European VLBI
Network (EVN) observations to image NGC 404 at 5 mas resolution,
enabling us to eliminate alternative interpretations (SNR, star
forming region). We request contemporaneous Chandra observations to
determine the X-ray state of the source. The source is too dim for
Swift and only Chandra will resolve the BH from surrounding diffuse
emission. In 15 ks, we expect 18 counts in the 2-10 keV band enabling
detection of hard X-ray emission from the BH.

Sequence Number: 401540

Title : Chandra observation of the newly discovered transient IGR J18245-2452
PI: Papitto
Abstract: IGR J18245-2452 is a newly discovered X-ray transient located in the
globular cluster M28 (ATel #4925), which showed a thermonuclear type-I
X-ray burst proving its NS accreting nature (ATel #4959). Optical and
radio counterparts have been proposed (ATel #4981,5003) and a
separate Chandra TOO has been approved to check the source location.
We proposea 60 ks Chandra observation with the HRC to check for any
additional close-by sources in the crowded environment of the
cluster, and to study variability of its emission.

Sequence Number: 100095

Title : High Latitude Charge Exchange X-rays from Comet PANSTARRS in the Cold
Polar Solar Wind
PI: Lisse
Abstract: For the 1st time since the 1996 discovery of cometary X-ray emission,
Chandra can characterize the solar wind in the heliosphere AUs above
the ecliptic plane using the very active Comet PANSTARRS (C/2011 L4).
At +83o latitude the comet will encounter the low density, low
ionization temperature polar solar wind, entirely lacking in O+8 ions,
deficient in O+7 ions, and rich in O+6 ions. The Chandra Comet
PANSTARRS observations will also extend the observed regime of CXE
emission to much lower wind densities and temperatures. The polar wind
should produce an ACIS-S spectrum with no OVIII charge exchange lines,
very weak OVII lines, and unusually strong OVI lines. Thus we will use
ACIS to search for weak CXE lines due to highly stripped CNFeMgNeSi
solar wind ions normally dominated by OVII and OVIII at 500-800 eV,
and detect OVI at 0.11 keV using the sensitivity of Chandra's HRC-I
camera to extremely soft x-rays. 3 identical visits are requested to
allow for solar wind variability.

Sequence Number: 100094

Sequence Number: 100093

Sequence Number: 702922

Title : Confirm the Nuclear Origin of the Post-flare Hard Spectrum from a
Tidal Disruption Event Candidate
PI: Lin
Abstract: Stars approach a SMBH can be tidally disrupted and subsequently
accreted. Such kind of tidal disrupt events (TDEs) provide a unique
way to find and study inactive SMBHs and may also provide an important
mechanism of growing them. Only about twenty such candidates have been
reported. Following-up of such events is important to constrain their
long-term evolution to help to pin down their nature and strengthen
the TDE theory. TDEs show large dynamic ranges on timescales of years,
allowing to search for possible state transition to test whether
accretion onto SMBHs is similar to that in stellar-mass BH X-ray
binaries. We now need an immediate Chandra observation to confirm the
nuclear origin of a post-flare hard spectrum from our TDE candidate
which has very soft spectra at the flare peak.

Sequence Number: 100097

Sequence Number: 100096

Sequence Number: 100095

Sequence Number: 100094

Sequence Number: 100093

Sequence Number: 901095

Title : Localizing NuSTAR J163433-473838: the First Source Discovered by
NuSTAR
PI: Tomsick
Abstract: A goal of the NuSTAR mission is to study hard X-ray populations in the
Galaxy. While INTEGRAL has carried out a wide survey, uncovering many
new types of interesting and extreme sources (highly energetic PWNe,
new types of HMXBs, etc.), NuSTAR emphasizes going deeper into the
Galactic plane to look for hidden populations. NuSTAR recently found
its first new source, NuSTAR J163433-473838, during an observation of
the Norma spiral arm region. In addition to searching for known
sources in SIMBAD, CSC, etc., we are confident that it is a new source
as Chandra did not detect it during an observation in mid-2011. We are
looking for compact objects in regions with star formation to look for
faint HMXBs that are early in their evolutionary process or perhaps
magnetars or black holes that are expected to be associated with high
mass stars. We are requesting a Chandra observation to localize the
source in order to search for counterparts (e.g., near-IR) to
determine its nature.

Sequence Number: 300318

Title : Understanding the X-ray temperature vs life time dependence of novae
PI: Henze
Abstract: What determines the life time of post-nova outburst supersoft X-ray
sources (SSSs)? A recent fast optical nova in M31 (ATels #4765,4768)
was detected surprisingly early (8 d post-discovery) in a Swift XRT
ToO. An XMM-Newton ToO was granted and unexpectedly revealed a
low-temperature SSS. Later, repeated Swift observations did not detect
the source after only 8 d of activity. This would not only indicate
the fastest SSS evolution of any known nova, it also places the object
well outside recently found correlations between nova parameters, as
only hot novae should evolve fast. However, due to its low-energy
response, Swift could not follow a more gradual decline in X-ray
luminosity and the target is now sun-constrained for XMM-Newton. We
strongly expect to be in agreement with current models and empirical
relations by detecting the nova with Chandra. A non-detection would
severely challenge our understanding of the connections between nova
observables.

Sequence Number: 502032

Title : Investigating the nature of the transient source in M 82
PI: Madej
Abstract: In our Swift X-ray monitoring of M82 we found a new bright transient
which position does not correspond to any of the known sources in this
galaxy. We would like to investigate the nature of this transient
source.

Sequence Number: 200910

Title : Observation of a possible 'orphan' GRB afterglow
PI: Vianello
Abstract: A GRB is highly beamed, while its afterglow is less so. In principle
this should allow to detect orphan afterglows , which has never
happened. The 1.5m MLS telescope of the CRTS discovered a peculiar
transient, which could be such an event. No GRB were detected at or
around that time. An obvious progenitor could be a low-mass star.
However, several co-added MLS images from before does not reveal the
source either, nor do all optical and X-ray surveys. Considering the
prototypical UV Ceti, this flare should have produced a brightening
above 7.5 mags, which would be extremely atypical (Kowalski et al.
2010). Observations with the Palomar 5m telescope (DBSP) and Palomar
1.5m showed no trace of the source (down to ~21st mag) 1 day after,
and 10 days later no photons were detected by Swift/XRT. This is
consistent with a typical afterglow with a power-law decay with
alpha=-1. Confirming the nature of this source would be extremely
valuable for our understanding of GRB afterglows.

Sequence Number: 300317

Title : Nova Mon 2012 as a luminous supersoft X-ray source
PI: Orio
Abstract: Chandra gratings observations of novae in outburst have constrained
the models of accreting and hydrogen burning white dwarfs (novae and
the possible type Ia progenitors) and are allowing unprecedented
discoveries in the nova physics. The supersoft X-ray phase of novae
isthe only way to catch a glimpse of the white dwarf itself, when
hydrogen burning is still ongoing but only a thin atmosphere sits on
top of it. The proposer of this observations has assessed the
theoretical prediction that the white dwarf effective temperature is a
proxy for the white dwarf mass and this has opened many new
possibilities (see Orio 2012, aeXiv 1210.4331). Some novae also show
supersoft emission because of very strong emission lines in the
ejecta, revealing a whole new physics (see also Orio 2012).This nova
is exceptional, it was only one of three detected with the Fermi LAT,
and extremely high energy phenomena seem to happen in the ejecta
(possibly because of large amounts of circumstellar material).

Sequence Number: 702920

Title : Sw1644+57: a relativistic jet that switched on and is now switching
off
PI: Tanvir
Abstract: Sw-J1644+57 was detected as a long-lived gamma-ray outburst in Mar
2011. Its unique H-E properties and location in the nucleus of a small
galaxy at z=0.35, suggested it was due to the tidal disruption of a
star by a 1-10 million Mo black-hole producing a relativistic jet. The
super-Eddington luminosity is understood by the jet pointing towards
us. Subsequent monitoring has shown the emission to decline roughly at
the expected -5/3 power-law for TDE fall-back, till a few weeks ago
when it abruptly "switched off". Our recent XMM data fixes the decline
to be a factor ~100 over only ~60d. Such a rapid shut-down of
accretion (~t^-25) seems implausible, so likely it represents the jet
launching mechanism turning off. We request a CXO observation, several
weeks after the XMM visit, to to establish whether the flux continues
to decline, or stabilises at a low level (eg. due to emission directly
from the accretion disk), thus shedding light on the poorly understood
process of jet production.

Sequence Number: 300316

Title : Grating Spectroscopy of early hard X-ray emission in Nova Mon 2012
PI: Ness
Abstract: The nova Mon 2012 of Aug9 2012 (CBET 3202) has fortuitously been
observed with initial gamma ray emission >100MeV before it was
discovered in optical. Optical observations show similarities with the
ONe nova V382 Vel (1999) (ATel4310). Recent Swift observations yield a
surprisingly bright hard spectrum of a collisional plasma with 3keV
temperature and NH=3E22 (ATel4321), ~10 times the inferred
interstellar value. For these types of spectra we have shown to have
robust model techniques yielding abundances, velocity structure and
ionization state. The only nova grating spectrum of early hard
emission is of RS Oph, but without a giant companion, the origin in
Mon 2012 must be different. Constraining the nova ejecta with a
grating spectrum will illuminate on possible mechanisms for the
production of the initial >100 MeV gamma-rays that may in fact be
general to all high velocity ejection events.

Sequence Number: 502021

Title : The outflow geometry of the short GRB 120804A
PI: Troja
Abstract: The angular size of the GRB outflow is a key ingredient in determining
the total burst energy release and the true events rate. These
parameters are a crucial test for any progenitor and central engine
model. However, despite years of intense follow-up observations, the
degree of collimation of short GRBs still remains a missing piece of
information. Only a few short GRBs display a long-lived, and
relatively bright afterglow, detected in the X-ray, optical, and radio
bands. In these cases meaningful constraints on the jet opening angle
can be placed. We therefore propose to observe the afterglow of
GRB120804A with Chandra a few days after the explosion in order to
search for a jet-break, which is a clean diagnostic tool for
constraining the outflow geometry.

Sequence Number: 502020

Title : 1E 2259+586: Detecting Particle Outflow from an Active Magnetar
PI: Kaspi
Abstract: Magnetars are a class of neutron stars for which the majority of the
radiative output is believed to be powered by the decay of large
(~10E14-10E15 G) magnetic fields. On 2012 April 28, as seen in our
regular Swift monitoring observations, one well-known magnetar, 1E
2259+586, in SNR CTB109, entered a period of enhanced flux (ATel.
4080),and simultaneously suffered a timing anomaly. One proposed
mechanism to explain such outbursts is particle outflow (Thompson et
al. 2000) where large amounts of plasma are advected from the magnetar
at relativistic speeds. This suggests the possibility of a transient
outflow that could result in a jet-like or nebular X-ray structure. A
detection of a transient, small-scale X-ray nebula would be strong
evidence in favor of this model.

Sequence Number: 501800

Title : Disclosing the position of the naked-eye-alike GRB120624B's afterglow
PI: Campana
Abstract: GRB120624B was detected by Swift and Fermi-LAT at very high energies,
but was Moon constrained for Swift follow-up. It is an extremely
bright burst, placing it in the brightest 1% of Swift and Fermi
bursts, only a factor of 2 fainter than the naked-eye GRB080319B. The
lightcurve shows much sub-structure, with hints of periodic behaviour.
A late 10ks Swift XRT observation located an X-ray afterglow candidate
at F_X~8e-14 ergs/s/cm^2. Such a faint X-ray afterglow is very
unusual. Bright bursts such as this one would typically be much
brighter at these times, by factor of ~10 (e.g. Gehrels et al. 2008).
Two deep NIR observations taken with VLT/HAWKI located a candidate,
but it is unusually faint too, and we cannot rule out an unrelated
source. This NIR source is not coincident with the X-ray source. Given
the unique nature of GRB120624B which appears unlike any previously
observed Swift burst, and the significant interest in tracking rare
Fermi-LAT bursts, we request a rapid Chandra ToO.

Sequence Number: 401435

Title : Unveiling an intermediate-mass black hole in the spiral galaxy NGC
4088
PI: Mezcua
Abstract: We have recently detected compact radio emission from the ULX N4088-X1
using the EVN at 1.6 GHz consistent with steady jets from a black
hole. A series of Swift observations obtained around the same time
found the spectrum to be very hard, consistent with the low/hard state
when steady jets are expected. The radio and X-ray luminosities are
consistent with a black hole mass of ~10,000 Msun, however to
accurately measure the mass using the fundamental plane of accreting
black holes we need observations at 5 GHz. To this end we have been
awarded additional 5 GHz EVN observations in early June, and we
request a simultaneous Chandra DDT observation to accurately measure
the mass and confirm the association between the X-ray and radio
emission (for which a sub-arcsecond X-ray position is needed). If
confirmed, this would be the first detection of steady jets from an
intermediate mass black hole (IMBH), and would provide the first
accurate mass measurement of an IMBH.

Sequence Number: 401434

Title : An HETGS Observation of Extreme Activity in 4U 1630-47
PI: Neilsen
Abstract: The black hole candidate 4U 1630-47 recently entered an extremely
bright, active state in its outburst, with X-ray flux varying by a
factor of 4 on timescales of 1 day (mean flux ~0.3 Crab) and strong
hard X-ray emission (as seen by MAXI, Swift/BAT). Our recent
HETG/Suzaku observations of the source in a soft, steady state at 50%
lower flux revealed deep absorption lines from an extremely massive
disk wind. The new active state represents an excellent opportunity to
study how such massive winds respond to strong X-ray variability and
state changes, which have never been probed in 4U 1630-47. Our
proposed 20 ks CC-mode observation will reveal any long- and
short-term modulation in the massive disk wind, while additionally
providing simultaneous probes of any rapid X-ray variability and
changes in the X-ray continuum.

Sequence Number: 401430

Title : Swift J1753.5-0127 in the soft state: signatures of an outflowing
wind
PI: Soleri
Abstract: Miller et al. (2006, Nat., 441, 953) detected absorptions lines in the
Chandra spectra of the black hole GRO J1655-40 in the soft state,
associated with a disc wind. Ponti et al. (2012, MNRAS, 422, L11)
showed that disc winds are common among black holes in the soft state
(but see Neilsen & Homan 2012, ApJ, 750, 27); these winds are more
easily detected in nearly edge-on sources. Swift J1753.5-0127 is a
black hole candidate which has been active since May 2005 and it is
now entering the soft state (Atel #4056). From a fit to a broad Fe
line, Hiemstra et al. (2009, MNRAS, 394, 2080) found that the system's
inclination is high, although no dips or eclipses were observed. We
ask for a 20 ks Chandra observation to detect signatures of a disc
wind, set constraints on the driving mechanisms (which are still
unclear) and estimate the mass loss in the wind. If we also detect the
broad Fe line we can compare its properties to those in the hard
state.

Sequence Number: 300312

Title : Nova LMC 2012 at high spectral resolution
PI: Drake
Abstract: Nova LMC 2012 is the first X-ray bright nova easily accessible to
Chandra gratings to have occurred in Swift Era. Unlike the highly
uncertain distances of novae in the Galaxy, the LMC is at known
distance and nova luminosities can be precisely measured.
Spectroscopic evidence and the fast evolution of the event suggests it
might be a recurrent nova. High resolution X-ray spectra will allow
diagnosis of the radiatively-driven outflow through line profiles, and
will provide a chemical composition snapshot of the supersoft source
envelope. Existing grating observations of novae have shown a diverse
array of spectral features, but recently a pattern has emerged in
which emission lines are stronger for smaller inclination angles. A
Chandra LETG spectrum will provide key insights into the emission
geometry and will help diagnose the processes underlying the
radiatively-driven outflow in what will be a close to Eddington
Luminosity source.

Sequence Number: 401429

Title : An HETGS Observation of the Transient MAXI J1305-704
PI: Miller
Abstract: MAXI J1305-704 is a new X-ray transient, which has come up to a flux
level of 0.07 Crab (see ATEL 4044) and appears to be in a fairly soft
state. Dips have been observed in the X-ray flux, indicating a high
inclination, and possibly also a very short orbital period. This
represents an excellent chance to study the disk atmosphere in this
source, and connections to disk winds. Importantly, the line of sight
column density forthis source is low (1-2 E+21) and will enable
sensitive spectroscopy across the full HETGS band. A 30 ksec
observation of MAXI J1305-704 will yield approximately 1 million
photons in the MEG and HEG, at current flux levels.

Sequence Number: 501797

Title : Supernova PTF 11qcj: first discovery of a radio luminous Ibn
supernova
PI: Corsi
Abstract: PTF 11qcj is a Ibn supernova (SN) discovered by PTF. Its spectra show
He emission lines, related to the interaction with a He-rich dense
shell. Only 4 SNe like this are known, the most famous is SN 2006jc.
11qcj is the only known case of a radio-loud Ibn SN. The Chandra X-ray
light curve of 2006jc supported the He-shell scenario, showing a flux
increase of a factor of 5 in the first 4 months after discovery,
different from the typical power-law decay of X-ray SNe interacting
with a circum-stellar wind. The two Chandra observations of 11qcj
reveal an X-ray luminosity 5x that of 2006jc (at a similar epoch).
Based on the template X-ray behavior of 2006jc, and on the radio
observations we collected so far for 11qcj (the radio emission seems
to track the X-ray behavior), we expect that 11qcj X-ray light curve
is now decreasing. We ask to re-observe 11qcj with Chandra before it
becomes too faint, so as to measure the X-ray light curve FWHM and
constrain the thickness of the dense shell.

Sequence Number: 501796

Title : X-ray followup of type IIP SN 2011ja
PI: Ray
Abstract: We request a Chandra DDT observation of this IIP SN for 60 ks. In our
Chandra observation of 2012Jan10 (39.45 ks exposure, ObsID 13791) we
have detected the SN with 135 counts (0.3-3 keV, background
subtracted) in ACIS-S. A fixed-abs APEC model gives a good fit (kT=
1.6 +- 0.1 KeV and Flux (0.5-2 keV) = 8.8e-15 cgs, with excess
emission at 1.33 keV. The NEI model with free abundance of Mg XI
forbidden line at 1.334 keV can explain the line for a 3.69+/-1.37
fold overabundance of Mg (3 sigma). Both thermal & non thermal Inverse
Compton models can be conclusively ruled out. The line contains 21
counts. As the SN ages the forbidden line should decrease in strength
as gas comes into ionization equilibrium. Chandra observation will
confirm and model the existence of the Mg line and its evolution and
determine the SN ejecta structure. Stacked exposures can detect
further element lines. We have observed it with GMRT (ATel 3899).

Sequence Number: 200830

Title : X-ray irradiation and evaporation of a super-Earth exoplanet
PI: Wheatley
Abstract: The recent discovery that the super-Earth exoplanet 55 Cnc e transits
its 6th mag star provides the exciting opportunity to study the upper
atmosphere of a super-Earth for the first time. Our team has secured
HST DDT with the aim of searching for hydrogen escaping the planet (by
measuring absorption in Ly-alpha through two transits). The planet
density suggests that it may be composed largely of water, in which
case hydrogen evaporation may be expected from a photo-disassociating
super-critical ocean. We propose Chandra observations to measure the
X-ray flux of the host star at the time of both HST observations (on
Mar 7 and Apr 5). Exoplanet evaporation is thought to be driven by
X-ray irradiation, and combined X-ray/UV measurements are required to
measure the mass loss rate and determine the evaporation efficiency.
By measuring X-ray irradiation and the resulting evaporation through
two transits we can begin to study the response of a super-Earth
atmosphere to varying irradiation.

Sequence Number: 200829

Sequence Number: 501794

Title : Supernova PTF 11qcj: first discovery of a radio luminous Ibn
supernova
PI: Corsi
Abstract: PTF 11qcj is a Ic supernova (SN) discovered by PTF. Its spectra show
He emission lines, related to the interaction with a He-rich dense
shell. Only 4 SNe like this (called type Ibn SNe), are known. The
prototype is the famous SN 2006jc. The exceptional thing about 11qcj
is that it is radio loud: only this one case of a radio-loud Ibn SN is
know. The Chandra X-ray light curve of 2006jc supported the He-shell
scenario, showing a flux increase of a factor of 5 in the first 4
months after discovery, different from the typical power-law decay of
X-ray SNe interacting with a circum-stellar wind. The Chandra
observation of 11qcj at about 80d since discovery, reveals an X-ray
luminosity 5x that of 2006jc (at a similar epoch). Aim of this
proposal is to track the evolution of 11qcj X-ray light curve, so as
to determine its peak flux and timescale, that are crucial for the
broad-band modeling (currently, we are carrying out an extensive
follow-up campaign in radio, optical, and infrared).

Sequence Number: 501793

Title : Supernova PTF 11qcj: first discovery of a radio luminous Ic SN
interacting with an He shell?
PI: Corsi
Abstract: PTF 11qcj is a Ic supernova (SN) discovered by PTF on 2011 Oct 23. Its
spectrum on day 34 shows He I emission lines which are very rare,
suggesting this a Ibn: a Ic SN interacting with a He-rich cold dense
shell (CDS). Only 4 Ibn SNe are known, the best studied prototype is
the famous SN 2006jc. The Chandra X-ray light curve of 2006jc
supported the CDS scenario, showing a flux increase of a factor of 5
in 4 months, very different from the power-law decay of X-ray SNe
interacting with a circum-stellar wind material (CSM). However, SN
2006jc was undetected in radio. PTF 11qcj may represent the first
discovery of a radio luminous Ibn: our EVLA observations at 40 d
reveal it is 100x more luminous than 2006jc in radio. This suggests
strong CSM interaction which, based on 2006jc, makes a detection with
Chandra likely. We thus request a Chandra observation: measuring the
X-ray luminosity of this event will allow us to constrain the density
of the CDS and confirm the Ibn nature of 11qcj.

Sequence Number: 401427

Title : Chandra Astrometry of a New ULX in NGC 891
PI: Hodges-Kluck
Abstract: A 08/2011 XMM observation of NGC 891 shows a bright (L_X ~ 2E40 erg/s;
F_X ~ 1E-12 erg/s/cm^2) new ULX near the disk. It is absent in
archival X-ray observations. Variability in Swift monitoring and the
absence of bright optical or radio counterparts rule out a SN. As a
bright ULX that recently "turned on" and whose spectrum indicates a
hot (kT ~ 1 keV) disk, the source may be an extreme example of
super-Eddington (5-50 L_Edd) accretion. Deep archival HST images
reveal a potential counterpart--a star cluster--within the 2" X-ray
error circle, but it is only 0.5" across. A better position is a
prerequisite for proposing deep spectroscopic follow-up, and the lack
of radio or optical counterparts in follow-up observations makes CXO
the only option. We expect an ACIS-S count rate of 0.07-0.2 cts/s, and
request 2 ks of DDT time to obtain 150-400 cts, thereby sampling the
PSF extremely well. Although a snapshot is susceptible to flaring, the
ULX is extremely bright.

Sequence Number: 501792

Title : Studying the physics of outbursts in the Westerlund 1 transient
magnetar laboratory
PI: Israel
Abstract: CXOUJ1647 is a transient magnetar which is currently in outburst
(September 2011). The previous one occurred in 2006. Preliminary
analysis of the timing and spectral parameters of the new outburst
suggest a different behaviour with respect to the 2006 event. The main
aims of the DDT request are: the detection of Pdot variations and
therefore of variations of the B-field topology during the 2
outbursts, and monitoring both the spectral and timing evolution in
order to compare them with those of 2006. In particular, the way the
parameters of the two events evolve will allow us to answer to the
following questions: Are all magnetar outbursts originated by large
displacements and/or cracks of the neutron star surface? Are the hot
spots originated by the outburst always occurring on the same places ?
We note that Chandra is currently the only mission able to point to
the source and to achieve a phase accuracy large enough for keeping
the coherency until the next visibility window.

Sequence Number: 501791

Title : Chandra Observations of the Nearest Type Ia SN in 25 Years
PI: Hughes
Abstract: No SN Ia has been detected in the X-ray band during outburst. The most
careful limits have been set using a 20 ks Chandra observation of SN
2002bo in NGC 3190 (22 Mpc), which was observed 9.3 days after
explosion (Hughes et al. 2007), resulting in limits on the
circumstellar medium (CSM) of w = \dot M/ v_w < 1.2E15 g/cm, assuming
a wind density profile \rho_w = \dot M/(4\pi v_w r^2). This limit is
comparable to the limits set by the nondetection of H\alpha flux from
SN 1994D and SN 2001el, although they are less constraining than
limits set in the radio (Panagia et al. 2006). X-ray constraints are
based on direct calculation of the expected emission using
well-understood physics (i.e., bremsstrahlung emission,
Comptonization), while radio limits are subject to large systematic
uncertainties because the efficiency for generating synchrotron
radiation in the shocked wind and ejecta is not known. We will work
with Nikolai Chugai to model and intepret the results.

Sequence Number: 401425

Title : Chandra spectroscopy of the X-ray spectrum of the newly discovered
accreting millisecond pulsar IGR J17498-2921
PI: Di Salvo
Abstract: Papitto et al. (2011, ATel #3556) reported the discovery of a coherent
pulsed signal from the hard X-ray transient IGR J17498-2921 (Gibaud et
al. 2011, ATel #3551) at a frequency of 401 Hz, very similar to the
spin frequency of the first discovered Accreting Millisecond Pulsar
(AMSP) SAX J1808.4-3658. Taking advantage from the reported position
of the source (ATels #3558, #3559) we propose to observe this source
with Chandra/HETG in order to perform X-ray spectroscopy of the X-ray
spectrum of this interesting source and to get invaluable information
on the innermost emitting region. The PCA spectrum shows evidence of a
strong and broad iron emission line at 6.4 keV (sigma = 0.8 keV).
Chandra will be able to confirm that the line is produced at the inner
accretion disc. In this case, fitting with self-consistent reflection
models will give important information on the position of the
magnetospheric radius and on the neutron star magnetic field.

Sequence Number: 401425

Sequence Number: 501789

Title : Is Swift J1834.9-0846 a magnetar related to SNR W41 and HESS
J1834-087?
PI: Kargaltsev
Abstract: J1834.9-0846 triggered the Swift/BAT and the Fermi/GBM on August 7,
2011. Although an SGR-like event was detected in both cases, a spin
period has not yet been found. Our ToO with RXTE will take place on
August 9. We observed the field with Chandra (Misanovic et al. 2010),
searching for a counterpart to an unidentified TeV source HESS
J1834-087 inside SNR W41. We found a point source, CXOU
J183434.9-084443, and offset extended emission. We re-examined these
Chandra (and archival XMM) data and found no point source at the XRT
position of J1834.9-0846, which, however, falls within the extended
structure seen in the Chandra and XMM images. We request 15ks with
ACIS-S to measure the spectrum of the new source, look for possible
compact PWN and pulsations, and perform phase-resolved spectroscopy
and energy-resolved timing. The Chandra data will be jointly analyzed
with the existing HESS and Fermi data. We will use 1/8 subarray to
probe periods as short as 0.4 s.

Sequence Number: 501788

Title : Resolving the mystery of GRB 110709B
PI: Levan
Abstract: We recently observed GRB110709B under our c12 program. This burst was
both very dark (betaOX < -0.4), and unusual in triggering Swift/BAT
twice (separated by ~15 mins). This could indicate a high-z GRB, a
gravitationally lensed burst, or of (another) novel mechanism for GRB
production. Our CXO imaging showed two objects within or close to the
XRT error circle: the 1st (1.2" from XRT centroid) coincides with a
brightening radio source, presumed to be the GRB afterglow; the 2nd
lies at 2.7", and has near identical brightness. The second object may
also be associated with an optical source (which shows weak archival
evidence for variability), but the X/O offset is surprisingly large
(~0.8"). A second CXO visit to search for variability would greatly
clarify this situation. Is the 2nd source simply a chance foreground
object? Does the 1st source behave like a conventional X-ray
afterglow? The major followup devoted to this most unusual GRB makes a
strong case for another visit.

Sequence Number: 501567

Title : Determination of the true nature of Swift J1822.3-1606
PI: Kouveliotou
Abstract: Swift J1822.3-1606 was detected with the BAT during a ground search of
the data; it also triggered the Fermi/GBM when it emitted a series of
~5 Soft Gamma Repeater like X-ray bursts, each one lasting ~ 5 ms. We
observed the persistent emission of the source with the RXTE/PCA and
confirmed the pulse period of 8.4377585 s. Moreover, we determined a
very high pulsed fraction of the signal of at least 41%. This pulsed
fraction is highly unlikely for an SGR. The source could well be
another Swift J1626.6-5156 (most likely a Be-X-ray binary) or
alternatively, another rotation powered pulsar like PSR
J1846−0258, which was detected to emit SGR-like bursts. The
latter option was the first of its kind linking high B-field pulsars
to SGRs. We are seeking CXO/HRC observations of Swift J1822.3-1606 to
determine the most accurate source location, which will enable us to
identify the source counterpart in this congested region. The current
positional accuracy with Swift XRT is 3.5".

Sequence Number: 702582

Title : Swift J2058+0516: A Second Prompt Relativistic Outflow from a Massive
Black Hole?
PI: Cenko
Abstract: The recent discovery of the transient source Swift J1644 has revealed
a potential new class of high-energy outbursts. Like long-duration
gamma-ray bursts, these sources exhibit a prompt, dramatic energy
release which drives a relativistic outflow. However, the central
engine powering these events is the massive black hole at the center
of a normal galaxy. More recently, Swift has discovered another
high-energy transient, Swift J2058, with broadly similar high-energy
properties. Within the XRT localization (1.7" radius), we have
identified the likely optical counterpart as an absorption line galaxy
at z=1.185. At this redshift, the X-ray luminosity (4e47 erg/s) and
X-ray-to-optical flux ratio (12,000:1) are essentially identical to
that observed from Swift J1644. Here we request HRC-I observations of
Swift J2058 to a) provide precise astrometry (to establish or refute a
nuclear origin), and b) measure the variability time scale (to
constrain the mass of the accreting source).

Sequence Number: 401300

Title : Which M15 Source Is Now in Outburst?
PI: Sivakoff
Abstract: On May 16, MAXI detected an X-ray burst from the globular cluster M15.
Today (5/18) Swift confirmed that either the edge-on ADC source AC 211
or the ultracompact (22-min period) M15 X-2 is flaring (L~1.3E37). It
is unlikely that AC 211 is responsible as one does not expect to see
bursts from ADC sources. The standard paradigm for ultracompact XRBs
like M15 X-2 is that they "should" show stable mass transfer. The few
Chandra observations of M15 X-2 have not showed significant
variations, but today's measured luminosity was 10 times that
typically measured. The 17-minute ultracompact XRB in NGC 1851 has
shown variability by factors of >10 (Maccarone et al. 2010, MNRAS,
406, 2087), a behavior that remains unexplained. Determining that a
second ultracompact exhibits large variations would significantly
challenge the standard paradigm for accretion in ultracompact XRBs.

Sequence Number: 501563

Title : Confirmation of a New Pulsar Wind Nebula
PI: Miller
Abstract: We have recently discovered an extended source with dual ring-like
structure in a shallow Swift image in the Galactic Plane. The
structure is strongly suggestive of a pulsar wind nebula. A known B
star is plausibly associated with the extended source, which means
that the neutron star could be in a binary, and that we could capture
an image of a very young X-ray binary that will eventually become a
double neutron-star system. A short Chandra exposure of just 5 ksec
will be sufficient to confirm the structures suggested by the Swift
image, to obtain a spectrum with approximately 4000 photons, and to
enable multi-wavelength follow-up observations in the near future.

Sequence Number: 702581

Title : Chandra Follow-up of an Exceptional GALEX+PS1 Tidal Disruption Event
Candidate
PI: Gezari
Abstract: We propose for a DDT observation of a candidate tidal disruption event
(TDE) discovered in coordinated UV GALEX and optical Pan-STARRS1 (PS1)
observations. The long-lasting blue color (NUV-r < -1.2) during the
slow decay of the flare over 10 months of GALEX+PS1 monitoring is
unlike any known supernova behavior, and is consistent with the hot
blackbody emission and t^(-5/3) luminosity decay of a TDE. X-ray
observations are critical for determining the broadband SED of the
flare, which is theoretically expected to peak in the soft X-rays.
This flare would have satisfied our Chandra Cycle 11 TOO criteria when
it was discovered in 2010 June, however the first optical spectrum
taken on 2010 June 16 detected an isolated broad emission line that
was misidentified as Mg II at z=0.96. A later spectrum taken on 2011
April 7 revealed absorption features from the host galaxy at z=0.170,
indicating that the broad feature was in fact He II, a high ionization
line associated with TDEs!

Sequence Number: 401297

Title : Probing the neutron star crust of the new transiently accreting 11 Hz
X-ray pulsar in the globular cluster Terzan 5
PI: Degenaar
Abstract: A new bright transiently accreting neutron star was discovered in
Terzan 5 in 2010 October. We obtained a Chandra DDT observation in
February, ~2 months after the end of the outburst, and found the
neutron star a factor ~4 hotter than measured in archival Chandra data
(Degenaar & Wijnands 2011a,b). This indicates that the crust was
severely heated during outburst and that it is possible to observe the
crust cooling curve of this source. However, our target likely cools
considerably faster than previous studied sources, because the short
(~2 months) outburst duration only heated the outer layers of the
neutron star crust (see webpage specified below), which loose the
deposited heat already within months. We request a Chandra DDT
observation to further monitor the cooling curve and put important new
constraints on the neutron star crust: the slope of the cooling curve
directly measures the heat flux in the outer crust, hence the amount
and distribution of heat sources.

Sequence Number: 200735

Title : Hot wind and accretion in TW Hya
PI: Guenther
Abstract: We have recently discovered variability in X-ray indicators of
accretion in the CTTS TW Hya. We seek to use this to understand the
physics of accretion in our upcoming HST observations. We have been
granted 10 HST orbits and 15 CRIRES pointings to monitor the C IV 155
nm doublet and the He I 1083 nm line in TW Hya, the closest CTTS, to
correlate i) the hot wind ii) the cool wind iii) the photometric
period iv) the accretion. In existing HETGS data of TW Hya we see
variability in emission lines from the accretion shock on the star.
However, the densities in Ne IX and O VII indicate that today's shock
models are incomplete. A hot wind is the most promising candidate for
this missing component. Our HST observations will characterize the
wind and we ask for 20 ks Chandra time with LETGS/ACIS simultaneous to
HST to determine the state of accretion. The high effective area of
LETGS/ACIS gives > 100 counts in the O VII and Ne IX triplets, so we
can measure the density and temperature.

Sequence Number: 401295

Title : Searching for the pulsar powering the new TeV binary HESS J0632+057
PI: Torres
Abstract: We request 50 ks Chandra time to check for the existence of X-ray
pulsations from HESS J0632+057. The latter is associated with XMMU
J063259.3+054801 / Be star MWC 148 and has shown a recent increase in
X-ray activity, based on Swift-XRT monitoring (ATEL #3152). We have
used this and previous Swift observations (Falcone et al. 2010, ApJ
708, L52) to positively evaluate the Chandra visibility. HESS
J0632+057 was recently discovered (Aharonian et al. 2007, A&A, 469,
L1), and proposed to be a member of just a handle of such binaries
that emit in gamma-rays. Knowing about its composition is essential
for modeling (e.g., Mirabel 2006, Science 1759). Search for pulsations
from gamma-ray binaries with Chandra have provided the most stringent
upper limits yet (Rea et al. 2010, MNRAS 405, 2206), and its detection
would be a breakthrough for the understanding of these systems.

Sequence Number: 401293

Title : Observing the crust cooling in the 11 Hz accreting pulsar in the
globular cluster Terzan 5
PI: Wijnands
Abstract: We have intensively studied the crust cooling of accreting neutron
stars. We have focused on systems with outbursts lasting years to
decades for which observing the crust cooling is most feasible.
However, as already suggested in Brown et al. 1998 (see the link given
in the TOO Trigger criteria section) crust cooling might also be
observable for systems which have a low quiescent temperature and very
bright but short (weeks/months) outbursts. A recent new transient in
Terzan 5 reached ~1E38 erg/s and its outburst lasted at most a few
months. Combined with its very low quiescent temperature (Degenaar &
Wijnands 2011) this source is an ideal target to test this and to
provide valuable input to any crust-cooling model. Adding this source
to our sample will also be very important to understand the observed
differences between sources and whether this is related to their
different outburst properties and further put constraints on the
properties (ie the crust) of accreting neutron stars.

Sequence Number: 401292

Title : Measuring the Spin of the Black Hole Cgynus X-1, Phase 2
PI: McClintock
Abstract: We are about to submit a paper to Science on the near-maximal spin
(a/M>0.97) of Cyg X-1 [1]. This premier result is largely based on two
DDT Chandra (plus RXTE) spectra obtained last July, two weeks after
Cyg X-1 entered its soft state on 7 July. For these observations, the
Compton component was relatively strong ("scattered fraction" f=34%),
well above the established limit of reliability for our spin method,
which is f=25% [1]. In mid-October, Cyg X-1 entered a "supersoft"
state [1], and we now propose to obtain one additional Chandra
observation (HETG; TE mode; 12 ks) in order to secure our result. We
expect to obtain a Compton-weak spectrum with f<25% (like our 1996
ASCA/RXTE spectrum with f=24%) [1]. To date, our group has measured
the spins of 9 black holes, and this result for Cyg X-1 is distinctly
our most important and exciting [2]. REFERENCES: [1]
https://www.cfa.harvard.edu/~lgou/cygx1/cygx1.html [2]
http://arxiv.org/abs/0909.0169 AND http://arxiv.org/abs/1004.3558

Sequence Number: 501549

Title : Unveiling the nature of cyclic behavior in the period evolution of the
Anomalous X ray Pulsar XTE j1810-197
PI: Perna
Abstract: The goal of our analysis is to probe a possible long term (5 yr)
free-body precession of this neutron star for which we found several
indications based on a non-phase-connected timing analysis. Although
only 3 NS up to now have shown indication of precession, such evidence
strongly challenges our current understanding of the NS interior. The
standard picture of the outer core, in which superfluid neutrons
coexist with type II superconducting protons, requires revision. One
possibility is that protons are type I which would imply a significant
revision of our picture of the physical conditions in the NS core.
Another possibility is that the neutrons are normal in the outer core
which again affects our understanding of the physical state of NSs
core. The presence of long period modulation can shed light on the
physical properties of NS and thus help constraining its equation of
state

Sequence Number: 600982

Title : An Unusual Outburst from the Nucleus of the Quiescent Galaxy NGC 1589
PI: Filippenko
Abstract: As part of the Lick Observatory Supernova Search (LOSS), we have
recently identified an unusual optical outburst from the nucleus
(within 0.05";, or 10 pc in projection) of the nearby (d ~ 50 Mpc)
spiral (S0/a) galaxy NGC 1589. Over a decade of photometric monitoring
with LOSS, together with archival spectroscopy from the CfA Redshift
Survey, suggest the galaxy does not harbor an active galactic nucleus.
Likewise, the bright observed X-ray emission and complex H-alpha
emission profile do not appear to resemble any known Type II
supernova. We therefore believe this transient source (dubbed
NGC1589-OT) represents the most viable candidate for a tidal
disruption flare (TDF) ever discovered in real time. Here we request a
10 ks Chandra/ACIS DD observation to accurately constrain the X-ray
spectral properties (power-law vs. thermal) and environment (n_H) of
this unique, fascinating source. In a separate proposal, we are also
requesting HST time to get a UV spectrum of it.

Sequence Number: 501548

Title : Monitoring of the Crab Nebula
PI: Weisskopf
Abstract: Subsequent to the detection of a gamma ray flare in September, Chandra
has been used to monitor the structure and spectrum of the Crab
Nebula. This flare was first detected by AGILE (ATEL 2855)and had a
timescale of days. The event was also seen with the Fermi Satellite.
These S/C have also observed flaring at other times and with longer
timescales. The Sept. event has received international attention and
it appears that the flaring is not directly associated with the
pulsar, but with the nebular flux. The timescale indicates an emitting
region as small as 0.5-1.0 arcsec at two kpc. Chandra has shown that
there are many features of this scale in the nebula and that they are
constantly changing. It is essential that a viable baseline be
established in order to obtain useful information from future
observations triggered by another flare. We propose a series of
monitoring observations.

Sequence Number: 501547

Sequence Number: 501546

Sequence Number: 501545

Sequence Number: 501544

Sequence Number: 501543

Sequence Number: 501542

Sequence Number: 702511

Title : The bolometric luminosity of the z=7.08 QSO ULAS J1120+0641
PI: Simpson
Abstract: We have recently discovered the most distant QSO, ULAS J1120+0641, at
z=7.08, smashing the previous record of z=6.44. This object was
discovered by surveying 2250deg^2 of UKIDSS and SDSS, extending the
technique used by high-z QSO surveys into the near-IR. Based on its
rest-frame UV luminosity, the QSO is powered by a black hole of mass
~1e9Msun just 760Myr after the Big Bang. The presence of such a
massive collapsed object when the Universe was so young is a serious
challenge to models of structure formation and places strong
constraints on the growth of supermassive black holes in the early
Universe. We propose a CXO observation of ULAS J1120+0641 to measure
its X-ray flux. This will immediately provide a more reliable estimate
of its bolometric luminosity and black hole mass, and is also
necessary for us to determine the feasibility of a deep XMM spectral
observation to measure the X-ray photon index and Eddington ratio, and
compare its X-ray properties with those of other QSOs.

Sequence Number: 401291

Title : Confirming the low-mass X-ray binaries in the Kepler field
PI: Liu
Abstract: The Kepler mission has proved powerful in understanding the accretion
disks around compact objects for its un-interrupted monitoring
capability with time resolutions of minutes. Previous Kepler
observations of symbiotics and Cataclysmic Variables have successfully
probed the structures of the accretion flows around white dwarfs. In
the third and final Kepler cycle, we will seek to probe the accretion
flows around more compact neutron stars and black holes with Kepler
light curves, a regime never been studied before. There are no
existing studies of low-mass X-ray binaries (LMXBs) in the Kepler
field; we select LMXB candidates from ROSAT all sky survey (RASS)
sources in the Kepler field based on hardness ratios, X-ray-to-optical
ratios, and source extent aided by visual inspection. Here we propose
short Chandra observations for this sample of 15 LMXB candidates to
determine their exact nature and optical counterparts.

Sequence Number: 401290

Sequence Number: 401289

Sequence Number: 401288

Sequence Number: 401287

Sequence Number: 401286

Sequence Number: 401285

Sequence Number: 401284

Sequence Number: 401283

Sequence Number: 401282

Title : High resolution spectroscopy of the 11 Hz eclipsing pulsar in Terzan
5
PI: Bhattacharyya
Abstract: The observation of the unique neutron star low-mass X-ray binary
(LMXB) EXO 1745-248 during its current outburst holds the promise to
address several important scientific problems. These are (1) use of
narrow absorption and emission features to probe the ionized and
neutral components above the accretion disk of LMXBs (Jimenez-Garate
et al. 2003); (2) measurement of the disk inner edge radius from the
broad relativistic iron line, and hence to probe the strong gravity
regime and the neutron star parameters (Bhattacharyya and Strohmayer
2007; Cackett et al. 2008); and (3) measurement of the neutron star
radius-to-mass ratio from narrow surface atomic spectral lines during
thermonuclear X-ray bursts. An observation with Chandra is required
because (1) it has unique high-resolution spectral capability, and (2)
this satellite will be able to observe the source throughout the
outburst (which XMM-Newton and Suzaku cannot do because of Sun angle
constraints).

Sequence Number: 501540

Title : Study of spatial structure associated with a gamma-ray enhancement of
the Crab
PI: Weisskopf
Abstract: Both the AGILE and Fermi satellites detected significant variation in
the emission above 100 MeV from the Crab Nebula. Moreover, there
appears to be a 1100 day counter variation in the x-ray flux from the
nebula seen with a number of satellites (figure sent separately). The
source of the enhancement seems to be associated with the brightening
of a knot appearing in the vicinity of the pulsar as seen by our team
using both Chandra and subsequently HST. Only Chandra has the imaging
spectroscopic capability to study such features, which we would then
correlate with the gamma-ray flux.

Sequence Number: 501539

Sequence Number: 501538

Sequence Number: 501537

Sequence Number: 501536

Sequence Number: 501535

Title : Unveiling the nature of cyclic behavior in the period evolution of the
Anomalous X ray Pulsar XTE j1810-197
PI: Bernardini
Abstract: The goal of our analysis is to probe a possible long term (5 yr)
free-body precession of this neutron star for which we found several
indications based on a non-phase-connected timing analysis. Although
only 3 NS up to now have shown indication of precession, such evidence
strongly challenges our current understanding of the NS interior. The
standard picture of the outer core, in which superfluid neutrons
coexist with type II superconducting protons, requires revision. One
possibility is that protons are type I which would imply a significant
revision of our picture of the physical conditions in the NS core.
Another possibility is that the neutrons are normal in the outer core
which again affects our understanding of the physical state of NSs
core. The presence of long period modulation can shed light on the
physical properties of NS and thus help constraining its equation of
state

Sequence Number: 501534

Title : The first low-B soft gamma repeater: testing the magnetar model
PI: Rea
Abstract: On 2009 June 5 two SGR-like bursts were emitted by SGR 0418+5729
(Esposito et al. 2010, MNRAS, 405, 1787). Although this SGR showed all
the characteristics of SGRs' outbursts, a phase-coherent timing
solution over the first ∼500 d yielded no evidence for any pdot,
implying a 3σ u.l. on the B-field of <7.5 10^{12} G (Rea et al.
2010, Science in press). This is the lowest magnetic field ever
observed for a magnetar, and the first lower than the electron
critical B (~4x10^{13} G). Such a low a external dipolar B-field might
hide an internal high-B of ~10^{14} G, needed to trigger the
magnetar-like activity. The external B can be at most ~80 times the
dipolar surface B. We ask for an ACIS-S observation of 30ks in
December 2010 to keep the phase-coherence of our timing solution, and
hopefully have a final detection of the B-field of this low magnetic
field magnetar. If the B will end up to be < 10^12 Gauss, this would
pose serious difficulties on the magnetar model.

Sequence Number: 501533

Title : CHANDRA imaging of the cooling front after a high energy flare
PI: ferrigno
Abstract: The recently (Sept 19-21) observed flare of the Crab nebula above 100
MeV (ATEL 2855) is likely due to synchrotron emission of PeV electrons
injected either in the pulsar magnetosphere or close to the shock at
0.14 pc from the pulsar. If the injection happened close to the
pulsar, then high-energy particles are expected to reach the shock and
brighten it in one month time. If the flare is due to electron
injection at the shock, instabilities at the shock lead to an increase
of the injection rate which explains the observed gamma ray
brightening. At lower energies (ATELs 2856, 2858), the emission
remains stable because of longer cooling time. We expect an X-ray
counterpart of the gamma-ray flare in high resolution imaging
observation of the pulsar wind shock. With Chandra we can search for
structures/knots fading or moving (Hester et al. 2002). Follow-up
observations at later times (weeks to months) will be necessary to
follow the evolution of these structures.

Sequence Number: 501532

Sequence Number: 501531

Title : Search for new spatial structure associated with the gamma-ray
enhancement of the Crab
PI: Weisskopf
Abstract: It has just been reported (Atel 2555) that the AGILE satellite has
detected a significant variation in the emission above 100 MeV from
the environs of the Crab Nebula. A similar enhancement was seen at the
same time with the Fermi Satellite. If the source of this enhancement
is due to a new morphological feature (a new knot e.g. appearing in
the vicinity of the pulsar), then Chandra, because of its angular
resolution, is the only Observatory that can search for such a
feature.

Sequence Number: 401281

Title : Constraining the Spectrum of HLX-1 in Outburst
PI: Farrell
Abstract: HLX-1 currently provides the strongest evidence for the existence of
intermediate mass black holes. Previous observations with XMM and an
ongoing monitoring campaign with Swift have shown that it undergoes
similar spectral state transitions to stellar mass black hole
binaries, with large-scale flux variability by a factor of ~100 over
timescales of weeks to months. Our most recent Swift observation on
August 29th found that it has re-brightened and is currently at
Lx~1.3E42 erg/s, compared to Lx~3E40 erg/s only 3 weeks prior to this.
The spectrum also appears to be dominated by a soft thermal component.
We propose to observe this source with Chandra so as to constrain the
spectrum and luminosity and to search for variability that has been
detected in other states. We will thus be able to test for the
presence of a hard tail in the current spectrum, whether HLX-1 follows
the same Lx-Tin relationship as other ULXs, and whether the nH is
variable (related to outflows).

Sequence Number: 401145

Title : Measuring the spin of the black hole Cygnus X-1
PI: McClintock
Abstract: We are nearing completion of a paper on the spin of Cyg X-1. We
determine the spin by fitting the thermal accretion-disk component to
our fully relativistic disk model, while carefully modeling the
nonthermal component of emission. In this work, we have exhaustively
searched the HEASARC archives (over all time and all missions) for
useful spectra. Remarkably, there is only one suitable broadband
spectrum (a simultaneous observation by ASCA and RXTE made in 1999)
that allows us to constrain the power-law component. There is just
this single spectrum because Cyg X-1 is rarely in the required soft
state and because it has only rarely been observed with detectors
spanning the required energy interval (~1-30 keV). Cyg X-1 has just
entered the soft state. We propose to obtain 3 Chandra observations
(HETG; TE mode; 6 ks each) and will apply for simultaneous RXTE/PCA
coverage. We seek 3 observations because the quality of the soft
varies dramatically (see the references above).

Sequence Number: 401144

Sequence Number: 501371

Title : The first 'non-magnetar' soft gamma repeater
PI: Rea
Abstract: On 2009 June 5 two SGR-like bursts were emitted by a new SGR, SGR
0418+5729 (Esposito et al. 2010, MNRAS, 405, 1787), having a 9.1s spin
period. The outburst faded by a factor of ∼10 in about 200 days
when it became Sun constrained for many X-ray satellites. Although
this SGR showed all the characteristics of SGRs' outbursts, a
phase-coherent timing solution over the first ∼200 d yielded no
evidence for any pdot, implying a 3σ u.l. on the B-field of <1.5
10^{13} G. This is the lowest magnetic field ever observed for a
magnetar, and the first lower than the electron critical B (~4x10^{13}
G), posing serious problems to the magnetar model. The source became
visible again by Swift (and Chandra) a few days ago. Swift detected
the SGR (8sigma) but it showed a very low flux
(1.3x10^{-13}erg/s/cm2), too low to measure a periodicity with XRT. We
ask for an ACIS-S observation of 30ks within 15 days to have a final
detection of the B-field of this low magnetic field magnetar.

Sequence Number: 401141

Title : X-ray spectroscopy of Cir X-1 through its transition to an
exceptionally hard X-ray state
PI: D'A
Abstract: Following a long period of X-ray quiescence Cir X-1 shown a new X-ray
re-brightening from May 2010 (Atel #2608).The source has shown a
decline of its flux where the X-ray emission become dominated by
extended structures (Atel #2650, Atel #2674).A strong radio
re-brightening of the source was detected on June 24 by ATCA (Atel
#2699). The latest X-ray spectrum observed with Swift XRT (MJD
55373.47, June 26th) revealed an unusually hard spectrum (Gamma ~ 1
power-law) and absorbed by a local absorber (N_h 10^24 cm^-2).The
spectrum also shows an intense and broadened iron line at 6.4 keV
(eqw. width ~ 200 eV). We request a 20 ks Chandra/HETGS observation of
this source with these aims: to resolve the line emitting plasma and
the origin of the broadened iron line and to define the role and the
physical parameters of the plasma constituting the base of the jet
observed in the radio band.

Sequence Number: 900939

Title : The Chandra Deep Field-South Survey: An Ultradeep Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary Observation to increase the exposure on the
Chandra Deep Field South from around 2 Msecs to around 4 Msecs.

Sequence Number: 900939

Sequence Number: 501369

Title : Chandra Observations of the ultra-dark GRB 100615A
PI: Levan
Abstract: A fraction of gamma-ray bursts are dark in the optical and even in the
nIR. These can be localised only using X-ray afterglows. This sample
probably includes bursts in highly obscured, extreme star forming
regions, and may originate in decidedly different environments from
optically bright bursts. Unfortunately, Swift X-ray positions are not
sufficiently precise to allow unambiguous identification of the host
galaxies, while sub-arcsecond positions from Chandra do allow for this
identification. With position in hand we can search for the host
galaxy, study its luminosity and morphology, obtain its redshift and
measure the location of the burst upon it -- these observations can
then be compared to those of optically bright bursts to derive
meaningful constraints on the burst environment. All of this
subsequent science is enabled by a modest (15 ks) Chandra
observation.

Sequence Number: 900939

Sequence Number: 900938

Sequence Number: 501368

Sequence Number: 900938

Sequence Number: 900936

Sequence Number: 300283

Title : The maturing of the remarkable supersoft source KT Eri
PI: Drake
Abstract: LETGS observations of KT Eri in the early SSS phase revealed dramatic
changes in C and N absorption with time that probe their abundances in
the ejected envelope and the depth-dependent nucleosynthesis of the
central engine during the blast. Now the SSS has matured, the ejected
envelope will have dissipated, and a new observation will probe the
abundances in the radiatively-driven wind and evelope and the
steady-state CN-processing. Chandra is by far best suited for this
very soft, low NH target whose spectrum extends longward of 50A. A
continuous Chandra observation will have additional value for testing
a tentative Swift detection of a 35s periodicity possibly caused by
pulsations of the white dwarf.

Sequence Number: 900937

Sequence Number: 900936

Sequence Number: 401138

Title : X-ray Column Density Towards The Low Mass X-ray Binary 4U 1608-522
PI: Ozel
Abstract: We request a 25 ks observation of the transient low-mass X-ray binary
4U 1608-52 with Chandra HETG to measure the interstellar extinction
towards the source using absorption edges in its spectrum. 4U 1608-52
is one of our gold standard sources for the neutron star mass-radius
measurements. The column density is used to determine the distance to
the source employing a technique that makes use of red clump stars in
the field of view of the source. However, so far, only a 5ks XMM
observation has been available to measure the column density, which
results in large distance errors. Chandra observations will greatly
reduce this uncertainty by pinning down the column density with
grating observations, which, in turn, will significantly reduce the
uncertainties in the neutron star mass and radius.

Sequence Number: 900936

Sequence Number: 300277

Title : U Sco in outburst
PI: Orio
Abstract: U Sco is a VERY peculiar recurrent nova, that does not have a giant
secondary and yet is very fast. The "speed" (of ejecta and light
curve) indicates an extremely massive white dwarf. The secondary has
lost a large part of its envelope and is extremely helium enriched,
indicating an evolved system altogether - one that may be close to a
type Ia supernova explosion! X-rays are the only window to the
extremely hot underlying white dwarf and in the case of U Sco, it
would be extremely interesting to find out whether it is a massive
white dwarf, and whether it is a CO or a Ne-O-Mg white dwarf. In a new
paper on the 2006 grating observations of RS Ophiuchi, E. Behar and I
have found overwhelming evidence that RS Oph hosts a Ne-O-Mg whire
dwarf, hence is not a type I a supernova candidate. This is based on
spectral lines that appeared only for a short amount of time and have
never been observed in astronomy before (we have laboratory
confirmation).

Sequence Number: 300276

Title : The bright super-supersoft souce phase of KT Eri
PI: Drake
Abstract: Further Chandra LETGS observations will take advantage of the rare
100+ Swift XRT count/s nova, KT Eri, to probe the nature of the
explosion through the properties of the expanding enveloped of the
SSS. KT Eri is a high galactic latitude (low NH) nova that exploded on
2009 November 14. The SSS phase was detected at 13 count/s in ongoing
Swift monitoring on 2010 January 19 (day 65.7), during which the soft
X-ray flux with BB kT~20eV varied dramatically by factors of ~20 on a
timescale of ~3 hours, similar to the SSS phases of RS Oph and V458
Vul. The Swift count rate had risen steadily to 150 count/s by January
25, accompanied by variability of a factor of 2-3. A 15ks Chandra
LETGS observation obtained on January 23-24 showed a highly detailed
spectrum with numerous prominent broadened absorption features and a
clear P Cygni profile in N VI. Chandra is by far best suited for this
very soft, low NH target whose spectrum extends longward of 50A.

Sequence Number: 300275

Sequence Number: 300274

Title : The early SSS phase of the Classical Nova KT Eri
PI: Ness
Abstract: All novae are thought to evolve through a SuperSoft (SSS) phase,
during which the hot (kT~20-50 eV) surface of the nuclear-burning
white dwarf is visible. However, novae evolve rapidly and only 3 novae
have been observed at high spectral resolution in X-rays during the
SSS phase. Our ongoing Swift monitoring of novae in outburst has
discovered that high-amplitude variations can occur in the SSS phase
(eg RS Oph, V458 Vul). The driver is unknown, and more observations
are needed. These oscillations were first seen during 2003 Chandra
observations of V4743 Sgr where a bright SSS (40 LETG cps)
transitioned into a 0.6 cps photoionized/-excited emission line
spectrum. The nova KT Eri has entered its SSS phase (today), and Swift
is seeing high amplitude flux oscillations. A Chandra LETGS
observation will probe the spectral properties of the SSS phase at
high spectral and temporal resolution. Since all novae have behaved
differently in X-rays, a larger sample is needed.

Sequence Number: 702317

Title : Gravitationally lensed quasar Q0957+561AB in outburst
PI: Goicoechea
Abstract: Q0957+561AB consists of two images, A and B, separated by 6 arcsec, of
a single quasar at z = 1.41. Optical monitoring of the lensed quasar
showed that the g-band flux of the leading image A increased 30% over
about 130 days. Taking the time delay into account, it is expected a
similar g-band brightening of the trailing image B in the first
semester of 2010 (see ATel#2228 on 5 Oct 2009). Thus, a
multiwavelength follow-up of this system over 2010 offers a unique
opportunity to study the involved mechanism of variability. There is
clear evidence that UV/optical variability of local AGN on restframe
timescales < 100 d is mainly driven by X-ray/EUV fluctuations that are
generated close to the accretion disc axis (reverberation scenario).
Chandra observations of Q0957+561B will allow us to check if the
expected optical event is triggered (and thus preceded) by an X-ray
flare. We want to confirm the reverberation scenario in a non-local (z
> 1) AGN for first time.

Sequence Number: 702316

Sequence Number: 702315

Sequence Number: 702314

Sequence Number: 702313

Sequence Number: 702312

Sequence Number: 702311

Sequence Number: 702310

Sequence Number: 702309

Sequence Number: 702308

Sequence Number: 702307

Sequence Number: 702306

Sequence Number: 401137

Title : Chandra High Resolution Spectroscopy of the Be X-Ray binary A0535+262
PI: Reynolds
Abstract: We propose to observe the Be X-ray pulsar binary 1A 0535+262 with
Chandra HETGS for 20 ks. This observations will allow us to
investigate: 1) High M_dot accretion onto a NS: These observations
will allow us to probe accretion at a high fraction of the Eddington
luminosity onto a neutron star with an accurately constrained B-field
(4e12 -- Cyclotron lines) and spin period (X-ray pulsations). 2) Disk
winds from accreting compact objects: Miller et al. (2008) have
previously obtained HETGS spectra of the black hole transient GRO
J1655-40; while Ueda et al. (2004) have obtained HETGS spectra of the
Z-source GX13+1. In both cases numerous wind absorption lines are
observed. 3) Relativistic accretion disk emission lines: Cackett et
al. (2009) have observed relativistic Fe emission from a sample of
accreting neutron star LMXBs (Z, Atoll, MSP) providing constraints on
the radius of the neutron star. This will be the definitive Chandra
observation of a Be X-ray binary.

Sequence Number: 401137

Sequence Number: 900936

Sequence Number: 900939

Sequence Number: 900938

Sequence Number: 900937

Sequence Number: 900936

Sequence Number: 200656

Title : X-ray Emission from V838 Mon: Stellar Merger or Ejecta-Companion
Interactions?
PI: Kastner
Abstract: The nature of the infamous 2002 outburst of V838 Mon (Bond 2007;
Tylenda et al. 2009 [T09]) remains uncertain. No nova-like "hot phase"
was observed and the presence of a B3V companion and a small cluster
implies the system is too young to harbor an accreting white dwarf.
Among the leading models for the outburst is that of a stellar merger
(Soker & Tylenda 2007 [ST07]). The merger product should become
magnetically active well after outburst (ST07), suggesting that V838
Mon should make a delayed appearance as an X-ray source. Indeed, V838
Mon went undetected by CXO in 2003 (Orio et al 2003), but when we
reobserved the object in 2008 with XMM we detected a luminous X-ray
source very near its position (Antonini et al 2009). This source may
be the spun-up merger remnant. However, V838Mon s ejecta had just
engulfed its companion at the time of our XMM observation (T09). Hence
the XMM source might be due instead to interactions between V838 Mon s
ejecta and its companion.

Sequence Number: 401125

Title : A precise position for the intermediate mass black hole candidate in
ESO 243-49
PI: Farrell
Abstract: We recently identified a ULX that provides the strongest evidence for
the existence of intermediate mass black holes (Farrell et al., 2009,
Nature, 460, 73). Previous observations with XMM and Swift gave
incompatible positions at the 1 sigma level. We obtained a 1 ks
Chandra DDT observation on 07/04/09 to resolve this discrepancy. The
ULX was not detected, so has dropped by a factor >6 in flux. By
analogy with stellar mass black holes, this might indicate a
transition into a low/hard state; such a transition has never been
observed so far from any ULX. Triggered by this result and the unique
properties of the source, we are currently preparing requests for deep
ground and space-based telescope observations, whose analysis will
require a high precision that only Chandra can provide. Even a
non-detection would be a highly significant result, as it could
indicate the ULX has undergone a transition into the low/hard state; a
phenomenon commonly observed in Galactic X-ray binaries.

Sequence Number: 401124

Title : Following the Decay of NGC 6440 X-2
PI: Heinke
Abstract: On July 28-29, our GO Chandra image of NGC 6440 discovered a 2nd
transient LMXB in outburst in the globular cluster NGC 6440 (Atel
2139). RXTE/PCA saw indications of flaring at 0.7 Hz, similar to 1 Hz
flaring from SAX J1808, which indicated propeller instabilities in the
flow (Patruno+09). We request one 5-ksec ACIS-S observation of NGC
6440 by August 14 to determine whether this transient has returned to
full quiescence (<1e31) or undergoes accretion instabilities at low
(Lx~5e32) levels, as SAX J1808 did (Campana+08). 5 ksec will give >10
cts for Lx(0.5-10)>3e32 ergs/s (either BB @0.2 keV, or PL @index~2.2
as seen by Swift for 6440 X-2).

Sequence Number: 501174

Title : Searching for the X-ray counterpart to J1622-49
PI: Rea
Abstract: A new neutron star has been recently discovered during the Parkes High
Time Resolution Universe Survey. Its radio emission is highly variable
reaching strong luminosities (up to ~35mJy). We ask for a 20ks Chandra
ACIS-I observation to characterize its X-ray counterpart, in search
for a similarly variable X-ray emission.

Sequence Number: 701973

Title : The nature of the highly-variable X-ray galaxy KUG 1259+280
PI: Watson
Abstract: We have discovered a bright, strongly variable 2XMM X-ray source which
is <2" from the nucleus of a nearby (D~100 Mpc) post-starburst galaxy
KUG 1259+280. In the XMM-Newton discovery observation the source shows
a strong flare lasting 2500 sec with a factor ~8 flux increase on a
timescale <1000 sec. Even more remarkably the X-ray spectrum is
characterized by an unprecedently soft continuum well-fit with a
power-law model with gamma=4.7. The short-timescale variability,
luminosity (Lx~3E41 erg/sec) and location close to the nucleus
suggests an NLS1 AGN, but only weak, narrow Balmer lines (consistent
with starburst) are detected in the SDSS spectrum once host galaxy
contamination is removed. Proposed Chandra observation will locate the
X-ray source to ~0.2 arcsec (~100 pc) to see if it is truly coincident
with the nucleus - importantly if it is off-nucleus this would make it
an ULX. Observation will also check for faint extended X-ray emission
and constrain variability/spectrum.

Sequence Number: 401066

Title : A precise position for the intermediate mass black hole candidate in
ESO 243-49
PI: Farrell
Abstract: While investigating the 2XMM catalogue, we identified a new ULX in the
galaxy ESO 243-49 with an unabsorbed 0.2-10 keV Lx = 1.1E42 erg/s. A
follow-up DDT observation with XMM found the spectrum had changed
significantly, ruling out multiple low-luminosity sources. The Lx is
almost an order of magnitude greater than the previous record holder,
which when taken with the steep power-law spectrum and lack of radio
emission rules out beaming. This ULX, with a conservative mass lower
limit of ~500 Msun, provides the strongest evidence for the existence
of intermediate mass black holes (Farrell et al., 2009, Nature, in
press). This object is unique, puzzling and worth following-up given
the significance of the results. We will begin monitoring this ULX
with Swift in August to search for variability. Any significant
changes in flux/spectrum will trigger requests for deep observations
with ground based telescopes. Before such observations can take place
a high precision position is required.

Sequence Number: 401065

Title : Simultaneous Chandra/ATCA observation of GRO J1655-40 in quiescence
PI: Gallo
Abstract: We have recently been awarded a very deep (12 hr) radio observation of
the quiescent X-ray binary GRO J1655-40 with the newly refurbished
Australia Telescope Compact Array (ATCA) on June 7. The goal of this
observation is to probe jet formation at the lowest possible mass
accretion rates. Beside A0620-00, which was observed simultaneously by
the VLA and Chandra in 2005 (Gallo et al. 2006, MNRAS, 370, 1351),
there is only one other quiescent black-hole system whose properties
enable us to probe jet formation at such low accretion rates, and that
is GRO J1655-40. As well as anchoring the radio:X-ray correlation at
the lowest luminosities, we should be also able to detect the radio
spectrum of a truly quiescent source for the first time. In turn, this
will allow us to compare the broadband spectral energy distribution of
a quiescent stellar mass black hole to that of the quiescent 4E+6
solar mass black hole in the Galactic Center.

Sequence Number: 200569

Title : X-ray emission from the pre-main sequence star ZCMa during a
FUOri-type outburst
PI: Stelzer
Abstract: We propose for the first X-ray spectrum of an FUOri object during
outburst. The FUOR phenomenon is associated with a sudden increase of
the accretion rate in some pre-main sequence (PMS) stars, possibly due
to changes in the magnetic field. In the first X-ray survey of FUORs
Skinner et al. (2007) have detected two of four targets. None of them
was in outburst at the time. The typical two-temperature spectrum of a
PMS star requires in the case of FUOri different absorptions for the
soft and hard components (Skinner et al. 2006). Our target ZCMa is a
young F-type FUOR. In Feb 2008 ZCMa started its so far largest
outburst, with a further enhancement ~2 weeks ago. In May 2008 we have
detected its magnetic field. Now we aim at an X-ray detection of ZCMa
in its `super-outburst'.

Sequence Number: 200568

Title : The current X-ray status of the planet bearing host star 51 Peg
PI: Schmitt
Abstract: In a 50 ksec XMM pointing we found a X-ray flux drop of >20 (compared
to ROSAT) for 51 Peg, the most famous planet-bearing host star. 51 Peg
is of very low activity and its chromospheric flux has been stable
over many years. A dramatic (downward) change in soft X-ray flux has
never been observed before in any star with the possible exception of
Alpha Cen. It is important to check how long this extremely low
activity state of 51 Peg persists. The X-ray surface flux derived from
the XMM lies more than one order of magnitude below expectation. A
possible solution is a coronal temperature change. An HRC pointing
with its larger low energy sensitivity will show if there is
undetected flux in the 0.1-0.2 keV band or if 51 Peg's corona has
almost completely disappeared from the X-ray world.

Sequence Number: 200568

Sequence Number: 401051

Title : Is XTE J1701-407 Extended?
PI: Kaplan
Abstract: We recently observed the neutron star X-ray transient XTE J1701-407
with Chandra, using 1 ks of ACIS-S data for localization. However, the
Chandra data do not show a point source. Instead the source appears
extended over ~6 arcsec. We have investigated the data, consulting
with experts both at MIT and SAO, and cannot ascribe the data to
purely instrumental effects (aspect errors or pileup). The extended
X-ray emission could come from an outflow or a dust scattering halo -
both very interesting and rare phenomena. Jets allow detailed
calorimetry of the outbursts, while scattering halos lead to geometric
distances. We request a 5 ks ACIS-S subarray observation to
definitively assess the morphology, trying to discriminate between
these scenarios before the target fades into quiescence.

Sequence Number: 501152

Title : The X-ray light-curve of GRB 080307
PI: Page
Abstract: The canonical X-ray light-curve with a steep-plateau-normal decay, has
been attributed to continued energy injection; when this input ceases,
we see the steepening to the standard decay (alpha~1.3). In the case
of GRB 080307, the onset of the plateau was unusually late and,
uniquely, the decay was still continuing with a slope of <1 more than
a month after the burst. If intrinsic, this slow decay would place
severe constraints on the proposed injection model, requiring the
engine to be active for a very long time. Deep Gemini imaging reveals
a second optical source within the XRT error circle, which is a
possible source of contamination. Chandra's PSF and sensitivity will
allow us to test whether there is any contamination from this nearby
source and whether the decay has broken.

Sequence Number: 401050

Title : V Puppis: A black hole triple?
PI: Maccarone
Abstract: The nearby eclipsing binary VPup has recently been suggested on the
basis of eclipse timing residuals to have a third body with a ~5 year
orbital period and a mass of ~10 solar masses, but for which there is
no spectroscopic evidence, making it the only strong candidate for
having a black hole in a wide binary in the Galaxy. At a distance of
300 pc, this object can be studied in great detail, even if it is
extremely faint, and is the only black hole candidate with a Hipparcos
parallax distance. Past observatories showed variable X-ray emission
from this region at a level which was reasonable for Bondi accretion
from the stellar wind of the B giant in the VPup. We have recently
made ATCA observations of this region and need X-ray observations as
well, to compare the two fluxes or upper limits to determine whether
it is reasonable for such a flux ratio to come from a stellar mass
black hole, and to ensure that the past X-ray emission really is from
VPup, rather than a nearby object.

Sequence Number: 400934

Title : Locating the Ultraluminous Supersoft X-ray Source in NGC300
PI: Kong
Abstract: We propose to obtain the first Chandra image of the nearest very
luminous (Lx=1e38-1e39 erg/s) recurrent supersoft X-ray source (SSS)
currently in outburst. The source, located in NGC300, has a 5.4-hr
period and is ultraluminous in the high state. In AO-7, we obtained a
Chandra HRC-I observation to locate the position in order to search
for the optical counterpart in archival HST and VLT images. However,
the source was off with a 99% upper limit of 3.5e37 erg/s (ATel#1560).
NGC300 was observed with Swift on 2008 5/20, 6/4, and 6/19. The SSS
was clearly detected with XRT in all observations and all the source
photons are from below 0.7 keV, consistent with a SSS. The 0.2-2 keV
unabsorbed luminosity is about 1.5-2e38 erg/s (ATel#1560). If the
companion can be identified, we can set a strong constraint on the
donor and conclude whether the compact object is an IMBH. It would
also provide important information about the formation of SSS in a
black hole binary system.

Sequence Number: 400933

Title : The cold neutron star in the long-duration transient AX J1754.2-2754
PI: Keek
Abstract: As written in Atel#1575, J1754j went to quiescence after a long
outburst. The source is an ultra-compact X-ray binary. The long
outburst duration and ultra-compact nature make this source resemble
H1905+000. The current Chandra non-detection, based on a 2 ks-long
observation, shows that J1754 is very faint already given that the
long outburst duration facilitates a high neutron star crust
temperature. The low flux and the relatively high N_H forego
triggering the Wijnands et al. ToO (which is based on measuring
neutron star X-ray spectra). Instead, we propose to obtain one 30 ks
observation to search for J1754 in quiescence. In 30 ks we would reach
a flux limit of ~5E-15 erg cm-2 s-1, yielding a luminosity limit of
5E31 erg/s. A non-detection would make J1754 the second UCXB to be
very cold (after H1905) suggesting that the UC nature and hence the
composition of the accreted material is important for setting the NS
temperature and or the cooling rate.

Sequence Number: 501018

Title : An Unexpected Re-Brightening in SHB 080503: Afterglow or
mini-Supernova, 2nd Epoch
PI: Butler
Abstract: Gaining a deep understanding of the origin and nature of Short
(duration) Hard (spectrum) Gamma-ray Bursts (SHBs) is one of the last
frontiers of GRB research. We can now say almost for certain that the
progenitors of SHBs are different from those of Long-Soft GRBs (LSBs).
This is based almost entirely on observations of the host galaxies of
SHBs, which seem to be an older population than the hosts of LSBs:
whereas the 50+ hosts of LSBs appear to be underluminous star bursts,
and a handful of the bursts themselves have been directly associated
with supernova (SN) explosions. SHB hosts span the range from giant
elliptical to faint blue galaxies. A multi-wavelength campaign is
critical to ameliorate the large theoretical uncertainty as to what
types of progenitor systems --- a possible ``mini-SN'' (Li \&
Paczynski 1998) from a compact object mergers or binary WD merger
(Levan et al. 2006) --- are at the origin of SHBs.

Sequence Number: 501017

Title : An Unexpected Re-Brightening in SHB 080503: Afterglow or
mini-Supernova
PI: Butler
Abstract: Gaining a deep understanding of the origin and nature of Short
(duration) Hard (spectrum) Gamma-ray Bursts (SHBs) is one of the last
frontiers of GRB research. We can now say almost for certain that the
progenitors of SHBs are different from those of Long-Soft GRBs (LSBs).
This is based almost entirely on observations of the host galaxies of
SHBs, which seem to be an older population than the hosts of LSBs:
whereas the 50+ hosts of LSBs appear to be underluminous star bursts,
and a handful of the bursts themselves have been directly associated
with supernova (SN) explosions. SHB hosts span the range from giant
elliptical to faint blue galaxies. A multi-wavelength campaign is
critical to ameliorate the large theoretical uncertainty as to what
types of progenitor systems --- a possible ``mini-SN'' (Li \&
Paczynski 1998) from a compact object mergers or binary WD merger
(Levan et al. 2006) --- are at the origin of SHBs.

Sequence Number: 400932

Title : Chandra follow up of XTE J1719-291
PI: Sala
Abstract: XTE J1719-291 is a new, faint X-ray transient, discovered with
RXTE/PCA on March 21 (ATel#1442). PCA monitoring indicated an initial
rise followed by a delcine. Swift/XRT follow up on 30 March and April
3 provided the position with an uncertainty of 3.8 arcsec and
confirmed the decline (ATel#1451,#1467). The XRT spectrum was fit with
an absorbed powerlaw with nH=6e21cm-2 and a photon index of 3. A more
recent Swift observation on April 9 showed a re-brightening by a
factor 10 and a hardening of the spectrum (ATel#1467), with a photon
index of 2.5 and a 2-10 keV absorbed flux of 1.4e-11 erg/cm2/s. There
are no known objects in Simbad or ROSAT catalogues within the XRT
error circle. To identify the IR counterpart, we observed XTE J1719 on
April 11 in 7 bands (grizJHK) with GROND at the MPI/ESO 2.2m telescope
at La Silla. We find 13 near-infrared sources in the XRT error circle.
The transient properties are unusual, so it's unclear what kind of NIR
variability is to be expected.

Sequence Number: 701771

Title : Chandra observation of a flaring galaxy with strong optical
emission-line light echo
PI: Komossa
Abstract: We have discovered among SDSS-DR6, in Dec. 2007, a galaxy which is
unique in showing super-strong high-ionization iron lines and very
unusual double-peaked Balmer lines which are fading away, but have not
yet disappeared. The high degree of line ionization implies that we
see the light-echo of an (unobserved) EUV-X-ray flare. We have
confirmed, with optical ToO photometry on Jan. 1, 2008 the low-energy
tail of this flare in the optical and NIR. Only a few X-ray flaring
galaxies are known. This is the first time we have seen such a broad
line and continuum response. With Chandra, we will for the first time
detect the actual X-rays from this flare, characterize the X-ray
emission, locate the flare within 1 kpc of the nucleus, and test the
favored scenario - tidal disruption of a star - before the flare has
faded away. Depending on the measured source's X-ray brightness, we
will then consider X-ray monitoring to map the emission-line changes
in response to the X-ray fading.

Sequence Number: 400931

Title : A rare transient in M81: a merger event?
PI: Jonker
Abstract: A recently discovered optical transient (OT) in M81 (atel #1330) can
not be explained by a known transient event, it is a very good merger
candidate (NS-NS, BH-NS). Distinguishing properties are: decay rate is
too fast for a NOVA, optical brightness is too low for a SN (MV=-7.3),
the K-band magnitude and NIR colors rule out a foreground flaring
M-dwarf, the source is too bright for an transient X-ray binary. We
searched the Chandra archive for the presence of an X-ray source. None
was found even after stacking all the ACIS data. A transient X-ray
source was observed on 2000-05-07 in Chandra OBS ID 735 close to the
position of the OT. However, the distance to the position of the OT
was 2.8 arcsec which is too much for the two events to come from the
same source. The optical decay time matches the predicted decay time
for a merger event (Sylvestre 2003). If this OT is a merger event,
X-rays are predicted to be emitted due to either fall back or
radio-active decay of ejected material.

Sequence Number: 501014

Title : Chandra observations of a nearby supernova
PI: Roelofs
Abstract: We propose Chandra observations of the nearby type-Ia supernova
SN2007on to characterize its X-ray emission, which will help us
constrain the nature of the progenitor. We ask for an initial 40ks
which will enable us to put useful constraints on its X-ray flux.

Sequence Number: 501014

Sequence Number: 200526

Title : The physics of flares in young stellar objects
PI: Micela
Abstract: Flares are the most extreme manifestation of stellar activity.
Magnetic reconnection produces fast electrons that hit the stellar
surface to produce chromospheric material evaporation. Non-thermal
heating shows up as impulsive flares in optical and hard X-rays, and
evaporation as longer soft X-ray flares. Multi-band observations
covering thermal and non-thermal components are essential to
understand the physics of flaring. The CoRoT space telescope will
continuously observe the star forming region NGC2264 for 20 days in
March 2008 in the optical with unprecedented photometric precision and
with a temporal resolution of 10s of sec, ideal for the detection of
impulsive events. We ask for two 100ksec observations in the two most
populated cluster regions during the CoRoT observation to
simultaneously study the non-thermal (CoRoT) and the thermal (Chandra)
components of flares. 100s of flaring sources have already been
detected in a single ACIS field in NGC2264 (Flaccomio et al. 2006).

Sequence Number: 200526

Sequence Number: 100071

Title : Utilizing the exceptional outburst of Comet 17P/Holmes for probing the
solar wind at 2.5 AU
PI: Dennerl
Abstract: We propose to utilize the extreme outburst of Comet 17P/Holmes for
novel X-ray studies with Chandra. Due to the nature of the outburst,
we expect the gas coma to be collisionally thick to charge exchange,
providing the maximum surface brightness. At a heliocentric distance
of 2.5 AU, 1.0 AU more than any other comet observed with Chandra, it
will not only allow us to probe the solar wind at a far distance, but
it will also provide an unprecedented viewing geometry - we will see
the comet from almost the direction as the incident solar wind. Thus,
by utilizing the high spatial resolution of Chandra, it should be
possible to explore the spectral evolution across the face of the
coma. The ecliptic latitude of the comet is 19 deg, so that there is a
possibility that this will become the first Chandra observation of a
comet which is interacting with the polar solar wind or in the
transition zone between the ecliptic and polar winds.

Sequence Number: 100071

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 400928

Title : Which M15 X-ray Source Brightened?
PI: Heinke
Abstract: We have recently discovered, in archival data, a very faint X-ray
transient in M15 (2004 and 1994 outbursts at ~5e33 ergs/s), in
addition to the two known bright LMXBs. We have just become aware that
the RXTE ASM has recently (June-July) registered an outburst from M15
(=X2127+119), with countrates reaching 4 times normal. 3-4 smaller
outbursts have been seen by RXTE, but this is the brightest yet seen.
Both M15 persistent LMXBs show stable mass transfer. We suspect that
the recent outburst may be due to a third source, possibly the newly
identified transient, or perhaps another source. We request a short
10-ksec HRC-I observation of M15 sometime over the next 10 days to
identify if another X-ray source, besides the two bright LMXBs, is
responsible for the recent brightening of M15. This will give at least
5 counts from all sources with Lx(0.5-10)>2.6e32 ergs/s (for photon
index 1.7).

Sequence Number: 501009

Title : A radio and X-ray study of Type Ic SN2007gr at < 10 Mpc
PI: Soderberg
Abstract: The new Type Ic SN2007gr at just 10 Mpc was spectroscopically
identified on Aug 16 2007 at an estimated age of a few days since
explosion. Our radio follow-up on Aug 17 shows a radio transient
coincident with the optical position. Simultaneous radio (synchrotron)
and X-ray (synchrotron,thermal,and/or IC) observations of SNe Ibc
trace the interaction of the fastest ejecta with the circumstellar
material and have been limited to just a handful of events to date.
The combination of radio and X-ray data breaks model degeneracies and
enables the parameters of the fastest ejecta to be revealed.
Extrapolating the optically thin radio emission as nu^-0.7 to the
X-ray band we expect at a count rate of roughly 0.0005 cps. We
therefore request 20 ksec of DDT within 1-2 weeks for our radio/X-ray
study of this very nearby SN.

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 400691

Title : RFO with Chandra of the newly discovered Millisecond X-ray Pulsar
(MsXP) SWIFT J1756.9-2508
PI: Di Salvo
Abstract: According to the recycling scenario MsXPs are the progenitors of radio
ms pulsars.The recent discovery of the 5.5ms pulsar in the X-ray
transient SWIFT J1756.9-2508(ATEL #1108)brought to 8 the number of
sources of this class.Timing techniques applied to high temporal
resolution data allows the direct measurement of the rotational
behavior of the compact object under the effect of accretion,leading
to an unique opportunity to answer to the long lasting dispute about
accretion models for fast rotators(Burderi 2006,ApJL,653,133;Burderi
2007,ApJ,657,961(BD);Papitto 2007,MNRAS,375,971).However timing
analysis is able to produce reliable results only when an accurate
position of the source is known(BD).The excellent Chandra spatial
resolution will provide an unique accuracy on this key
parameter(Krauss 2005,ApJ,627,910(KR))to further investigate the
rotational behavior of these objects.Chandra will also give us the
possibility to study a high energy resolution spectrum of this
source.

Sequence Number: 400690

Title : Observing flaring activity in the new source SWIFT J195509.6+261406
PI: KANBACH
Abstract: SWIFT/BAT triggered on a new source on 10 June, 2007 20:52:26 UTC
(GCN# 6489, Pagani et al.). The reported position was promptly
observed in optical light and, after some delay, with the XRT. Bright
short optical outbursts (10s timescales, amplitudes >3 mag) were
discovered in the first hour after the trigger and again during the
night June 11-12, 2007 (GCN# 6492,6508, Stefanescu et al.). SWIFT/XRT
confirmed the position of the optical counterpart and the flaring
behaviour (amplitudes up to 25 mCrab). We propose to perform CXO-HETG
spectroscopy of the source to determine the emission process through
the spectrum, and thus the nature of this object. It could be a fast,
giant X-ray transient, SGR or AXP, or a thermonuclear X-ray burster.

Sequence Number: 400689

Title : X-ray jets in CirX-1
PI: Jonker
Abstract: CirX-1 is a neutron star (Tennant et al 1986a,b). The X-ray and radio
flux of CirX-1 have gradually decayed over the last few years.
Recently the radio flux has increased dramatically (ATel 985). The
source has returned to the low X-ray-flux high radio-flux state as
found in the 1970-80ties. On March 6 Fender observed a radio jet using
ATCA at 2" from the core. Interestingly, the position angle of the
radio jet has changed. The large radio flares suggest that major
ejection events take place. We propose a 50 ksec HRC-I observation to
take advantage of the current favorable source/jet count rate ratio to
search for an X-ray counterpart to the new radio jet emission. We
assumed that the X-ray flux and spectrum of a jet is the same as the
X-ray jet observed in XTE J1550-564. For the X-ray flux of CirX-1 we
took the value from our SWIFT-XRT ToO observation of March 19. We
simulated with ChaRT/marx that even a jet placed at a distance of
0.75" is detectable.

Sequence Number: 400688

Sequence Number: 600649

Title : Constraining the Geometry and Energetics of the Exceptionally
Energetic GRB070125
PI: Frail
Abstract: The IPN and Swift-localized GRB070125, the brightest radio afterglow
seen in almost four years, exhibits a steep spectrum from GHz
frequencies up to ~1 mm, indicating a dense local environment (n >~
100 cm^-3) and an extreme isotropic-equivalent afterglow energy
(~10^54 erg). Depending solely on the angle of collimation (i.e. "jet
opening angle") derived for this burst, it may easily become the
highest-energy release GRB seen to date, straining the capacity of
collapsar models and sounding the death knell for the "standard energy
reservoir" of GRBs (Frail et al., ApJ, 562, 2001). We have an
extensive set of optical and radio data for this burst that show a
likely jet break at t~5 days; at this same epoch, the X-ray afterglow
fades below the detection limit of Swift. We request a single 30-ksec
observation with Chandra to distinguish jet-break from no-break models
for the X-ray emission, and therefore to enable measurement of the
prompt and afterglow energies for this remarkable event.

Sequence Number: 500822

Title : Localization of SN 2005kd
PI: Pooley
Abstract: We propose to observe the Type IIn (narrow emission line) SN 2005kd. A
recent optical spectrum shows it is similar to the extremely X-ray
luminous SN 1988Z (in fact, it has a higher eq. width of H\alpha than
88Z did at a similar epoch). A recent Swift observation detected
emission consistent with the SN at Lx = 1.4e41 erg/s (d=61.5 Mpc).
Because the SN is only 5" from the nucleus of its host galaxy, and
because there may be ULXs also present in the host, we would like to
determine the amount of "contamination" in the Swift emission to the
10% level. In 3ks, we will detect ~75 counts from 05kd, and ~7 counts
from something that's 10% the flux. This will allow a conclusive
association of the Swift source with the SN, as well as provide a
measure of possible contaminating sources. We also plan on proposing
for a deep XMM observation to obtain a high quality spectrum (it will
be visible in a few weeks), and in this case as well, a measure of
contamination will be invaluable.

Sequence Number: 701583

Title : Short Timescale X-ray Variability in the M87 Jet: the TeV connection
PI: Harris
Abstract: The recent interpretation of TeV observations of M87 (Aharonian, 2006
Sci. 314, 1424) hinged on the conventional perception that variability
of a few days requires extremely small emitting volumes which can only
be found close to the nuclear black hole. So in spite of the agreement
in lightcurve peaks (X-ray HST-1 and TeV whole source), the HESS group
argued that the TeV emission originated close to the SMBH rather than
at the distance of HST-1, 200 pc (deproj) from the nucleus. This
proposal requests 8 observations of 5ks each, to measure amplitudes of
X-ray variability of HST-1 and the nucleus for intervals of 3 to 20
days. We already know that HST-1 manifests 2 of the defining
characteristics of blazars: a broad-band intensity flare (factor of
50) and the launching of superluminal radio components. Determination
of which component of M87 has the larger amplitude for day time scale
variability will test the current TeV blazar model and assess the need
for a new blazar paradigm.

Sequence Number: 701582

Sequence Number: 701581

Sequence Number: 701580

Sequence Number: 701579

Sequence Number: 701578

Sequence Number: 701577

Sequence Number: 701576

Sequence Number: 500821

Title : Confirmation of a new Isolated Neutron Star in the ROSAT All Sky
Survey
PI: Rutledge
Abstract: The 7 known X-ray dim isolated neutron stars (INSs) were all
discovered from the ROSAT all-sky survey between 1995 and 1999. We may
have discovered an important one: the first INS in the halo. 1RXS
J1412+7922 is important because: (1) its blackbody spectrum is hotter
than any known INS (235+/-45 eV; compared with 118+/-13 for the next
hottest); (2) its low flux (0.05 PSPC c/s) and high temperature make
it the most distant known INS (8.2 kpc, compared with 2.3 kpc for RX
J0806-4123; the remaining six are <1 kpc); and (3) its high galactic
latitude gives it a galactocentric position (R_c=13.4, z=4.9 kpc) in
the galactic halo. J1412 cannot be powered by accretion (no ISM in the
halo); if cooling, it must be <1e6 yr old, giving a velocity of >4900
km/sec (from the Galactic plane), the highest ever observed.
Otherwise, a cooling time of >1e7 yrs is required, the longest ever
observed.

Sequence Number: 500820

Title : Repudiation or Confirmation of an Enormous Glitch in a Magnetar
PI: Woods
Abstract: On Sep 21, 2006, a bright X-ray burst was recorded (GCN 5581) from the
newly discovered AXP CXO J1647-45. The burst was accompanied by a
large flux increase, spectral hardening, a dramatic pulse profile
change, and a reported glitch of dnu/nu ~1e-4 (ATEL 932) whose
amplitude is unprecedented for any neutron star. Using 4 CXO
observations between 9/27 and 10/28, we have been able to track the
spectral changes, pulse morphology evolution, and provide the first
measurement of the spin-down rate and thus magnetic field strength of
CXO J1647-45 (ATEL 929). Further analysis of all available X-ray data
has brought into question the reality of the reported glitch. The
parameters of this glitch factor heavily into the physical
interpretation of the outburst and in general, our understanding of
the internal structure of magnetars. We are requesting one additional
observation to extend our phase-coherent timing solution to confirm
the measured spin-down rate and better anchor our ephemeris.

Sequence Number: 500817

Title : Accurate position measurement of the Isolated Neutron Star RBS1774
PI: Zane
Abstract: We request a 1ks DDT pointing of the Isolated Neutron Star (INS)
RBS1774, to obtain an accurate determination of the X-ray position.
Position measurements of INSs are of paramount importance for an exact
identification of the optical counterpart: it provides vital
information on the SED, on the cause of the X-ray emission, and, over
a longer term, paves the way to the determination of proper motion and
distance; providing crucial informations on the INS surface
temperature and magnetic field distribution, kick velocity and
energetics, which are still largely unknown. We have recently observed
the RBS1774 field with the VLT, the Magellan telescope and with Keck.
Several sources appear in the XMM error box of the INS and even more
are expected to be detected by deeper VLT images, just requested, that
will push the detection limit down to a V=28. A Chandra HRC-I accurate
position is necessary to reliably determine RBS1774 counterpart.

Sequence Number: 200460

Title : A(nother) Star is Born: the Early Evolution of a Pre-main Sequence
Accretion Burst
PI: Kastner
Abstract: Accretion processes produce X-ray emission in a wide variety of
astrophysical environments, yet the link between pre-main sequence
(PMS) star accretion and X-ray emission remains tenuous at best.
Undoubtedly the most convincing example of accretion-driven PMS X-ray
emission is that of V1647 Ori; Chandra observations obtained over the
(two-year) duration of the optical/IR outburst of this PMS star
revealed that its X-ray flux and hardness closely tracked the dramatic
rise and subsequent decline of its accretion luminosity (Kastner et
al. 2004, Nature, 430, 429 and 2006, ApJ, 648, L43). These results for
V1647 Ori suggest that X-ray emission from erupting low-mass, PMS
stars is diagnostic of the degree of star-disk magnetic field
reorganization during major ("FUor"- or "EXor"-type) accretion events.
Prompt post-outburst observations of additional erupting PMS stars are
required to test this hypothesis.

Sequence Number: 500816

Title : The Extreme Supernova 2006gy
PI: Pooley
Abstract: We propose to observe the Type IIn (narrow emission line) SN 2006gy in
NGC 1260. Its optical spectrum (CBET/IAUC submitted) show it is
similar to the extremely X-ray luminous SN 1988Z, which was observed
at Lx=10^41 erg/s at an age of 6.5 yr. It is unknown what the
early-time (first few weeks to months) Lx of such a SN would be. Past
attempts at early X-ray detections (2005bx, 2005db) have given only
upper limits (but follow-ups have been approved), but the class is
likely not homogenous. The extreme optical luminosity (M_V = -22)
makes this SN stand out even among the IIn's (an already unusual class
of objects). The astrometry will be crucial to resolving the SN from
possible nuclear activity. Two X-ray sources within 2.5 arcmin of
2006gy (found in ObsID 5597) have 2MASS counterparts. They have fluxes
of 5.1e-15 and 2.1e-14 (cgs). Our request of 30 ks is based on
localizing these sources well enough (getting 25-30 cts) to achieve
~<0.2" X-ray/2MASS astrometry.

Sequence Number: 500815

Title : X-Ray Emission from the Type Ib SN 2006jc
PI: Immler
Abstract: An X-ray source is detected at the position of the SN in a 3.4 ks
Swift XRT obs from 2006-10-13 16:10 UT with a flux and lum of
1.0+/-0.4 E-13 ergs/cm/cm/s and 6.7+/-2.7 E39 ergs/s (0.2-10 keV). The
UV-V colors are extremely blue, similar to the X-ray bright SN IIP
2006bp. The Swift UVOT data show that the SN is very bright in the opt
and especially in the UV (ATel 916), likely a result of the shock
interaction with dense CSM, confirming that the X-rays are due to the
SN. Due to the large PSF of the XRT (18 HPD), and an offset of the SN
of 11" W and 7" S of the host galaxy, UGC 4904, XRT data do not allow
us to unambiguously associate the X-ray source with the SN, even at
higher photon statistics. No further Swift obs will be obtained due to
Sun angle constraints. The RASS shows no X-ray source at the position
of the host galaxy. Therefore, the association of the X-ray source
with the SN is strong and the Chandra obs could establish SNe Ib, for
the first time, as X-ray sources.

Sequence Number: 500814

Title : Monitoring a Recovering AXP and Measuring Pdot
PI: Kaspi
Abstract: Anomalous X-ray Pulsar (AXP) outbursts are rare, occuring roughly once
per decade per src, and offer rare opportunities to constrain the
poorly understood physics of magnetars. Recently AXP CXO
164710.2-455216.9 went into outburst and we were granted 3 ToO obs
with CXO. These obs together, via phase-coherent timing, set the best
constraint on the unknown Pdot, which implies magnetic field (3sig)
<2e14 G. This is low for a magnetar but not yet a problem. We request
1 more 25 ks DDT obs of AXP CXO 164710.2-455216.9. This obs will
continue to monitor it back to quiescence to distinguish between
proposed recovery models, and, importantly, if scheduled near Oct 30,
will either detect or put an unprecedented upper limit on Pdot, via
phase connection with previous CXO ToO obs. If no Pdot is detected, we
will constrain B<5e13G (3sig), lower than for any other known magnetar
(lowest known 6e13G), and perplexingly below B measured for some
ordinary, non-magnetar neutron stars.

Sequence Number: 400680

Title : Probing the true nature of the microquasar candidate LS I +61 303
PI: Perez-Torres
Abstract: The radio-emitting x-ray binary LSI +61 303 has been recently detected
at TeV energies. Two scenarios have been proposed to account for this
high-energy emission, namely an accretion/jet mechanism (microquasar),
and an interacting pulsar wind model. We propose to observe LSI +61
303 with Chandra as part of a multi-wavelength campaign that includes
simultaneous observations with MAGIC (gamma-rays), MERLIN (radio), and
Calar Alto (infra-red). (Those observations have been approved for the
nights of the 25 and 26 October 2006.) The proposed observations will
be the first such simultaneous, multiwavelength effort on this object,
and the geometrical, spectral and temporal features of its radio
emission will be studied and correlated with those in the infra-red,
X-ray and, TeV regimes. The results will help to elucidate the true
nature of LS I +61 303 and the acceleration mechanisms that produce
the high energy emission.

Sequence Number: 600607

Title : Accurate X-ray position of a possible >10^41 erg/s ULX: evidence for
an intermediate-mass black hole?
PI: Miniutti
Abstract: We have detected with XMM-Newton an off-nuclear ULX candidate in the
D25 ellipse of a spiral galaxy at 90 Mpc. If at 90 Mpc, its 0.5-10 keV
luminosity is 1.3x10^41 erg/s, the most luminous ULX ever detected.
The probability of it being a background AGN is very low based on
standard logN-logS (<0.7%) and even lower if the minimum X-ray to
Optical flux ratio (>60) is considered. The only available HST image
shows several possible counteparts in the XMM error box. We request a
7ks Chandra ACIS-S exposure to measure the X-ray position with high
accuracy, which will allow us to identify the counterpart (if any)
from HST+Chandra and to organize the optimal follow-up strategy. The
Chandra obs by itself may exclude that the ULX is a background AGN if
the HST counterpart is identified, allowing us to compute a precise
X-ra to Optical ratio which, if > 100 (as for the large majority of
possible counterparts), would exclude the AGN hypothesis.

Sequence Number: 400561

Title : Is PSR B1931+24 the golden source for the accretion regimes testing?
PI: Rea
Abstract: Very recently the discovery of an intermittent radio pulsar was
reported on Science (Kramer et al.2006,astro-ph/0604605). PSR B1931+24
has the surprising peculiarity of being a 813ms radio-pulsar for ~5d
and being radio quiet for the following 25-35d, periodically. The
pulsar spin slows down 50% faster when the pulsar is on than when is
off. The ~30d periodicity and the weird spin-down behaviour of this
radio activity remind what is expected for a pulsar in a binary system
spinning near the equilibrium period in an eccentric ~30d orbit: at
the apastron the low wind accretion rate allows the radio pulsar
regime, while at the periastron the neutron star is radio-quiet
because accreting and emitting in the X-rays. This might be the
linking object between the X-ray binaries and the radio pulsar
binaries, a golden source for finally testing the accretion regimes.

Sequence Number: 100067

Title : An Extremely Close Encounter with the Disintegrating Comet 73P/SW3
PI: Wolk
Abstract: We propose to use the ACIS-S instrument on Chandra to study the X-ray
emission from the fragment B of comet 73P/Schwassmann-Wachmann 3. This
comet is in the act of disintegration and is currently 43 tracked
elements and countless additional pieces as detailed in recent Spitzer
and HST observations. It will also pass closer to the Earth in May
2006 than any comet yet detected in the x-rays. We propose a total of
20 ks observation of fragment B. These data will allow us to spatially
resolve the detailed structure of the interaction zone between the
solar wind and the coma at a spatial resolution of ~75 km, the solar
wind velocity structure in the mass-loading zone at the coma edge. The
interpretation will be simplified relative to previous comets because
ACE/SOHO are almost in front of the comet. We therefore will know the
precise state of the Solar Wind.

Sequence Number: 100066

Sequence Number: 100065

Sequence Number: 100064

Sequence Number: 100063

Sequence Number: 300179

Title : CHANDRA Observations of RS Oph a Recurrent Symbiotic Nova in Outburst
PI: Starrfield
Abstract: RS Oph is a Symbiotic Recurrent Nova that was last seen in outburst in
1985. We have been monitoring its X-ray evolution with SWIFT and
obtained a HETG spectrum on 26 February UT. The spectrum is well
exposed although the 0th order is piled up. We are following a shock
caused by material ejected from off a white dwarf and moving at speeds
exceeding one thousand km/sec through the outer layers of a red giant.
It is clearly bright enough for CHANDRA and is evolving rapidly as
evidenced by our SWIFT observations. We will continue to obtain SWIFT
observations (PI M. Bode) more often than the CHANDRA observations. T.
O'Brien is doing hydrodynamic modeling of this outburst to better
understand the evolution of the shock. The presence of emission lines
will allow us to obtain abundances and the line profiles differ which
suggests that the material has not been ejected spherically.

Sequence Number: 300178

Sequence Number: 300177

Sequence Number: 300172

Title : CHANDRA Observations of RS Oph a Recurrent Symbiotic Nova in Outburst
PI: Starrfield
Abstract: RS Oph is a Symbiotic Recurrent Nova that was last seen in outburst in
1985 It was observed by EXOSAT. It's outburst commenced on Jan. 26
(IAUC 4030, 4031, 4036). EXOSAT observed RS Oph between 18h00 and
23h00 UT on 1985 Mar. 22. Preliminary analysis indicated that the
x-ray spectrum was soft and absorbed. Fits to a thermal bremsstrahlung
model yielded a temperature of 0.75 keV and an absorbing column
density of ~ 10**21 atoms cm**-2. The flux at Earth in the 0.1-6.0-keV
band was estimated to be 4 x 10**-10 erg cm-**2 s**-1. This was taken
from an IAU Circular by Cordova and Mason in 1985. It has an extremely
rapid decline in Xrays which are probably caused by a shock moving
through a red giant atmosphere.

Sequence Number: 500693

Title : Chandra observation of the Type Ia SN 2005ke
PI: Immler
Abstract: The longest Swift obs. obtained to date (258-ksec) on a SN gives
evidence that the Type Ia SN 2005ke has been detected in X-rays, at a
low level of significance (3-3.5 sigma, CBET 387). See
http://lheawww.gsfc.nasa.gov/users/immler/SN2005ke/Immler_fig1.jpg for
Swift UV and XRT X-ray image. No SN Ia has ever been detected in
X-rays. The Swift UVOT UV lightcurve
http://lheawww.gsfc.nasa.gov/users/immler/SN2005ke/Immler_fig3b.jpg
shows a UV excess starting around 35d after the explosion with respect
to SN Ia lightcurve templates, coinciding with the onset of X-ray
emission. The detection of UV excess is independent confirmation that
the X-rays are from the interaction of the SN shock with CSM as the UV
emission is due to the Mg II emission line at 280 nm. We request a
15-ksec Chandra ACIS-S observation of the nearby (20.7 Mpc) Type Ia SN
2005ke to unambigiously associate the detected Swift X-ray source with
the SN.

Sequence Number: 500692

Title : Accurate positioning of four INTEGRAL selected isolated NSs
PI: Israel
Abstract: Based on the newly discovered hard X-ray spectral characteristics of
AXPs and SGRs we selected 4 dim persistent unidentified radio-quiet
INTEGRAL sources with a relatively bright ROSAT source in their
positional uncertainty regions. In the best case we rely upon a ROSAT
HRI position (3" radius position uncertainty) with no clear optical
counterpart down to V~22, making it a very reliable AXP candidate (the
V upper limit excludes 90% of the known LMXBs). However, several tens
of IR sources are expected in a 3" radius circular region on the
Galactic plane. Chandra is currently the only mission able to obtain
source positions with a sub-arcsec accuracy needed to sort out the
right counterparts of the four sources. Already granted GO XMM
observations will be used to look for pulsations, while Optical/IR
observations will be carried out during the next months. The latter
observations would greatly take advantage of the Chandra positions.

Sequence Number: 500691

Sequence Number: 500690

Sequence Number: 500689

Sequence Number: 400559

Title : Searching for the optical/IR counterpart of the transient X-ray pulsar
Swift J1626.6-5156
PI: Homan
Abstract: The transient 15.3 sec X-ray pulsar Swift J1626.6-5156 was discovered
late 2005. It shares some properties with anomalous X-ray pulsars,but
is most likely a 'normal' X-ray pulsar with some unusual properties.
Determining the nature of the companion star could shed light on the
mode of accretion (disk vs. wind), which in turn might help explain
some of the unusual properties. Recent IR observations seem to rule
out a HMXB as the optical counterpart of the source (ATel 713).
Further attempts at identifying the optical counterpart are hampered
by the uncertainty in the position of the source. The most accurate
position has 90% an error circle of ~3.5 arcseconds (ATel 688).
However, reliable counterparts to other X-ray sources have been found
outside Swift/XRT error circles before (see e.g. Atel 712). The main
goal of the proposed short HRC observation is to improve on the
Swift/XRT position and thereby provide better constraints for
identifying a possible optical/IR counterpart.

Sequence Number: 400558

Title : Eruptive Behavior in HD 109962: A compact object interacting with a W
UMa system?
PI: Walter
Abstract: HD 109962 (vsnet-alert 8794) is in outburst. It is a 0.89 day W UMa
eclipsing binary. It is not a known X-ray source. What makes HD 109962
of interest is that it shows ~0.8 mag outbursts of ~40 day duration
about once a year (see http://ar.geocities.com/varsao/NSV_19448.htm).
The latest outburst began about 12/26/05. A red spectrum on Jan 13.2
shows a P Cygni H-alpha line, indicative of wind emission. The blue
spectrum on Jan 16.2 is astounding. Superposed on a normal F2V
spectrum is a large He II 4686 emission line (EW = -2.9 A). He II 4686
requires a source of highly ionizing radiation. It is certainly not
normally seen in F2V stars or W UMa systems. The ~periodic nature of
the outbursts suggests a model akin to Cir X-1, with a compact object
on a highly elliptical orbit that penetrates the wind from the W UMa
system. It should be a bright X-ray source during the outburst. If so,
followup observations will provide a unique probe of the wind of a
contact binary system.

Sequence Number: 500685

Title : Investigating Circumstellar Interaction in the type Ia SN 2005gj
PI: Pooley
Abstract: The supernova 2005gj was just reported (CBET 302) to display the
signatures of circumstellar interaction. This is only the second
detection of hydrogen in the optical spectrum of a type Ia supernova.
The interaction of SN ejecta with surrounding material should give
rise to X-ray emission, as it does in core-collapse SNe. An
observation with Chandra will measure the luminosity, thus determining
the strength of the interaction. Very little is known about the
progenitors of Ia SNe. Because the X-rays are a great probe of the
circumstellar material around a SN, this Chandra observation could
shed important light on the progenitor system.

Sequence Number: 800555

Title : Probing dark energy using the X-ray gas mass fraction in dynamically
relaxed galaxy clusters
PI: Allen
Abstract: We propose to observe a sample of the most X-ray luminous, dynamically
relaxed galaxy clusters identified from the ROSAT All-Sky Survey and
follow-up Chandra snapshot observations. Our primary goals are to
obtain improved constraints on dark energy and the dark equation of
state parameter using the apparent variation of the X-ray gas mass
fraction with redshift. This project represents an opportunity for
Chandra to take the lead in dark energy work. The observations should
lead to a detection of the effects of dark energy from the Chandra
data alone at the ~5sigma level, using only weak priors on the Hubble
constant and mean baryon density of the Universe. When combined with
CMB and supernova data, the observations should constrain the time
averaged dark energy equation of state parameter, w, to better than 10
per cent accuracy (68 per cent confidence limits). The new data will
also be used for joint X-ray/SZ/lensing studies.

Sequence Number: 300171

Title : HETGS Observation of a Transient Hard X-ray Symbiotic Binary
PI: Sokoloski
Abstract: RT Cru is one of a subset of particularly active symbiotic stars (SS;
white dwarfs accreting from the wind of red giants) characterized by
rapid optical flickering, and in some cases jets and recurrent nova
explosions. The recent detection of RT Cru with INTEGRAL (ATels 519,
528, and 591) indicates that during outburst, it also produces the
hardest X-ray emission of any known SS. In August, RT Cru was observed
with the Swift XRT for 4.7 ks. The XRT observation revealed several
emission-line complexes, a possible broad soft component, and hints of
continuum emission. The line blends could be due to Si, Ca, and Ar.
But Ca and Ar are not strong in nova spectra, and large blue- or
red-shifts are not expected in RT Cru. We request a 50-ks HETGS
observation to resolve and identify the emission lines and any
absorption features, and to isolate the continuum. We will also search
for extended jet structure in the 0th-order spot. This observation
should produce ~2000 counts in the MEG.

Sequence Number: 200372

Title : HRC Imaging of the `Fainted' Primary of the Alpha Centauri System
PI: AYRES
Abstract: The famous Alpha Centauri binary (G2V+K1V) has been regularly observed
in X-rays since first resolved by Einstein 25 years ago, later by
ROSAT/HRI, and more recently by XMM. The latest EPIC-pn imaging
uncovered an extremely odd result: solar twin Alp Cen A has nearly
disappeared in X-rays. This behavior had not been encountered in the
previous quarter century of X-ray work on the system, and is quite
unlike anything ever seen on the Sun, except perhaps the curious
18th-century "Maunder minimum," when sunspots vanished from the solar
disk for decades at a time, and coronal activity likely was severely
depressed; although, of course, we don't have any X-ray observations
from then to confirm the true coronal behavior. The AB orbit now has
closed below the resolution of EPIC, although still is easy for
Chandra to separate. I therefore propose to continue the crucial X-ray
time series on this important solar analog using Chandra's HRC-I.

Sequence Number: 200371

Sequence Number: 200370

Sequence Number: 400472

Title : Confirmation of the Fading Afterglow From the Short Burst GRB 050709
PI: Frail
Abstract: Seven years after the afterglow detections that revolutionized studies
of the long/soft gamma-ray bursts (LSBs), not even one afterglow of a
short/hard GRB (SHB) has been seen. Theoretical calculations suggest
that SHB afterglows will be much fainter than LSB afterglows, faint
enough that ground-based detections should probably not be expected.
Deep Chandra observations, on the other hand, if made within days of
the burst, should be able to find the X-ray afterglow. This appears to
be the case with the recent GRB050709 in which Chandra observations
conducted 2.5 days after the burst detected a source (GCN 3585). Its
flux is consistent with a t^-1.4 power-law decay from the afterglow
peak observed by the HETE SXC at 100 s after the burst. Spectroscopy
undertaken with Gemini of an optical source near the Chandra position
(GCN 3589) yields a redshift z=0.16. The SHB mystery will be solved if
the Chandra source fades away in time.

Sequence Number: 400470

Title : Search for X-Ray Jets from a Millisecond Pulsar
PI: Chakrabarty
Abstract: The nearby (2.5 kpc) millisecond X-ray pulsar SAX J1808.4-3658 is in
outburst as of June 1 (ATEL 505). In its 1998 outburst, the source
showed both radio emission and an infrared excess about 15-20 days
after the outburst peak, suggestive of synchrotron emission from a jet
(Wang et al. 2001, ApJ, 563, L61). Very few NS jet sources are known
(Sco X-1, as well as SS433 and Cir X-1 if they are NSs), and this
source provides the first opportunity to link jet emission to a pulsar
with known magnetic field strength. At a source distance of only 2.5
kpc (in't Zand et al. 2001, A&A, 372, 916), the HRC angular resolution
of 0.4 arcsec corresponds to a separation of 6 light-days at the
pulsar, providing excellent angular sensitivity to a relativistic
ejection.

Sequence Number: 400469

Title : Outburst spectroscopy of the closest accretion-powered millisecond
pulsar
PI: Galloway
Abstract: The visibility of persistent pulsations in accretion-powered
millisecond pulsars (in contrast to other LMXBs) suggests that surface
spectral features might also be more easily detectable. SAX
J1808.4-3658 is the closest of the three MSPs with H-rich donors;
three more are ultracompact and likely accrete primarily He from
degenerate companions. Surface spectral features may arise from
freshly accreted material and the products of spallation reactions,
the rate of which may be greater for H-rich accretors (L. Bildsten,
pers. comm.). Although no high signal-to-noise HETGS spectrum of SAX
J1808.4-3658 has been taken, an opportunity to obtain such a spectrum
has arisen with the early detection of a new outburst on 1 June (ATel
#505). We propose to observe the source with the HETGS for 22 ks in
order to 1) search for discrete emission and absorption features, 2)
characterize the neutral absorption edges and 3) test for flux and
spectral feature variation at the 2.01 hr orbital period.

Sequence Number: 500603

Title : Chandra Observation of the Type IIn Supernova 2005bx
PI: Filippenko
Abstract: We propose to observe the recently discovered Type IIn (narrow
emission line) SN 2005bx. Its optical spectrum (ATEL #475) shows it is
similar to the extremely X-ray luminous SN 1988Z, which was observed
at Lx=1e41 erg/s at an age of 6.5 yr. It is unknown what the
early-time (first few weeks to months) Lx of such a SN would be. A
simple constant-density model of the circumstellar (CS) material
around 1988Z predicts an Lx of 1e43 erg/s at an age of a few months
with a hard spectrum. However, the CS interaction is complicated, and
this naive model may not hold (e.g., there could be absorption by the
CS gas). It is difficult to make clear predictions because of the lack
of knowledge. A 30 ks obs of 2005bx (at 130 Mpc) will reach a
sensitivity of ~1e39 erg/s (4 counts). This early observation would be
unique for this interesting and poorly understood class of SNe.
Chandra may only see 2-3 SNe like this during its lifetime, and this
opportunity should not be missed.

Sequence Number: 701180

Title : Search for strongly obscured AGNs: support for INTEGRAL all-sky hard
X-ray survey
PI: Sunyaev
Abstract: While deep observations of small fields are crucial to study weak
distant AGN, all sky shallow surveys are essential for identification
of brightest and/or nearby objects. This is possible with INTEGRAL,
with large FOV and sensitivity peak above 20 keV where dust obscured
and dust free objects are detected equally well. We recently started
an all sky survey with INTEGRAL. So far half of the sky at |b|>5d has
been scanned and about 70 sources have been detected above 1 mCrab
limit. 80% of them are known bright AGN. 8 objects are unidentified
and absent from the Rosat All-Sky Survey and AGN catalogs. They are
likely obscured AGN. Short Chandra exposure of their 6' error boxes
will provide unambiguous identification and absorption columns. This
will enable immediate optical follow up and assessment of chosen
survey strategy. Being among brightest extragalactic objects, the
targets are good for future detailed study with Chandra and other
observatories.

Sequence Number: 701179

Sequence Number: 701178

Sequence Number: 701177

Sequence Number: 701176

Sequence Number: 701175

Sequence Number: 701174

Sequence Number: 701173

Sequence Number: 500601

Title : GRB050412: The Darkest of the Dark Bursts
PI: Berger
Abstract: Swift localized GRB050412 to few-arcminute precision in real-time
while it was in the night sky over most of the world's major
observatories. While subsequent Swift observations have established
the presence of a fading X-ray afterglow of relatively ordinary flux
(GCN 3253), prompt follow-up observations from UV (GCN 3249) to
optical (GCNs 3238, 3239, 3242) to JHK (GCN 3235) - reaching to
increasingly deep limits from 7.1 sec to 1 hour after the burst - have
established only upper limits to the afterglow flux in these
bandpasses. As with previous events, this is likely due to some
combination of host galaxy extinction and high redshift; since
GRB050412 is the darkest known burst, unusually high redshift and/or
high extinction is indicated. However, the five-arcsec Swift XRT
position will not allow unique identification of a host galaxy. We
therefore propose to make a single Chandra observation to derive a
sub-arcsec position for GRB050412 from its X-ray afterglow.

Sequence Number: 400468

Title : Periastron Observations of a Massive Eclipsing Pulsar Binary System
PI: McLaughlin
Abstract: The 764-ms pulsar J1638-4725 is in an eccentric (e ~ 0.94) orbit with
a 5.3-yr period about a ~ 20 solar mass optically-identified
companion. The pulsar is undetectable in the radio for ~ 1 yr around
periastron, most likely due to absorption and scattering by the dense
stellar environment. During this radio-quiet phase, X-rays from the
"propeller regime" accretion of matter onto the NS magnetosphere are
likely to be detectable. If such emission is detected near periastron
(April 30 2005), this binary will be the first system in which an
accretion phase alternates with a radio pulsar phase, providing a link
between the populations of X-ray transients and radio pulsars and an
important diagnostic of the companion star mass loss rate and its
terminal velocity (and hence mass and radius). X-rays may also be
detected from the pulsar, the companion star, and pulsar wind/disk
shock but are expected to be an order of magnitude less than that
expected from propeller accretion.

Sequence Number: 500600

Title : X-ray observation of a unique radio transient near the Galactic
Center
PI: Hyman
Abstract: We have detected a new unresolved radio transient using the VLA at 330
MHz (Hyman et al. Nature, submitted) which exhibited 10 min flares to
1 Jy at regular 1.25 hr intervals during a 7-hr observation starting
on 2002-09-30. If the source is near the Galactic Center the implied
brightness temperature is several orders of magnitude too high to be
incoherent synchrotron, implying that this is a new class of coherent
emitter. No X-ray emission was seen above 15 mcrab using RXTE bulge
scanning data from the previous and following day, but the field has
never been observed by Chandra or XMM. We propose a 10 ks observation
to search for flaring or quiescent X-ray emission from this source. If
a detection is made this will (1) improve the position of the source
from 10" to <1", (2) constrain source models based on the X-ray flux
and spectrum, and (3) constrain the distance using n_H. If the source
is undetected we will still improve constraints on L_x/L_r by several
orders of magnitude.

Sequence Number: 400467

Title : The nature of the gamma-ray source HESS J1826-148
PI: Funk
Abstract: We (the HESS collaboration) used the first year of operation of the
HESS TeV array to conduct a survey of the inner galaxy. More than a
dozen new and unidentified sources have been discovered (Aharonian et
al., Science, in press). Only one of them, HESS J1826-148, is not
extended and was found to be variable, and should be associated with a
compact object. The TeV source is close to microquasar LS5039, but the
nominal separation of 50" is compatible with a spatial association on
a 9% basis only. Simultaneous XTE-ASM measurements during TeV
observations were uncorrelated. It is plausible that HESS J1826-148 is
actually not coincident with LS5039, but with another compact,
possibly long-lived transient source, which would in any case be the
first example of a new class of TeV emitting sources. We propose DDT
for 8 epochs of simultaneous Chandra & HESS observations to search for
a spatially coincident, hard X-ray source with correlated variability
patterns to enable unambiguous ident.

Sequence Number: 500599

Title : Resolving an X-ray Jet from the Magnetar SGR 1806-20
PI: Kouveliotou
Abstract: On 27 Dec 2004, SGR 1806-20 emitted a giant flare, a once in a century
event with an X-ray peak flux of at least 0.8 erg/cm^2 s. Seven days
later we identified with VLA a bright (172 mJy, 1.4 GHz) expanding
radio source at the location of the SGR, ~500 times brighter than the
radio afterglow seen from SGR 1900+14 following the 1998 August 27
flare. We obtained data with MERLIN separated by 3 days, which show
that within 13 days of the flare a radio structure of angular extent
~100 mas has formed with the peak of the flux displaced ~100 mas
between the two epochs. This elongation immediately suggests a jet
inclined to the line of sight and significantly relativistic, in
analogy with X-ray emission from X-ray binary jets, which have
reheated themselves presumably by the transfer of bulk kinetic energy
to electrons. Discovery of an X-ray jet in a magnetar will provide
unique evidence for the energetics of the shock, the ambient medium
and the B-field of the pulsar.

Sequence Number: 701172

Title : An accretion eruption in the western nucleus of Arp 299
PI: Nandra
Abstract: Monitoring of starburst galaxies in the NIR at WHT in a search for
supernovae (PI: Meikle), has revealed an extraordinary outburst from
NGC 3690, part of merging, LIG system Arp 299 (IAUC 8477). Subtraction
of a Ks image taken on 2005 Jan 30 from earlier images (most recently
2004 June 5) shows a highly variable source within 0.5 of the iron K_
emitter identified by Chandra as the AGN in NGC 3690 (Ballo et al.
ApJ, 600, 634). Such large NIR variability (30%) is generally
restricted to powerful radio-loud QSOs+blazars. What makes this event
even more remarkable is that the AGN in NGC 3690 is usually very weak.
The intrinsic flare is thus likely to be much larger, as the quiescent
NIR emission, which is resolved, is likely dominated by stars. We
propose a Chandra snapshot to confirm the flare and determine its
amplitude. It may be due to a huge accretion event or the rapid
formation of a relativistic jet, heralding NGC 3690 s transition into
a fully-fledged AGN following the merger.

Sequence Number: 500598

Title : The X-ray Fluence of the SGR 1806-20 Hyperflare
PI: Fox
Abstract: On 17 Dec 2004, SGR 1806-20 emitted the brightest burst ever observed
from a Galactic source. This burst, first reported by the Integral
mission (GCN 2920), saturated detectors on every high-energy
satellite. The current lower limit to its fluence, 0.3 erg cm-2 (GCN
2936), would make the burst luminosity roughly 10^46 erg, dozens to
hundreds of times brighter than the "giant flares" that have
previously been observed from other SGRs -- bright enough that
hyperflares in nearby galaxies could contribute to the population of
short-hard gamma-ray bursts (GCN 2942). We propose to make the first
accurate measurement of the fluence in this flare by observing the
X-ray scattering halos produced by molecular clouds between Earth and
SGR 1806-20; five clouds with A_V>2 mag are known from radio
observations (Corbel & Eikenberry 2004, A&A 419, 191). The X-ray rings
from four of these clouds will be observable with Chandra, allowing
four independent estimates of the fluence of the hyperflare.

Sequence Number: 500597

Title : Searching for atomic and/or cyclotron features in the Giant Flares
decay of SGR 1806-20
PI: Rea
Abstract: On 2004 December 27th a Giant Flare from SRG1806-20(GCN 2920) was
revealed, the 1st ever for this source and the 3rd one from SGRs since
1979.The current event is largely more energetic than the previous
ones a rare opportunity to study its decay with the unprecedented
spectral resolution of Chandra,allowing,among other thing to study the
enviroment of the source through the possible presence of spectral
edges/line(similarly to the study performed on GRBs X-ray
afterglows).The comparison of the source emission properties before
and after the flare (XMM obs.carried out few weeks before the
event)will provide an unprecedented opportunity to constrain the
magnetar model and the neutron stars crustal properties.The
possibility of detecting cyclotron features after the flare will
especially be important; in particular,for this source there was
evidence for a cyclotron feature around 5 keV,revealed by RXTE during
a bursting phase.The HETG has the best available resolution around
that energy.

Sequence Number: 200363

Title : Monitoring the X-ray Emission of the Newly Erupted EXor-type V1118
Ori
PI: Audard
Abstract: The origin of the X-ray emission in young, accreting stars remains a
mystery. Accretion seems the dominant mechanism in TW Hya (cool
plasma; high densities). However, other moderately accreting classical
T Tauri stars show high temperatures and low densities. Eruptive young
stars (FUors and EXors) are the key to understanding the importance of
accretion for X-rays since they suddenly display increased accretion
rates from 1E-7 to 1E-4 Msol/year. FUors display brighter and longer
outbursts than EXors but they are far less frequent. Recently, the
(FUor-type) V1647 Ori erupted and triggered an international
observation campaign. In X-rays, Kastner et al. (2004) reported a
30-fold flux increase from the pre-outburst flux, indicating that the
high-energy emission in young stars can increase dramatically due to
the rapid increase of accretion rates in FUor/EXor outbursts. However,
the flux rapidly dropped in the steady high state.

Sequence Number: 400447

Title : Following the decay of the new accretion powered msec pulsar IGR
J00291+5934
PI: Jonker
Abstract: The proposed DDT observations have three goals: 1) As this transient
decays, its magnetic field should become dynamically important. We
will compare the shape of the lightcurve and the spectral information
with that of a NS SXT for which no pulsations have been found. The
strength of the magnetic field is an important unknown quantity for
evolutionary link between LMXBs and msec radio pulsars. 2) A
comparison of the evolution of the SED of this NS SXT with similar
data on black hole (BH) SXTs will constrain the differences in jet
power between NSs and BHs. 3) A comparison of the spectrum and the
luminosity of the source in quiescence immediately after the outburst
with that during an observation in AO7 would allow us to assess the
neutron star cooling after an outburst. Those findings can be compared
with those of the transients XTE J1709-267 and MXB 1658-29 (Jonker et
al. 2003/4; Wijnands et al. 2004).

Sequence Number: 400446

Sequence Number: 400445

Sequence Number: 800557

Sequence Number: 500591

Title : GRB040912: An Unusual Event Exhibiting Strong Spectral Evolution from
a GRB to an XRF
PI: Ricker
Abstract: The WXM on HETE has localized a GRB event that exhibits highly unusual
spectral evolution. Initially, the emission is hard for 10-20 seconds,
evolving to an XRF over the next 200 seconds. No other event like this
has been detected in the 4 years of HETE operations. The spectral
signature is possibly indicative of a very high redshift event. An
prompt, accurate localization of the X-ray afterglow, the spectrum,
and its decay index by Chandra is requested.

Sequence Number: 500590

Sequence Number: 800560

Sequence Number: 800559

Sequence Number: 800558

Sequence Number: 800557

Sequence Number: 800556

Sequence Number: 800555

Sequence Number: 800554

Sequence Number: 800553

Sequence Number: 800552

Sequence Number: 800551

Sequence Number: 800550

Sequence Number: 800549

Sequence Number: 500585

Title : Search for the Counterpart of a New TeV Gamma-ray Source in the
Galactic Plane
PI: Halpern
Abstract: We propose to examine the error box of the second unidentified TeV
gamma-ray source. The IACT array H.E.S.S. has discovered a source in
the 0.6-10 TeV range, designated VHE J1303-63. It is 0.65 deg north of
the famous Be/X-ray pulsar PSR B1259-63, which was also detected. But
the new source is even brighter than the pulsar, about 0.1 Crab, and
its statistical significance is at least 13 sigma (Beilicke, et al.
2004 Heidelberg Gamma-Ray Meeting, and Beilicke, Aharonian,
Heinzelmann, Hofmann, Wagner, private comm.) The error box of VHE
J1303-63 was covered only by a ROSAT observation, which does not show
any counterpart within the error circle. Since this source is in the
Galactic plane (as is the first unidentified TeV source J2032+4130),
it is likely that its X-ray counterpart is highly absorbed. In a
Chandra DDT observation of TeV J2032+4130, we found a possible hard
X-ray counterpart (Mukherjee et al. 2003, ApJ, 589, 487). We propose a
similar search for VHE J1303-63.

Sequence Number: 500508

Title : Observations of an extremely X-ray rich GRB detected by Integral
PI: Kouveliotou
Abstract: Integral has observed an extremely X-ray rich GRB, the richest seen in
3-40 keV. The event was detected with IBIS; it was also the first ever
seen in the Jem-X FOV. The IBIS spectrum is very soft, with a spectral
index of 2.5 and a flux of 1.4e-8 erg/cm^2 s (15-40 keV). It becomes
very faint after 40 keV and is not detectable above 100 keV. The Jem-X
peak flux (3-20 keV) is 0.5 Crab (~1.4 e-8 erg/cm^2 s); most of this
flux comes below 10 keV! This event is thus a prime example of an XRR
GRB, which may be either a classical GRB seen off axis, or a yet
different class considered to be intrinsically subenergetic GRBs.
There are 3 such bursts observed to date, all associated with SNe. We
have approved ESO observations; these, along with information of the
source position, energetics, and spectrum, as early as possible, would
be crucial in understanding the nature of XRR GRBs and may open a new
window in the field, by probing their early properties with the superb
CXO capabilities.

Sequence Number: 500507

Sequence Number: 600412

Title : Monitoring a New X-ray Transient 2.5 Arcseconds South of Sgr A*
PI: Baganoff
Abstract: Chandra observations on 5-6 July reveal a transient 2.5" south (0.1 pc
at 8 kpc) of Sgr A*, in an extreme habitat already known to contain
two dense star clusters and a 3e6 solar-mass black hole. Its 2-8 keV
spectrum (gamma < 0.25) is harder than most INTEGRAL sources. Its
luminosity is >2e34 erg/s, with a possible 4 h period, so it is an
accreting BH or NS, and may emit much of its flux above 10 keV. Thus,
this source may be responsible for much of the emission detected by
INTEGRAL and HESS (TeV) during recent observations of Sgr A*. Also,
diffuse X-rays only 4 light-months from the source have brightened,
suggesting the presence of a jet. We propose to observe the
progression of this outburst: (1) to tell us whether it is active
during upcoming gamma-ray observations, (2) to determine the mechanism
that feeds the source (disk or wind), and (3) to observe the evolution
of the jet. This is a singular opportunity to study the interplay
between accretion, jets, and gamma-ray emission.

Sequence Number: 100052

Title : Chandra by Chandra
PI: Drake
Abstract: A 75ks Chandra observation of the Moon can dramatically increase our
knowledge of lunar geochemistry and provide strong tests of models of
lunar formation and evolution. By resolving fluorescent lines of O,
Mg, Al, and Si, Chandra can provide the first detailed surface
abundance maps of these elements that dominate the crustal and mantle
mineralogy. The results will: (i) provide direct bulk surface
abundances crucial for lunar formation models; (ii) test our
understanding of the Moon's history and crustal evolution through
detailed comparison of abundance ratios within mare, between
geologically diverse lunar surface features, and in craters and ejecta
blankets of different scale; (iii) firmly establish earth orbit X-ray
observation as a powerful means of investigating solar system rocky
bodies; (iv) help prepare for future (c.2005) SMART-1 in-situ lunar
fluorescence measurements; (v) produce high resolution X-ray lunar
images that will likely have significant public appeal.

Sequence Number: 100052

Sequence Number: 100053

Title : Chandra Snapshot Spectral Imaging of Comets C/2001 Q4 (NEAT) and
C/2002 T7 (LINEAR)
PI: Lisse
Abstract: The highly favorable perigee passage of the very bright comets C/2001
Q4 (NEAT) and C/2002 T7 (LINEAR) in late May 2004 provides an
opportunity to study cometary x-ray emission in conjunction with the
new CHIPS spectroscopic mission. In 10 ksec of on-target time for each
comet, ACIS-S will obtain snapshot images of the comets in the heart
of the CHIPS 0.05 0.150 keV spectroscopic monitoring period in
late-May 2004. The combined observations have the potential of
directly detecting for the first time the ultra-soft emission due to
Mg, S, Si, and Fe predicted by McCammon et al. (2002) from soft x-ray
background measurements and by Kharchenko et al. (2000, 2003) from
models of solar wind minor ion charge exchange emission. New work by
Wegmann, Dennerl, and Lisse (2004) allows a determination of the
neutral gas production rate from the spatial scale of the emission,
and an independent determination of the solar wind minor ion flux
density using the x-ray surface brightness.

Sequence Number: 100053

Sequence Number: 100052

Sequence Number: 100053

Sequence Number: 500506

Title : Is GRB 031203 a GRB-SN seen off axis?
PI: Kouveliotou
Abstract: Recent results indicate that there is a common convergence of several
classes of transient phenomena (GRBs, GRB 980425/SN 1998bw, XRFs, and
the most energetic SNe), to a common luminosity ~10^39-10^40 erg/s
about 3-10 years after the explosive event. A simple theoretical
interpretation favors a continuum of events in which the early
luminosity is sensitive to the angle at which the event is observed.
GRB031203 may well be the first of these `gap' events if its X-ray
luminosity can be attributed to its having been viewed substantially
off-axis. Further, if its reported redshift of z=0.105 is confirmed,
GRB031203 is the closest GRB after GRB980425 and thus, an excellent
candidate for a SN to be found in its lightcurve. Indeed, recent
observations (GCN 2544) indicate that this may be the case. Our
suggested 75 ks observation of GRB031203 will provide a luminosity
limit of ~5.5x10^(40) erg/s, comparable to the luminosity seen in SN
1998bw after a few hundred days.

Sequence Number: 100052

Sequence Number: 200298

Title : A Star is Born: X-ray Imaging of the Onset of an FU Ori Outburst
PI: Kastner
Abstract: The highest accretion rates among low-mass stars are associated with
the FU Ori (FUor) phase. This phase is marked by ~100-yr-long
outbursts during which a star brightens by 5-15 magnitudes and its
mass accretion rate likely increases by up to a factor of 10^4. The
'standard model' for the formation of Sunlike stars is that they go
through one or more FUor epochs during their pre-main sequence
evolution, and that this phase(s) is when such stars gain most of
their mass. We propose to observe a newly identified FUor during the
rarely observed rise phase of its outburst. This almost certainly will
be the only chance for CXO to make observations of this evolutionary
phase. These observations will be essential in understanding and
improving models for the formation of all low mass stars, and to
inform the ongoing debate concerning the origin of X-rays from young,
low-mass stars (e.g. Kastner et al 2002, ApJ 567, 434).

Sequence Number: 200297

Sequence Number: 500505

Title : Prompt Observation of the Type Ib/c Supernova 2001em
PI: Pooley
Abstract: The X-ray emission from core-collapse SNe comes from the interaction
of the ejected matter and the circumstellar material, which is the
progenitor's pre-SN wind. It is thus a unique probe of both the
ejected material and the SN environment. We propose a 30 ksec Chandra
obs. of the type Ib/c SN 2001em (which just turned on in the radio; K.
Weiler, IAUC submitted) to determine the X-ray flux to ~5% (see below
for flux estimate) and temperature to ~10%. This information, combined
with continued VLA obs., will determine the mass-loss rate of the
progenitor, thus providing information about both the explosion
environment and the nature of the progenitor. This is especially
important in the case of SNe Ib/c given the association with some
GRBs. Such information will provide a key piece of the puzzle in
understanding the progenitor systems of SNe Ib/c (and by association,
GRBs) and the aftermath of the SN (and GRB) explosion.

Sequence Number: 500504

Title : Monitoring the spectral evolution of RXJ0720-3125 and determining its
nature.
PI: Vink
Abstract: RXJ0720-3125 is a protypical isolated neutron star with a
blackbody-like spectrum. However, we've recently found with
XMM-Newton's RGS that between 5-2000 and 10-2003 its spectrum has
changed. Until 5-2003 this change was slow, but since then the changes
have been dramatic, and the spectrum is now quite distinct from a BB;
it has increased its emission > 0.5 keV & decreased it < 0.5 keV (de
Vries et al. 2004, astro-ph/0401028). We would like to observe this
source with the LETGS in order to see whether the hardening has
continued, is slowly reversing, or whether it is back to its BB-like
state. Moreover, if the source is still in a hard state we need the
LETGS so check whether the absorption < 0.5 keV is Gaussian, in which
case it might be due to proton-cyclotron absorption. NB the deviations
from a BB may relevant to the whole class of isolated NSs, as all of
them may have similar but less obvious deviations from a BB spectrum.

Sequence Number: 701014

Title : Multiwavelength Reverberation Mapping of NGC 4395, the Least Luminous
Seyfert 1 Galaxy
PI: Moran
Abstract: NGC 4395 is the least luminous Seyfert 1 galaxy known, and one of the
most X-ray variable. Its extremely small BH mass implies
light-crossing timescales 100-1000 times shorter than in luminous AGN.
A multiwavelength reverberation mapping campaign on this object
spanning the UV (HST), optical (KPNO 4m & Lick 3m), and IR (KPNO 2.1m
& IRTF 3m) has been approved for two 8-hr periods in April 2004. We
propose to use this unique opportunity to conduct simultaneous
monitoring (2 x 30ks) with Chandra. A previous Chandra observation
revealed extremely rapid, large-amplitude variability and dramatic
long-term spectral variability. Our program will allow us to compare
for the first time the X-ray variability in an AGN of this luminosity
to the UV/optical/IR continuum and emission-line variability. Apart
from indicating the state of the ionizing source during the
reverberation campaign, the Chandra data can shed new light on the
accretion and emission processes in this enigmatic AGN.

Sequence Number: 701013

Sequence Number: 500503

Title : GRB 031203: A Possible Analogue to GRB980425/SN1998bw
PI: Kulkarni
Abstract: GRB03120, a seemingly typical burst was localized to a 5-arcmin region
by Integral. XMM found a source with initial flux of 3E-13 erg/cm2/s
which faded as t^{-0.4} during t=0.25 to 6 days. Separately, we
detected a slowly fading radio counterpart. The X-ray/radio source is
coincident with a bright, z=0.105 galaxy. Relative to other
afterglows, the fading of the radio/X-ray is unusually slow.
Furthermore, the 1E+43 erg/s X-ray luminosity and the 1E+29 erg/s/Hz
radio luminosity are 10 - 1000 times less than for typical afterglows,
yet comparable to those observed for GRB980425/SN1998bw. Most
curiously, there is no optical afterglow or hint of an underlying
supernova. Keck host spectrum rules out an AGN origin for the X-ray
source. We conclude that GRB 031203 is a new type of cosmic explosion
with some parallels. As argued below, our continued VLA campaign
complemented by the proposed Chandra observations offer us the best
chance to decipher the nature of this mysterious source.

Sequence Number: 300145

Title : Outburst in Mira AB?
PI: Karovska
Abstract: The nearby system Mira AB composed of an aging AGB star (Mira A) and a
WD companion (Mira B) offers a unique laboratory for studying wind
accretion processes, a poorly understood phenomenon in many sources.
Recent Chandra ACIS-S Obs.(70ks on 12/6/03; PI.M.Karovska) resolved
for the first time the components (~0.6") in X-rays, and detected a
new bright soft source (< 0.7 keV) in addition to the harder (1-4 keV)
emission from Mira B. The new source is spatially and spectrally
separated from Mira B and likely associated with Mira A. This is the
first detection of X-rays from an AGB star. This source was not
detected by ROSAT in 1993 or recently by XMM 8/03 (AAS/03,J.Kastner),
and could be a transient phenomenon. Model fitting shows that the soft
X-ray emission is likely several emission lines, rather then a
continuum; with ACIS spectral resolution we cannot resolve or identify
these lines. We propose a 40ks LETG+HRC-S obs. to identify the lines
and determine the emission mechanism.

Sequence Number: 300144

Title : A HRC-S LETG Observation of V4743 Sgr
PI: Starrfield
Abstract: We have observed V4743 Sgr three times with CHANDRA (March, July, and
September 2003) with our last cycle ToO program but are now out of
time. We are requesting an additional observation to follow its
evolution back to minimum. Our first observation found a large
amplitude oscillation with a period of ~1300 s (see Sept 2003 ApJ
Letters). Our Xray observations showed that the oscillations were
multi periodic, and that the principal period is increasing. These
results suggest that we are observing non-radial modes and that the
surface characteristics of the WD are evolving on a few month time
scale. We are analyzing the spectra and find that the white dwarf
temperature at the first grating observation was about 600,000K. We
are seeing the WD cool slightly with time. The light curve and
spectral variations are very exciting and we would like to follow the
evolution as long as there is nuclear burning on the white dwarf.

Sequence Number: 400376

Title : A Search for X-Ray Emission from the Double-Pulsar Binary System
J0737-3039
PI: McLaughlin
Abstract: We have discovered the first double neutron star binary, J0737-3039,
in which both stars are observable radio pulsars. The spin periods of
the recycled pulsar, A, and its companion, B, are 22 ms and 2.7 s. The
stars are separated by only 2.9 light seconds in a 2.4-hr orbit. At a
distance of only 500 pc, this system promises to be the best ever
laboratory for relativistic astrophysics. Observations of B show its
flux to vary greatly, making it only detectable for two brief periods
when it is in front of A. This variation is likely due to the
interaction of A's spin-down luminosity, in the form of a relativistic
wind and Poynting flux, with B's magnetosphere. We also see a brief
(22 sec) eclipse of A as it passes behind B. A detection of
non-thermal X-rays from A will provide, for the first time, a probe of
the magnetosphere and local environment of a neutron star. We may also
detect thermal X-rays from B or X-rays from the shock interactions of
this extremely relativistic system.

Sequence Number: 500500

Title : Understanding the nature of the unidentified EGRET source 3EG
J1631-4033
PI: Foschini
Abstract: The EGRET unidentified sources represent one of the most challenging
enterprises of the modern astrophysics. In the 3rd EGRET catalog there
are 271 sources, 170 of them are still unidentified. The identified
sources are mainly blazars (93) and pulsars (5). Now that the most
probable sources are identified, it remains to understand if there are
other populations of objects able to generate high energy (E>100 MeV)
gamma-rays, or if there are different engines powering known objects,
like - for example - transition objects between FRI radio galaxies and
BL Lac or off-beam gamma-ray pulsars of the Gould belt. Given the
high-energy gamma-ray (EGRET) and the hard-X (ISGRI) spectral and
temporal characteristics, this source could be the first example of
off-beam gamma-ray pulsars of the Gould Belt, predicted by several
authors like I. Grenier, N. Gehrels, A. Harding, et al.

Sequence Number: 500499

Title : SN 2003jd; A GRB-like hypernova
PI: Watson
Abstract: SN 2003jd has been identified as a peculiar Type Ic (Stanek et al. GCN
2431) showing strong similarities with SN 1998bw near maximum. However
the spectrum does not match well with other peculiar type Ic's like SN
1997ef or 2002ap. There is an association between GRBs and hypernovae
(HNe), (1998bw/980425 & 2003dh/030329) and it has been suggested that
HNe are GRBs observed off-axis and that HNe-without-GRBs may have
early X-ray emission identifiable with non-thermal afterglow-like
emission. SN 2003jd is an excellent candidate, the best to date, for a
GRB-like HN without an observed GRB and represents an opportunity to
examine the characteristics of a GRB-less HN where the HN appears to
be very similar to those observed in GRBs. The paucity of X-ray data
on HNe & this HN's similarity to a GRB, prompts us to request an
initial imaging observation with Chandra (with a possible follow-up
observation after 1 month), to determine the X-ray luminosity and the
behaviour of the lightcurve.

Sequence Number: 500498

Title : Unveiling the multiwavelength spectrum of the AXP XTEJ1810-197
PI: Israel
Abstract: XTEJ1810-197 is a newly discovered Anomalous X-ray Pulsar (AXP), first
detected by XTE and INTEGRAL and then observed by Chandra (DDT obs.
carried out on 28 August 2003) and XMM (ToO obs.; see Gotthelf et al.
2003, astro-ph/0309745). XTEJ1810-197 is also the first confirmed
example of a transient AXP. The Chandra data allowed to detect
XTEJ1810-197, about 15' off-axis, resulting in a less accurate
position (radius of about 2.5"; 1sigma). On October 7th we carried out
deep IR obs. with the adaptive optic instrument (NACO) mounted on the
VLT. These data allowed us to sort out four faint (Ks>19.5) IR
counterpart candidates to XTEJ1810-197. The latters are separated each
other of more than 1" (within the Chandra uncertainty region of radius
2.5"). Therefore, the requested Chandra on-axis obs. will allow us to
unambiguously identify the counterpart to XTEJ1810-197 (position with
radius of about 0.6" at 90% c.l.).

Sequence Number: 200237

Title : Understanding the X-ray emission from the Homunculus Nebula
PI: Corcoran
Abstract: An ACIS-S+HETGS observation of Eta Car (July 20 2003) during the
star's X-ray minimum (when the intrinsically bright stellar source is
hidden from view) discovered surprisingly hard X-ray emission from the
homunculus, the massive bipolar nebula ejected from the star during
the Great Eruption. The origin of this emission is unknown. Two
alternatives: the emission might be hot (50 MK) gas filling the
spherical lobes of the nebula (the emission should be constant and may
be important in the future dynamical evolution of the nebula) or it
could be scattered radiation from the strong stellar source (the
emission should vary with the stellar flux, but with light travel time
delays). To distinguish between these alternatives we request a short
ACIS-S observation without the gratings. This observation must take
place before the end of the X-ray minimum, since outside minimum the
stellar emission is so bright that the nebular emission is mostly
hidden in the wings of the stellar psf.

Sequence Number: 500415

Title : Locating the Transient AXP XTE J1810-197
PI: Gotthelf
Abstract: The newly discovered 5.5s X-ray pulsar XTE J1810-197 (Markwardt et al,
AUC 8168) is the 2nd example of a transient AXP (TAXP). Unlike the
original TAXP, AX J1845-058 (Gotthelf & Vasisht 1998, NA, 3, 293),
this new source was found prior to its fading away; furthermore, an
archival XTE detection provides a spin-down rate, confirming its AXP
status. TAXPs may be related to a growing class of young, isolated NSs
whose properties are distinct from young rotation-powered pulsars, and
whose basic physics is unknown. Examples are, the central compact
object (CCO) in SNR RCW 103, whose flux is variable over years and
lack pulsations, the Cas A point source, another possible quiescent
AXP, based on its spectrum and central SNR location, and the original
TAXP, AX J1845-058, found to be associated with a SNR. Chandra
provides a unique opportunity to characterize a fading AXP, and to
determine an possibly evolutionary link with the CCOs, thus unifying
these mysterious manifestations of NSs.

Sequence Number: 500413

Title : SN2002ic and its Circumstellar Medium
PI: Hughes
Abstract: Supernova (SN) 2002ic (IAUC 8019) is the first thermonuclear or Type
Ia SN ever to show hydrogen in its spectrum (IAUC 8151). Hamuy et al
(astro-ph/0306270) argue that the H alpha emission of the SN arises
from a dense circumstellar medium (CSM), which itself was the result
of pre-SN mass loss from a massive asymptotic giant branch star that
was the companion to the white dwarf that exploded as the SN. This
result could have wide implications for the origin of SNe Ia and their
cosmological use. This study is based on observations taken between
November and February; our more recent VLT data from July continue to
show strong H alpha emission. Radio emission has not been detected
(IAUC 8157), which can be explained if there is substantial free-free
absorption in the CSM gas. Hard X-ray observations are the most
sensitive probe of the CSM surrounding SN Ia; here we propose X-ray
observations of SN2002ic to detect the shocked CSM and confirm the
high mass loss rate of the progenitor.

Sequence Number: 500412

Title : ToO observations of SGR 1806-20 in an active state
PI: Woods
Abstract: SGRs are a class of high-energy transients that emit brief, intense
bursts of soft gamma-rays. There is now strong evidence in support of
the idea that SGRs (and AXPs) are magnetars. SGR 1900+14, SGR 1627-41
and the AXP 1E 2259+586 have shown that during epochs of intense burst
activity, there are changes in the persistent and pulsed emission
properties of the underlying X-ray source. Quantifying these changes
has shed light on the burst mechanism and the consequences of bursts
in magnetars. Details are given in the AO-4 and AO-5 proposals by
Woods et al. SGR 1806-20 recently entered a new phase of activity. As
yet there have been no detections of changes in the persistent
emission of this source during periods of burst activity. The
transient effects of burst activity seen in SGR 1900+14, SGR 1627-41
and 1E 2259+586 are markedly different. Given the low number of
magnetars, it is important to study these transient effects whenever
possible to better understand their nature.

Sequence Number: 400324

Title : Localization and Spectroscopy of the Millisecond X-Ray Pulsar XTE
J1814-338
PI: Chakrabarty
Abstract: A new msec X-ray pulsar (MSXP) , XTE J1814-338 (P=3.2 ms, Porb=1.9 hr)
was just discovered (Markwardt, IAUC submitted). Its orb params are
very similar to those of pulsar SAX J1808.4-3658, the only XRB known
with a brown dwarf donor. J1808 also the only one of 4 prev known
MSXPs whose orb params and disk geometry led to a bright opt
counterpart in outburst. The new psr appears to be geometrically very
similar (from orbit), and it is now anti-Sun, ideal for optical/IR
obs. We are obtaining Magellan optical/IR obs of field, but cannot
obtain opt spectra until 2 arcmin position improved, since field
crowded. Also, J1808 showed strange IR/radio excess early in 1998
outburst that may have been synchtroton (ApJ, 563, L61); if so, soft
X-ray sync excess also expected, possibly with jets, a first for a
NS/pulsar. J1808 was never observed with CXO in outburst. We request
ACIS/HETG for 10 ks to (1) localize source, (2) look for soft
excess/extension, (3) spectrum, (4) HETG to limit pileup.

Sequence Number: 800375

Title : A Chandra Survey of a uniformly-selected sample of high-redshift
galaxy clusters.
PI: Bautz
Abstract: This request is being submitted after consulation with the CXC
Director to compensate for unusually high background during, and
premature termination by SCS 107 of obsid 3577 (seq 800298.) This is a
routine (non-time-critical) request. The high background and early
termination substantially reduced the signal:noise ratio of this
extended, high-redshift cluster.

Sequence Number: 400323

Title : Determining the Nature of the Peculiar X-ray Transient IGR
J16358-4726
PI: Kouveliotou
Abstract: IGR J16358-4726 was discovered on 03/19 2003. Our March 24 CXO
observation serendipitously detected the transient at the 1.7e-10
erg/cm^2 s flux level (unabsorbed) with a very high absorption column
(NH=3.3e23 cm^-2). The spectrum is a hard power law of index 0.5; we
see a significant Fe line and possibly Ni line. A strong flux
modulation with a period of 5860s is clearly visible in the data. The
frequency of this modulation appears to change within the observation.
The only neutron star systems known with similar spin periods are low
luminosity persistent wind-fed pulsars; if this is a spin period, this
transient is a new kind of object. If this is an orbital period, then
the system could be a compact LMXB. We request follow up CXO
observations to quantify short term changes in the 5860s periodicity
and perform phase resolved spectroscopy.

Sequence Number: 500411

Title : Chandra LETG/ACIS Observation of H2650 (=GRB030328)
PI: Ricker
Abstract: GRB030328 is a very bright, long GRB localized to arcminute accuracy
by the HETE SXC in real time at 1120 UT. An observation commencing in
less than 20 hours may permit the detection of Si and S lines (Butler
et al 2003) at a high level of significance.

Sequence Number: 400322

Title : DETERMINATION OF THE POSITION OF THE MILLISECOND PULSAR XTE J1807-294
PI: MARKWARDT
Abstract: Millisecond pulsars are probably the endpoint of evolution of low mass
X-ray binaries (LMXBs). However, the actual detection of neutron star
spin frequencies in LMXBs has been problematic. To date, four
accreting millisecond pulsars have been found, with the fourth, XTE
J1807-294 having been discovered 25 Feb 2003. Three of the four known
pulsars have orbital periods of 35-43 min, which suggests that there
is a common evolutionary origin. We request Chandra HRC-S observations
in "Imaging Mode" primarily to determine the position. This will
enable observations at other wavelengths. Detection of an optical
counterpart of XTE J1807-294, in outburst or quiescence, can aid in
determining the system size and inclination, but because of the
confused galactic center region, it is important to have a precise a
priori position.

Sequence Number: 500410

Title : GRB030226: TESTING THE DUST DESTRUCTION HYPOTHESIS
PI: Pedersen
Abstract: GRB030226 was discovered by HETE-2 and an optical transient identified
2.6h later. The redshift has now been measured to z=1.99 placing it in
an ideal redshift window for combined X-ray and lyman alpha studies:
It is close enough for X-ray absorption in the vicinity of the burst
to be measurable in the CXO spectrum and far enough that lyman alpha
can be reached from the ground. Combining the two measurements with
optical/NIR observations we can accurately determine the amount of
oxygen and iron (dominating the X-ray absorption), the amount of
neutral hydrogen, and the dust content in the GRB environment. For
this burst, we can thus tell if the low dust content, found in most
burst environments, is due to either a) low metallicity and a
universal dust-to-metals ratio, or b) solar metallicity, but a low
dust-to-metal ratio. In case b) most of the metals are in the gas
phase - indicating significant dust destruction.

Sequence Number: 400321

Title : THE BHC SOFT X-RAY TRANSIENT XTE J1908+094 RETURNING TO QUIESCENCE
PI: Jonker
Abstract: With the Chandra satellite we can study the spectra of SXTs as they
fade into quiescence. This has never been done for a BHC SXT!
According to evolutionary and SXT outburst theories there may exist a
whole class of persistent but faint accreting BHCs at low Mdot; their
accretion disk is cold and hence not prone to the SXT outburst
mechanism. Up to now there is very few information on spectral states
for BHCs for ~2 orders of magnitude in flux (~10^-7-10^-5 Edd.; there
is spectral information of BHCs in quiescence at ~10^-8 of Edd.).
Gallo et al. 2003 have demonstrated the existence of a universal
coupling between observed X-ray and radio flux from hard state BHCs,
of the form L_radio~L_X^0.7, over three orders of magnitude. We
propose to extend this relation down to ~5x10^-7 Edd. assuming d=10
kpc. This would demonstrate that jet production is the standard
behavior and it is only in the limited range in Mdot in which a
standard thin disc is formed that a jet is not produced.

Sequence Number: 400320

Sequence Number: 400319

Sequence Number: 400318

Title : AN HETGS OBSERVATION OF GX 339-4 IN THE LOW/HARD STATE: ACCRETION
GEOMETRY, RELATIVITY, AND JET FORMATION
PI: Miller
Abstract: [The full SJ is contained in an email to the director.] A sensitive
spectrum of a transient Galactic black hole in the low/hard state can
address at least 3 of the most fundamental issues in X-ray astronomy:
1) major pictures for changes in accretion flow geometry with the mass
accretion rate (m-dot), 2) relativistic effects near black holes, and
3) jet formation. GX 339-4 is an ideal target for this purpose. At
present, grating spectra and even CCD spectra obtained from sources in
this state have collected < 10^4 counts each (in the best cases),
insufficient for strong constraints. Our proposed grating observation
will obtain appx 10^6 counts in the dispersed spectrum. We will use
continuum spectroscopy and the shape of the Fe K-alpha line to
constrain the radial location of the inner disk, and thereby the
nature of the flow geometry and the role of the disk in jet formation
in the low/hard state.

Sequence Number: 500409

Title : EXPLORING THE GRB-SUPERNOVA CONNECTION VIA SN2003L
PI: Kulkarni
Abstract: The type Ibc SN 1998bw provides a link between GRBs and supernovae.
Like GRBs, it had relativistic ejecta (as inferred from the brilliant
radio emission and early non-thermal X-ray emission) but with lower
Lorentz factor. Ordinary SNe do not show bright radio emission at
early times and theoretically appear unable to produce significant
relativistic ejecta. Thus it is generally assumed that SN 1998bw
harbored a central engine. For the past four years, we have been
searching for other such engine-driven SNe and have recently reported
bright emission from the type Ic SN2003L. With a radio luminosity that
is currently 1.9E+28 erg/s/Hz (15% of SN1998bw at peak) and rising,
this event is very similar to SN1998bw. A detection of non-thermal
X-ray emission (synchrotron or inverse-Compton) would confirm the
inference of relativistic ejecta and mark SN 2003L as another link
between GRBs and SNe. A 30 ks observation will allow a rough
determination of the spectrum.

Sequence Number: 100038

Title : A SEARCH FOR SOFT X-RAY AURORAS ON EARTH
PI: Gladstone
Abstract: Chandra HRC-I observations of Jupiter made in Dec. 2000 in support of
the Cassini flyby have revealed the surprising result that jovian
auroral x-ray emissions are concentrated in a small `hot spot' which
pulsates with a ~45-m period. The location of the hot spot near the
magnetic pole implies a particle source region near Jupiter's
magnetopause, and high-latitude reconnection of heavy solar wind ions
is now a viable explanation for these soft x-ray emissions. The
identical process should operate at Earth as well. Hard x-ray
emissions from electron bremsstrahlung are well known in the
terrestrial aurora. Surprisingly, however, there have been no searches
of Earth's aurora for emissions at <2keV. We propose here a simple
slew observation by HRC-I across the auroral region to look for
Earth's soft x-ray aurora. The detection of a Jupiter-like hot spot at
Earth would imply that heavy ion solar wind charge exchange is
important for producing x-rays at planets as well as comets.

Sequence Number: 500408

Title : THE DECAYING X-RAY AFTERGLOW OF GRB021004
PI: Sako
Abstract: Observations of the afterglow of GRB021004 have provided us with a
unique opportunity to study the detailed physical conditions of the
burst environment. The optical light curves are densely sampled since
~9.5 minutes after the burst and consist of multiple bumps and wiggles
on various timescales. The X-ray light curve, however, is sampled only
during an earlier Chandra HETG observation, which lasted ~1 day
starting from ~20.5 hours after the burst. The temporal slope during
this observation was determined to be -1.0 +/- 0.2, and there was no
obvious change in spectral shape throughout the observation. As
stressed by Heyl & Perna (astro-ph/021004), the X-ray light curve is
particularly important for distinguishing between the various possible
emission models. We propose to measure the X-ray flux and the spectral
shape of GRB021004 during its late afterglow phases to address the
long-term behaviour of this spectacular afterglow.

Sequence Number: 500407

Title : PROMPT CHANDRA OBSERVATION OF THE TYPE IIN SN 2002HI
PI: Lewin
Abstract: We propose to observe the Type IIn (narrow emission line) SN 2002hi.
Its optical spectra show it is similar to the extremely X-ray luminous
SN 1988Z (IAUC 8006), which was observed at Lx=1e41 erg/s at an age of
6.5yr. It is unknown what the early-time (first few weeks to months)
Lx of such a SN would be. A simple constant density model of the
circumstellar (cs) material around 88Z predicts an Lx of 1e43 erg/s at
an age of a few months with a hard spectrum. However, the cs
interaction is complicated, and this naive model may not hold (e.g.,
there could be absorption by the cs gas). It is difficult to make
clear predictions because of the lack of knowledge. A 10ks obs of 02hi
(at 260 Mpc) will reach a sensitivity as low as ~1e40 erg/s. This
early obs would be unique for this interesting and poorly understood
class of SNe. Chandra may only see 2-3 SNe like this during its
lifetime, and this opportunity should not be missed. In the future, we
will propose for these SNe under Peer Review.

Sequence Number: 500406

Title : PROMPT CHANDRA OBSERVATION OF THE TYPE II SN 2002HH
PI: Lewin
Abstract: We propose to observe the Type II SN 2002hh. As we have shown, Chandra
data will constrain details of the pre-SN evolution and properties of
the SN ejecta and the circumstellar (cs) matter. In our simulations,
we have assumed 1999em-type and 1998S-type spectra, with appropriate
distance and absorption. If 02hh is like 99em, a 30 ksec obs can
determine the flux to ~25% and the temperature to ~50%, which would
constrain cs interaction models. If 02hh is like 98S, we expect ~0.1
cts/sec. A 30ks obs would give us more counts than the >100ks spent on
98S, and we would ALSO be able to determine elemental abundances to
~25-40%, which is even better than was done for 98S. This will
constrain the progenitor mass as it did for 98S. The ONLY REASON we
wish to not trigger our 200ks A04 TOO is the high extinction to 02hh.
If we could use 30ks (and save 170 for another occasion) WE WOULD, but
that may not be allowed. A 30ks DDT obs is a sensible and effective
way to seize this rare opportunity.

Sequence Number: 500405

Title : SPECTROSCOPIC OBSERVATIONS OF THE BRIGHT AFTERGLOW OF GRB021004
PI: Harrison
Abstract: One of the holy grails of gamma-ray burst research is to detect X-ray
line signatures from an afterglow with high statistical significance.
Of all possible observations, this perhaps offers the best chance of
constraining the GRB mechanism and environment, and could provide the
"smoking gun" signature connecting GRBs to massive stellar deaths. In
order to accomplish this, we know long observations within one day of
the event are necessary.

Sequence Number: 500404

Title : GRATING OBSERVATION OF GRB020813
PI: Ricker
Abstract: The SXC on HETE has just localized a very bright (>10 Crab) GRB to an
accuracy of 1 arcmin. Within minutes of the burst location being
disseminated, an optical transient was discovered in the SXC error
box. HETE is expected to detect only 2-3 such events per year with the
SXC. Since this burst has some X-ray characteristics reminescent of
GRB011121 (Reeves et al 2002), a grating observation with Chandra
could establish definitively whether hydrogen-like emission lines from
non-iron metals are characteristic of bright GRBs, as is predicted by
the "supranova" model (Vietri and Stella 1999).

Sequence Number: 600330

Title : SEARCHING FOR THE X-RAY SIGNATURE TO CURRENT RADIO ACTIVITY IN M31*
PI: Primini
Abstract: M31*, the radio source identified with the super-massive black hole in
M31, has recently brightened significantly, from ~50+/-9 microJy on
July 5 to ~90+/-9 microJy on July 29 (5 GHz, VLA). This is the first
significant evidence for radio variability. We request a 5 ksec ACIS-I
observation to determine how this variability is reflected in x-rays.
The typical luminosity of the x-ray counterpart, in several Chandra
observations, is ~4e36 ergs/sec (0.5-7 keV) but it has occasionally
brightened by a factor of 2-4. However, there are no contemporary
radio observations and thus the x-ray/radio correlation is unknown. A
Chandra observation of unusual activity in the x-ray counterpart NOW
would: 1) strengthen the x-ray identification with M31*, which is now
based only on position; 2) constrain source emission models, some of
which predict anti-correlated radio and x-ray variability.

Sequence Number: 400316

Title : INVESTIGATION OF THE UNIQUE UNIDENTIFIED TEV SOURCE, TEV J2032+4130,
IN CYG OB2
PI: Butt
Abstract: Observation by HEGRA at TeV energies has revealed the first, and only,
unidentified TeV source, TeV J2032+4130 at the 4.6sigma level in Cyg
OB2 association. It is marginally consistent with the location of
unidentified EGRET (GeV) source 3EG J2033+4118 and has luminosity
~0.03 Crab in TeV. The source's 2sigma error location circle is just 6
arcmin in radius, well suited to CHANDRA ACIS-I field of view. Chandra
data on point-like vs. diffuse emission + spectra will constrain
source. In particular, we will resolve whether one of the sources
observed by ROSAT, 2RXP 203218.1+412807, seen in one of our Cyg OB2
datasets could be related to the TeV emission -- we cannot tell if the
ROSAT source is intrinsically diffuse or point-like, nor can we yet
constrain its spectrum. We expect an ACIS-I ct rate of ~0.25 cts/sec
from this source. There is some urgency since the source may show
variability on timescales of months. Please see astro-ph/0207528 and
Benaglia et al., A&A,366,605.

Sequence Number: 400315

Title : V4641 SGR DURING OUTBURST: FAST JETS & VARIABLE CORE
PI: Rupen
Abstract: The black-hole X-ray binary (BHXB) V4641 Sgr was discovered in 1999;
0.5" radio jets were seen within 24h of the X-ray flare. Another
outburst in May has produced ongoing optical/radio/X-ray activity. The
apparent jet velocities (9.5c) are the highest yet known; in a few
months they may easily extend over an arcmin. With the past 2 months
of activity, this is an ideal time to look for such extended emission.
The high quiescent luminosity (10x > BHXBs of similar orbital period)
and the strong, very wide Fe line seen in 1999 both suggest X-rays
from the jets: Doppler boosting may explain the luminosity, & the Fe
line suggests entrained/shocked material. We request ToO data to image
these putative X-ray jets, and to check for variability both in the
jets & in the central source. There is an accepted A04 proposal
(Tomsick); but it is important also to observe during the current
outburst, given the extreme variability and high proper motions. We'd
be happy to share these data with Tomsick.

Sequence Number: 400270

Title : OBSERVATION OF CYG X-1 IN THE HIGH STATE WITH HETG/CHANDRA
PI: Feng
Abstract: The 7 HETG/Chandra observations of Cyg X-1 covered the low(LS),
transition(TS) and high(HS) states that showed variable spectral
features. Recent 3 observations (5ks) in HS showed an evidence for
broad Fe K line which is markedly different from that of LS and TS. It
indicates that the disk line may be distorted significantly by strong
relativistic effects near the black hole in HS.However, poor S/N line
profiles in HS did not allow us to measure the relativistic effects,
the inner accretion disk radius which is generally believed very close
to the last stable orbit and can be used to determine the spin of the
hole, ionization states, inclination, etc. We propose 60 ks CC-mode
HETG/Chandra observation of Cyg X-1, which has settled in rare
HS(HR2<0.7, ASM/RXTE since April 2002) to detect the broad line. It is
important also in understanding the physical process which causes the
state transition. A simultaneous RXTE observation will also be planned
to constrain the continuum above 5 keV.

Sequence Number: 400268

Title : FURTHER IMAGING OF THE JETS OF THE BLACK HOLE XTEJ1550-564
PI: Corbel
Abstract: Following our discovery of a radio jet from the black hole candidate
XTEJ1550-564 (IAUC 7795), we detected X-rays from both the western and
eastern jets. The western jet has a sharp peak along its leading edge
(away from the BHC) and is extended along the trailing edge. The
spectrum is a power law with a photon index near 1.7. The eastern jet
gives the first detection of proper motion in X-rays for a jet from a
black hole and proves that the jets move with relativistic speeds on
large scales as hypothesized for AGN jets. The proposed observation
will allow us to study the dynamics of jet/ISM interactions on time
scales inaccessible for AGN jets by determining the evolution of the
flux, morphology, and spectrum of the jets. We will measure the proper
motion of the western jet to an accuracy of 3 mas/day which will show
whether it is still travelling at relativistic speeds (the average
proper motion up to March was 18 mas/day) or has reached a termination
shock.

Sequence Number: 400267

Title : THE LOW/SOFT STATE IN THE MICROQUASAR 1E1740.7-2942
PI: Heindl
Abstract: Based on RXTE monitoring, the microquasar 1E1740.7-2942 has faded and
softened dramatically, entering a "low/soft" state seen only in its
twin microquasar, GRS1758-258. It is unlikely that this state will
occur again for a decade. The usual black hole "high/soft" state
appears at high luminosity, but this low/soft state appears while the
source is dim/fading. We speculate that this is caused by the shutoff
of accretion to two simultaneous flows: a thin disk and a hot, radial
coronal flow. The transition occurs because the hot flow accretes away
rapidly (free-fall timescale) while the disk is consumed on the
viscous timescale (weeks). GRS1758-258 showed an exponential flux
decay with a timescale of about a month after the transition. We
expect similar behavior in 1E1740.7-2942. Chandra will confirm the
presence of a simple disk spectrum seen now without a corona. If the
corona has been ejected, it may detect jets via extended morphology or
Doppler shifted emission lines.

Sequence Number: 400266

Sequence Number: 400265

Title : SPECTROSCOPY OF THE HIGH-LATITUDE ACCRETING MILLISECOND PULSAR XTE
J0929-314
PI: Chakrabarty
Abstract: The 3rd msec X-ray pulsar, XTE J0929-314 (Pspin=5.4 ms, Porb=43 min)
was just discovered (IAUC 7893). Along with the other two (SAX
J1808.4-3658, Pspin=2.5 ms, Porb=2 hr; XTE J1751-305, Pspin=2.3 ms,
Porb=42 min), this establishes a pattern of msec pulsars being found
in very close binaries. The donors in ultracompact binaries (Porb < 80
min) are H-poor and likely degenerate. As seen in CXO observations of
the ultracompact 4U 1626-67 (Schulz et al. 2001, ApJ), this exotic
composition can be traced through X-ray spectroscopy. The source (like
1626) is high-latitude (14 deg) and low-column (Nh<1e21), making it an
ideal target. (J1751 was at Galactic ctr!) From orbital size, a C-O or
O-Ne-Mg donor is likely. We request LETG/ACIS spectra to search for
emission lines and absorption edges. (ACIS for larger area <50 A.) We
also hope to compare the edges with HST UV Ly-alpha measurement of Nh
(HST DDT prop submitted) to explore local composition (cf. 1626
paper).

Sequence Number: 500298

Title : SN2001IG: DETECTING A MASS LOSS PHASE?
PI: Schlegel
Abstract: The X-ray emission of supernovae is a young field with relatively
little data. X-rays provide information about the circumstellar ejecta
as the outgoing shock runs into matter from previous phases of mass
loss. A reverse shock is created which generates low-energy X-rays (~1
keV) while the outgoing shock generates harder events. The X-rays
probe the circumstellar matter and are expected to provide measures of
abundances in spectral lines. The X-ray light curve (LC) additionally
provides a measure of the matter distribution (Ref for SN: Schlegel
1995, Reports on Prog in Physics, 58, 1375). The radio LC of SN1979C
has been interpreted as revealing waves of mass loss (Weiler et al.
1992, ApJ, 399, 672) from the progenitor. No other SN has shown such
behavior prior to the recent increase in the radio LC of SN2001ig. We
expect the hard and soft X-rays to behave differently, directly
testing shock/reverse shock theory.

Sequence Number: 500297

Sequence Number: 500296

Title : CHANDRA ARCSECOND LOCALIZATION OF THE X-RAY FLASH XRF020427
PI: Fox
Abstract: The X-ray flashes (XRFs) are identified in BeppoSAX observations as
fast X-ray transients that exhibit the properties of gamma-ray burst
(GRB) prompt X-ray counterparts while lacking detectable gamma-ray
emission (Heise et al. 2001, astro-ph/0111246). The XRFs are
distinguished from Galactic phenomena by their nonthermal spectra,
fast evolution, and near-isotropic sky distribution. However, the
absence of gamma-ray emission means that either (1) the XRFs originate
at very high redshifts, z>5; or (2) the XRFs are a GRB-like phenomenon
with Lorentz factors intermediate to GRBs (L>100) and supernovae
(L~1). Chandra, VLA, and HST observations of XRF011030 established for
the first time that, in at least this case, the XRF was the result of
(2) a highly energetic explosion at a cosmological distance z<3 (GCNs
1136, 1143, 1268). Chandra observations of the XRF020427 will allow us
to identify and study only the second such cosmological X-ray flash.

Sequence Number: 500295

Sequence Number: 400247

Title : A FAINT NEUTRON STAR SOFT X-RAY TRANSIENT RETURNING TO QUIESCENCE
PI: Jonker
Abstract: Approx 10 SXTs like SAXJ1808.4-3658 form a class of faint SXTs,
calculations show that the NS magnetic field will not be buried in
these systems. We propose to obtain three observations of a faint SXT
as it returns to quiescence. Monitoring observations will allow us to
observe the transition from a spectrally hard state in outburst to a
soft spectral state in quiescence. To find out which emission
mechanism is responsible for the low-level X-ray emission, it is
crucial to get good 0.1-8 keV spectra and to identify at which
luminosity the transition from hard to soft takes place. For this
study the low N_H of this source is vital. Given a neutron star
magnetic field strength, for lower mass accretion rates (unaccessible
for RXTE) the magnetosphere will be larger and the polar caps onto
which magnetically channelled matter accretes smaller, resulting in
larger pulsed fractions. Observations with ACIS-S in CC mode will
allow us to search for pulsations at frequencies less than 166 Hz.

Sequence Number: 400256

Title : VARIABLE THERMAL EMISSION AND FEATURE FROM AQL X-1 IN QUIESCENCE
PI: Rutledge
Abstract: Aql X-1 went into outburst Feb 15 (ATEL 83) and was below 3 sigma
detection in the 1-day ASM countrate on Mar 25. On Apr 1, it has been
undetected with ASM for 7 days, which indicates it has returned to
quiescence. We request observations to monitor the quiescent spectrum
and intensity over 140 days, for 2 goals: (1) Long-term
time-variability was observed between our 4 AO1 observations of Aql
X-1. The variability may be secular, due to slow atmospheric-related
processes, as opposed to stochastic processes like accretion-power.
(2) Two important phenomena related to accretion were observed during
only one (of the four) observations: short time-scale variability
(32+8-6% rms, 1-10000 sec timescale) and a (time-variable) deficit of
counts in the 0.45-0.6 keV band, where the first absorption feature
due to metals in a NS atmosphere should occur. Multiple observations
with the previous sensitivity can again detect variability and the
deficit of counts in >1 observation.

Sequence Number: 400255

Sequence Number: 400254

Sequence Number: 400253

Sequence Number: 400252

Sequence Number: 400251

Sequence Number: 400250

Sequence Number: 400249

Title : OBSERVATIONS OF THE NEWLY DISCOVERED MILLISECOND ACCRETING PULSAR XTE
J1751-305
PI: MARKWARDT
Abstract: Millisecond pulsars are probably the endpoint of evolution of low mass
X-ray binaries (LMXBs). However, the actual detection of neutron star
spin frequencies in LMXBs has been problematic, with SAX J1808.4-3658
being the only known millisecond accreting pulsar. The newly
discovered source (03 Apr 2002) XTE J1751-305 was detected by RXTE PCA
as a 435 Hz pulsar. Ultimately we hope to measure the orbital period
and determine mass constraints for the primary and secondary stars.
This will lead to constraints on population evolution of LMXBs. A
position determined from the BeppoSAX WFC (by J. in 't Zand) refines
the position to within 1.2 arcmin. Because this region is near the
galactic center, a rapid and accurate X-ray position determination is
important. This will enable prompt follow-up observations in the IR
and radio bands. We request Chandra HRC-S observations in "Imaging
Mode" primarily to determine the position, and also to improve the
timing solution.

Sequence Number: 400248

Title : AN ACCURATE POSITION FOR THE BLACK HOLE CANDIDATE XTE J1908+094
PI: Rupen
Abstract: We request a 1 ksec ACIS-S scan of the new transient J1908+094, to
obtain an accurate position to pin down a possible IR/radio
counterpart, as well as a quick X-ray spectrum. The source was
detected by chance during PCA observations of SGR 1900+014 on 21 Feb
2002; a scan on 18 Mar gave a 2' error box ~24' from the SGR, and
showed it had risen from 26 to 64 mCrab (IAUC 7856). The timing
characteristics (IAUC 7856) and a strong hard tail (IAUC 7861) make
this a strong black hole candidate. The field is quite confused in the
near IR, and although our INT I image (19 Mar) suggests a possible
faint counterpart, our VLA data (21-22 Mar) show no radio source at
that position, though there is another (~1 mJy) source within the RXTE
error box. We need a Chandra position to either confirm the IR or
radio counterpart, or to allow much deeper limits based on more
accurate astrometry. There are other possibilities; the I band image
for instance does not rule out a blue counterpart as in J1655-40.

Sequence Number: 500294

Title : CHANDRA ARCSECOND LOCALIZATION OF THE DARK BURST GRB020321
PI: Fox
Abstract: Roughly 1 in 3 arcminute-scale GRB error boxes fail to yield an
optical transient despite intensive ground-based searches. These "dark
bursts" must be subject to severe optical extinction, either within
their host galaxy or because they are located at z>5. Well-localized
dark bursts thus identify highly obscured star-forming galaxies or
galaxies close to the epoch of reionization - objects of great
interest in either case. We propose to localize the dark burst
GRB020321 with a single 20-ks Chandra observation. Despite rapid
notification and a small error box (GCNs 1284, 1285), prompt
observations have failed to reveal an optical or radio afterglow of
this burst (R<24; GCNs 1289, 1305). Given the 2'-radius localization
we anticipate at most two interloping X-ray sources; comparison with
optical datasets will thus allow a unique identification of the GRB
afterglow. The expected X-ray flux will be extrapolated from BeppoSAX
observations to further cement the source identification.

Sequence Number: 400246

Sequence Number: 400239

Sequence Number: 400238

Sequence Number: 400237

Sequence Number: 300090

Title : CHANDRA HETG SPECTROSCOPY OF GK PER IN OUTBURST
PI: Mauche
Abstract: GK Persei is an extraordinary object: the first nova of the last
century, it contains a magnetic white dwarf, an evolved secondary, and
a large truncated accretion disk. ASCA demonstrated that in outburst
the X-ray spectrum of GK Per contains strong Fe K emission lines and a
strong low-energy (0.5-3 keV) excess. The nature of the low-energy
excess is not known, but it is expected to consist of a mixture of
thermal emission lines from the accretion column and fluorescent
emission lines from the white dwarf surface and accretion disk. We
propose to obtain two Chandra HETG observations of GK Per in outburst
to determine the nature of the low-energy emission, measure the Fe K
emission line strengths, and search for other emission lines, thereby
constraining the accretion geometry and the plasma conditions (range
of temperatures, abundances, and density) of the X-ray--emitting
plasma.

Sequence Number: 300089

Sequence Number: 100034

Title : SPECTROSCOPIC IMAGING OF CHARGE EXCHANGE X-RAY EMISSION FROM COMET
C/2002 C1
PI: Dennerl
Abstract: Comet C/2002 C1, discovered on February 1, 2002, is predicted to be as
bright as 4 - 5 mag when it will become observable with Chandra from
April 10, 2002. We propose to utilize this opportunity for direct
spectroscopic imaging with ACIS-S. This has never been done for such a
bright comet. Thanks to a favorable observing geometry, we can apply a
novel observing technique: as the comet will slowly move along the
comet-Sun line, an automatic scan of the x-ray emission properties
will be provided along this direction, where the charge exchange model
predicts a characteristic spectral evolution, which could, however,
not be tested so far. While previous Chandra images and spectra of
comets suffer from low photon statistics, we expect to get about 40
times more photons than from C/LINEAR S4. This will allow us to
utilize the full spectral and spatial resolution of Chandra. A
detailed Scientific Justification is provided in the attached
Postscript file.

Sequence Number: 500292

Title : TOO OBSERVATIONS OF SGR 1900+14 IN AN UNUSUAL ACTIVE STATE
PI: Woods
Abstract: Previously, we have found that the counterpart to SGR 1900+14
underwent extraordinary spectral changes during burst active episodes
in 1998 and 2001. It is during these epochs where we have gained the
most insight into the nature of this source. SGR 1900+14 recently
entered a new phase of activity starting on 2/17. Our ToO observation
of the SGR on 2/19 with the RXTE PCA found the flux (2-10 keV) to be a
factor of ~20 higher than expected. The pulsed signal of the SGR is
not seen in the data, nor is the pulsed signal of a nearby Be
transient (XTE J1906+09). There are no other catalogued X-ray
transients in the 1 degree radius FWZM fov of the PCA. The power
spectrum did show an excess level of red noise, similar to that seen
in many BHCs. We conclude that we are observing either (i) the rise of
a new transient or (ii) new behavior from SGR 1900+14 in an active
state. A PCA raster scan has shown that the excess emission is
consistent with the direction of the SGR.

Sequence Number: 400236

Title : IMAGING THE JET/ISM INTERACTIONS AROUND THE BLACK HOLE XTEJ1550-564
PI: Corbel
Abstract: We discovered a new radio source, 22" West of the black hole
XTEJ1550-564 (IAUC 7795; 2002 Jan 19). Subsequent observations show it
has a variable spectrum, is extended toward XTEJ1550 and is located
along the axis of the VLBI jets observed during the Sept 1998 radio
flare. Our Chandra images from Aug-Sept 2000 show an extended X-ray
source also along the VLBI jet axis, but directly opposite the radio
source (23" to the East), and with similar flux during the two Chandra
observations (21 days apart). We found a transient radio source in
archival data at this position in Feb 2001, indicating a lifetime of a
few months. It is likely that both components represent superluminal
plasmons ejected during the Sept 1998 major radio flare and
interacting with the ISM. The proposed Chandra observation will allow
us to study the physics of jet/ISM interactions and the total power of
relativistic jets, with implications for our understanding of
relativistic jets from AGN.

Sequence Number: 100034

Sequence Number: 500291

Title : LOCALIZATION OF OPTICALLY-DARK GAMMA-RAY BURSTS BY CHANDRA
PI: Ricker
Abstract: Observation will be a second epoch ACIS-I image of the field of a HETE
X-ray rich GRB (XRF011130). The first epoch ACIS-I 30 ksec observation
took place on 10 December. It has been proposed that X-ray rich GRBs
may be at redshifts Z > ~10. To date, no X-ray rich GRB counterpart
has ever been identified. In the first epoch observation, ~20
candidates were established. Since the Chandra X-ray candidates were
localized to <1 arcsec accuracy by Chandra, followup imaging by HST
and spectroscopy by ~8 meter-class ground-based telescopes can
immediately take place after the second epoch Chandra data is
reduced.

Sequence Number: 500287

Title : CHANDRA IDENTIFICATION OF THE X-RAY COUNTERPART OF GRB020127
PI: Fox
Abstract: Roughly one-third of arcminute-scale gamma-ray burst (GRB) error boxes
fail to yield any optical transient in spite of intensive ground-based
follow-up efforts. These so-called "dark GRBs" are likely extinguished
in the optical by dust and gas in their host galaxy: in the one dark
GRB identified (in the radio) so far, GRB970828, modeling efforts
indicate an extinction of >10 mags in R-band (Djorgovski et al. 2001).
Such large extinctions are characteristic of molecular clouds and
star-forming regions, and thus shed light on the nature of GRB
progenitors. The 8-arcminute-radius error circle of GRB020127 was
reported by the HETE-II team within 4.5 hours of the burst (GCN 1229),
was well-placed for immediate observations, and was observed from at
least two facilities (GCNs 1230, 1234), without identification of a
counterpart. Our best hope for counterpart identification thus lies
with the Chandra observations proposed here.

Sequence Number: 500286

Sequence Number: 300087

Title : TOO OBSERVATIONS OF THE RECURRENT NOVA IM NORMAE IN OUTBURST
PI: Starrfield
Abstract: IM Nor is a Recurrent Nova (RN) discovered in outburst on 10 Jan 02.
It rose to V~7.7 on 16 Jan suggesting that it was caught at the
beginning of its outburst. Based on its first outburst in 1920 (near
maximum for ~ 100 days), it is one of only two SLOW RN. While CHANDRA
observed another RN with ACIS-S (CI Aql in 2000), the resulting
spectrum was weak. However, CI Aql was fainter at maximum and the
spectrum was taken after it had returned to quiescence. RN may be
progenitors of SN Ia suggesting that we need to obtain as much
information as we can about their properties. We, therefore, propose a
5 ksec ACIS-S observation to see if it is bright in X-rays followed by
a 25 kse c HRC-S+LETG spectrum to study the ejecta. The ACIS-S
spectrum will show either emission lines from a hot gas (seen in V382
Vul) or a hot continuum from a white dwarf atmosphere (V1494 Aql).
Neither of these resemble the spectrum of a dwarf nova (WZ Sge).

Sequence Number: 700612

Title : CHANDRA MONITORING OF A MICROLENSING EVENT IN MG J0414+0534
PI: Chartas
Abstract: Recent Chandra monitoring of the gravitational lens (GL) system MG
J0414+0534 indicate that images C and B are possibly undergoing
microlensing events. The microlensing event in image B is of
particular interest since it is accompanied by a five-fold increase of
the equivalent width of a reprocessed narrow Fe Ka line in the
spectrum of image B. This sudden increase can be explained with a
caustic crossing that selectively enhances a strip of the reflection
emission region of the accretion disk. The main goal of the proposed
DDT observations is to directly probe the various emission regions of
an accretion disk from scales of a few hundred gravitational radii
down to the event horizon of the black hole. We expect to achieve this
goal by monitoring changes in the line energy, intensity, and profile
of an Fe Ka line in image B as a magnification caustic is traversing
the accretion disk of the distant z = 2.64 radio loud quasar MG
J0414+0534.

Sequence Number: 100032

Title : X-RAY OBSERVATIONS OF THE FIRST COUNTERPART TO A FAST X-RAY TRANSIENT,
XRF010930
PI: Harrison
Abstract: Thanks to BeppoSAX we are now aware of a new type of transient --
X-ray flashes (XRFs, also called Fast X-ray Transients). About one
third of the events seen by the WFC are XRFs. Until today, NOT A
SINGLE member of this class has been localized to arcsecond accuracy.
Only gradually has the community come to appreciate that XRFs have a
rate comparable to GRBs. There are two possibilities: 1. XRFs are
highly redshifted GRBs (e.g. Heise, Lloyd) 2) XRFs are explosive
events producing Lorentz factors intermediate between GRBs and SNe and
thus peak in the X-ray. On 30.25 October 2001 (UT) the BeppoSAX Wide
Field Camera (WFC) detected a XRF, XRF011030, and a Chandra DDF has
found an X-ray source coincident with a radio transient (see below).

Sequence Number: 100031

Title : X-RAY OBSERVATIONS OF THE FIRST COUNTERPART TO A FAST X-RAY TRANSIENT,
XRF010930
PI: Harrison
Abstract: Thanks to BeppoSAX we are now aware of a new type of transient --
X-ray flashes (XRFs, also called Fast X-ray Transients). About one
third of the events seen by the WFC are XRFs. Until today, NOT A
SINGLE member of this class has been localized to arcsecond accuracy.
Only gradually has the community come to appreciate that XRFs have a
rate comparable to GRBs. There are two possibilities: 1. XRFs are
highly redshifted GRBs (e.g. Heise, Lloyd) 2) XRFs are explosive
events producing Lorentz factors intermediate between GRBs and SNe and
thus peak in the X-ray. On 30.25 October 2001 (UT) the BeppoSAX Wide
Field Camera (WFC) detected a XRF, hereafter XRF011030, unaccompanied
by any increased rate in the Gamma Ray Burst Monitor (GRBM) on SAX,
HETE-2 or Ulysses.

Sequence Number: 400234

Title : CYGNUS X-1 IN THE HIGH STATE
PI: Cui
Abstract: Cyg X-1 is now in a rare high state, as seen by the ASM and radio
monitoring. Such a state transition occurs only once every few years,
and therefore offers a great opportunity for us to conduct a detailed
study of this important black hole candidate in the high state, making
use some of the unprecedented capabilities offered by Chandra.
Previous Chandra observations of the source have revealed the presence
of numerous emission lines and absorption edges (Schulz et al. 2001).
There is already evidence that the line emission seems to vary
depending upon the state of the source (low state vs. flare). It
would, therefore, be very interesting to see how the source behaves in
the high state. The results would almost certainly shed light on the
difference in X-ray production processes and the binary environment
between the low and high states, and, ultimately, on the physical
process that is responsible for triggering a state transiton.

Sequence Number: 500285

Title : ARCHIVAL RESEARCH FOR ISOLATED NEUTRON STAR RXJ185635-3754
PI: Tananbaum
Abstract: A long LETG observation will provide a high signal-to-noise
high-resolution spectrum, permitting a search for the signatures of
heavy elements (beyond He) in the neutron star atmosphere. If such
features can be detected and identified, their redshift and profiles
can be used to provide constraints on the neutron star equation of
state.

Sequence Number: 700608

Sequence Number: 500285

Sequence Number: 400233

Title : LOCALIZATION AND IDENTIFICATION OF THE X-RAY TRANSIENT IN NGC 6440
PI: in 't Zand
Abstract: X1745-203 in NGC 6440 is one of five X-ray transients in galactic
globular clusters, with recorded outbursts in 1971 and 1998. The last
outburst (In 't Zand et al, 1998, A&A 345, 100) was followed up by us
with VLT and NTT observations which identified two candidate optical
counterparts (Verbunt et al, 2000, A&A 359, 960). Both of these have
counterparts in a Chandra observation of NGC 6440 taken during
quiescence in July 2000. An accurate position of the X-ray transient
while it is active would secure the identification of the quiescent
X-ray as well as the optical counterpart. With such an identification,
we can study the quiescent X-ray emission and determine what it is due
to. One of the most likely explanations is emission from a cooling
neutron star; if so, given the known distance, we can directly measure
the neutron-star radius. ASM/RXTE observations show that X1745-203 has
gone into outburst again, and this presents the opportunity to
determine the position of the transient.

Sequence Number: 700607

Title : CHANDRA OBSERVATIONS OF THE THREE HIGHEST REDSHIFT QUASARS FROM THE
SDSS
PI: Brandt
Abstract: X-ray studies of the highest redshift quasars provide insight into the
evolution of quasar central power sources and environments. Large
X-ray efforts (e.g., XEUS and Constellation-X) are being planned to
study the z=5-20 Universe despite a lack of X-ray information on the
Universe at these redshifts. Chandra can efficiently provide precious,
basic information on the highest redshift quasars due to its high
sensitivity. Three high-redshift quasars at z=6.28, 5.99, 5.82 have
been recently discovered by the Sloan Digital Sky Survey; they are
bright with AB_1450=19.7, 19.6, 18.8. We propose exploratory Chandra
observations of these three objects designed to define their basic
X-ray properties and determine if spectroscopic X-ray observations are
merited. If these quasars are detected, this will hopefully capture
the public's interest leading to further appreciation of the power of
Chandra. Co-Is on this proposal are SDSS members Anderson, Fan, Gunn,
Richards, Schneider, Strauss, Voges.

Sequence Number: 700606

Sequence Number: 700605

Sequence Number: 300067

Title : FIRST X-RAY OBSERVATIONS DURING AN EXTREMELY RARE OUTBURST OF WZ SGE
PI: Kuulkers
Abstract: The cataclysmic variable (CV) WZ Sge has unexpectedly gone into
outburst on 2001 Jul 23 (IAU Circ 7669). Outbursts were seen in 1913,
1946 and 1978 (e.g. ApJ 248, 1067), suggesting a recurrence time of
~33 years. These extremely rare outbursts, and their decline to
quiescence have NEVER been covered in X-rays. With Chandra we have the
unique opportunity to study WZ Sge for the first time through these
phases. In quiescence the accretion disk is truncated by the white
dwarf magnetic field and X-ray oscillations (PASP 110, 403) at 27.9s
were observed. In outburst the disk reaches the white dwarf surface
(e.g. MNRAS 305, 473) and possibly the oscillations cease to exist. By
taking 10 ksec snapshots of WZ Sge 3 times in the next 2-3 months, we
will catch WZ Sge in its various states, and get information on
accretion rate onto the white dwarf, abundances, and temperatures,
etc. (e.g. MNRAS 288, 649). We have requested a DDT on HST as well
(PI: E. Sion).

Sequence Number: 300066

Sequence Number: 300065

Sequence Number: 300061

Title : WZ SGE IN OUTBURST TEN YEARS EARLY: II THE X-RAY EMISSION
PI: Wheatley
Abstract: This is the second half of the WZ Sge DDT proposal. In the first we
requested HRC-S/LETG spectrscopy of the EUV emission. Here we request
ACIS-S observations of the (probably weak) X-ray emission. The X-ray
emission is likely to be supressed below its usual quiescent level
during the outburst, as the emission is thought to switch to the EUV.
However, WZ Sge has never been observed in X-rays during outburst.

Sequence Number: 300059

Title : WZ SGE IN OUTBURST TEN YEARS EARLY: I THE EUV EMISSION
PI: Wheatley
Abstract: WZ Sge is the most extreme dwarf nova. While most dwarf novae exhibit
outbursts every few weeks with optical amplitudes of 2-3 magnitudes,
WZ Sge waits thirty years between outbursts which then have amplitudes
of 7 mag. These have never been studied in X-rays. WZ Sge is in
outburst right now (began around July 23.5 UT) presenting a unique
opportunity to observe it in outburst with Chandra. We are extremely
lucky because the outburst was not expected for another ten years, and
may not repeat for another 30 years. In general dwarf novae are weak
hard X-ray sources in quiescence and strong EUV sources in outburst.
We may expect the same behaviour from WZ Sge though we must also be
prepared for unexpected behaviour from such an extreme system. Count
rates are highly uncertain, but we may expect WZ Sge to be the
brightest EUV source in the sky. We propose LETG spectroscopy to study
the EUV component and ACIS-S spectrscopy of the (probably weaker) hard
emission.

Sequence Number: 300058

Sequence Number: 300057

Sequence Number: 300056

Title : THE RECURRENT NOVA CI AQL
PI: Greiner
Abstract: We propose a 20 ksec ACIS-S observation of the recurrent nova (RN) CI
Aql. RNe are expected to emit soft x-rays during an interval after the
ejected shell has become optically thin and before the hydrogen
shell-burning ceases and the white dwarf cools. A 2 ksec Chandra
ACIS-S observation on June 1, 2001 discovered that CI Aql was a soft
X-ray source 380 days after outburst. The flux was much smaller than
expected. It is possible that the shell is dense and/or expanding
slowly; i.e. we may still be near the beginning of the soft X-ray
phase. If obscuration is still important, the proposed observation
will detect a distinctive spectral signature and will measure the
ejected mass, testing whether CI Aql is a possible SNIa progenitor. If
obscuration is not important, we will determine the temperature and
luminosity of the white dwarf. Making these measurements and adding a
second point to the X-ray light curve, will significantly add to the
evolving understanding of the properties of RNe.

Sequence Number: 300054

Title : THE RECURRENT NOVA CI AQL
PI: Greiner
Abstract: Recurrent novae (RN) are expected to emit soft x-rays during a short
interval after the ejected shell has become optically thin and before
the hydrogen shell-burning ceases. Observations of the soft x-rays
will test theoretical models and will also test the conjecture that RN
are SN Ia progenitors. Unfortunatley, no RN occurred during the ROSAT
years, and in fact only one has been detected as a soft X-ray emitter
(Kahabka etal 1999). CI Aql went into outburst in Apr. 2000. Hachisu &
Kato (2001; astro-ph/0104461) predict that CI Aql should have recently
become active at soft X-ray wavelengths and is potentially detectable
until Aug. 2001. We propose (1) a 2 ksec ACIS-S observation to verify
the existence of soft X-rays, and (2) if soft X-rays are discovered, a
20 ksec LETG-HRC observation to determine crucial parameters (white
dwarf mass, effective temperature, composition, luminosity, wind
properties).

Sequence Number: 500200

Title : TOO OBSERVATIONS OF SGR 1900+14 IN AN ACTIVE STATE
PI: Kouveliotou
Abstract: SGR 1900+14 has just emitted a second giant flare (GCN #1041); this is
the second source, which has emitted giant flares (01/04/18 and
98/08/27), in the last 20 years. SGR flares are extremenly rare events
and release over 10^44 ergs. The previous flare, changed the pulse
shape of the neutron star significantly (from four peaks to a single
peak sinusoid) indicating dramatic B-field changes. We have evidence
(yet unpublished) that the pulse shape is changing back to its complex
form. We wish to investigate and understand: 1) whether there is
another pulse shape change associated with the current SGR activity,
2) whether there is a persistent flux change and confirm the
persistent flux-flare energy output relation we have seen previously,
and 3) whether we confirm a line around 6 keV seen during a burst
emitted two days after the SGR 1900+14 August 27, 1998 flare. If this
is a proton cyclotron line, we will for the first time be able to
measure directly the magnetic field of a magnetar

Sequence Number: 500199

Title : IMMEDIATE POST-GIANT FLARE OBSERVATIONS OF SGR 1900+14
PI: Kulkarni
Abstract: The Soft Gamma-Ray Repeaters (SGRs) are thought to be magnetars:
isolated neutron stars with dipolar magnetic field strengths in excess
of 1e14 G. The best evidence for this identification are the "giant
flares" of these sources, which are highly super-Eddington and require
the confining pressure and reduced photon cross-section of a strong
B-field. The 27 August 1998 flare of SGR 1900+14 peaked at L_X > 2e43
erg/s and powered a short-lived synchrotron nebula of 8.5 GHz flux >
0.3 mJy at its peak. Chandra ACIS-S observations of SGR 1900+14 in the
near aftermath of its recent flare (GCN 1041) will enable a search for
spectral features in the post-flare X-ray emission, which may exhibit
~1e37 erg/s bursts of its own. Strohmayer & Ibrahim (2000) have
reported a ~6.4 keV line with XTE observations of SGR 1900+14;
detection of this line with ACIS will provide valuable insight into
these objects. Coordinated observations with the VLA/VLBA are
underway, and will be arranged with RXTE.

Sequence Number: 700393

Title : THE ORIGIN OF THE DRAMATIC FLUX AND SPECTRAL VARIABILITY IN THE
CIRCINUS GALAXY
PI: Matt
Abstract: The Circinus Galaxy is one of the nearest AGN and the brightest
Compton-thick Seyfert 2. Due to heavy obscuration, below 10 keV the
spectrum is dominated by a reflection component, the nucleus starting
to be observable above ~20 keV. No evidence for variability was
present before we observed the Circinus Galaxy with BeppoSAX on 2001
January 7. The source has dramatically changed with since June 2000
both in flux and spectral shape. Below 10 keV, the flux increases by
almost 50\%,the spectrum becoming steeper. Above that energy, the
change was much smaller, if any. There are two explanations: a) A past
variation of the nuclear emission echoed by the reflection component.
b) A burst from a off-center source reaching the luminosity of 10**40
erg/s, as that observed in M82 and attributed to accretion onto a
black hole with a few hundred times the solar mass BeppoSAX cannot
solve this ambiguity. Only a high angular resolution observation with
Chandra can do it.

Sequence Number: 400164

Title : HIGH RESOLUTION SPECTROSCOPY OF THE POSSIBLE JETS IN GRS 1758-258
PI: Heindl
Abstract: As of 28 Feb, the microquasar GRS1758-258 has entered an extremely dim
x-ray state (RXTE- IAUC submitted). This is unlikely to happen again
for 10 years. Two HRC observations in 2000 Sept/Oct revealed a
variable point source plus elongated (~1") emission. In one month, the
morphology changed showing the likely formation of an ~arcsecond x-ray
jet. At the likely source distance (8.5kpc), relativistic bulk motion
would be required. The current state is ~3x dimmer in RXTE than
typical. We suspect the point source has turned off, and the residual
flux is from ejected material. Cui et al. (ACIS/HETG,
astro-ph/0009380) found extended emission around another microquasar,
1E1740.7-2942, and may have detected spectral lines, but they could
not separate the core and extended components. We will measure the
spectrum of the extended (jet?) emission without point source
contamination. This has the possibility of discovering red and
blue-shifted emission lines a la SS433.

Sequence Number: 400163

Sequence Number: 400162

Title : A CHANDRA OBSERVATION OF THE LONG-DURATION TRANSIENT AND NEUTRON STAR
LOW-MASS X-RAY BINARY KS 1731-260 IN QUIESCENCE
PI: Wijnands
Abstract: The full scientific justification is sent in an email to the Director.
The long-duration transient KS 1731-260 has been active for over a
decade, however, our recent RXTE/PCA observations show that the source
has now gone back in to quiescence. This opens the oppertunity to
study the affects of prolonged accretion onto the neutron star on the
quiescence X-ray properties of a neutron star X-ray transient. This
would be the first time ever that such a study can be performed.
Considerable differences (e.g., a considerable higher luminosity
compared to that of short-duration transients) are expected if the
quiescence properties depend on the time averaged accretion rate in
outburst. We will also obtain an excellent position of the source
allowing the identification of its optical and infrared counter
parts.

Sequence Number: 800178

Title : REOBSERAVTION OF PKS0745-191
PI: Fabian
Abstract: GT observation of this cluster has high background with many flares.
Plots of this background have been shown and discussed, by email, with
Harvey Tananbaum.

Sequence Number: 500197

Title : CHANDRA OBSERVATION OF THE X-RAY AFTERGLOW OF GRB010222, THE BRIGHTEST
GRB OBSERVED BY BEPPOSAX
PI: Piro
Abstract: Chandra observations of X-ray afterglows of GRB provide unique
results. The 1 arcsec positional accuracy, high sensitivity to faint
sources, combined with the unprecedented spectral capabilities of this
instrument will permit: 1)unique and fast counterpart identification
in other wavelenghts, OR a deep study of the property of the GRB site
(host galaxy) to ascertain the nature of dark GRB (i.e. GRB Without
Optical Transient) 2)To study the afterglow spectrum in its early
(bright) and late phases, with the unprecedented potential capability
to detect line spectral features. Both of these goals have been
already demonstrated in our previous observations with CXC (e.g. Piro
et al 2000, Science290,956)

Sequence Number: 400161

Title : CHANDRA OBSERVATIONS OF CYGNUS X-1 IN A RARE, SUSTAINED HIGH/SOFT
STATE
PI: Miller
Abstract: The full SJ is contained in an email to the Director. A clear
High/Soft State was observed in Cyg X-1 between 15 Oct. and 15 Nov.
2000 (mean flux: 0.5-1 Crab, 2-12 keV RXTE ASM). Following a short
Low/Hard state, the mean rate returned to ~1 Crab on 7 Dec. 2000. This
flux and observed spectral softness indicate that Cygnus X-1 has
entered a second sustained High/Soft state episode. This outburst
profile is similar to the 83-day High/Soft state observed May-Aug.
1996 (see http://xte.mit.edu/~rr/cygx1.ps). A Chandra observation of
Cygnus X-1 (PI, Canizares; Cui et al. in prep.) in the Low/Hard state
shows evidence for an Fe K-alpha line, Fe L edges (Cui et al, in
prep). The dynamics and geometry of the L/Hard and H/Soft state are
expected to be markedly different. Measurements of the iron e

Sequence Number: 900066

Title : AN ULTRADEEP SURVEY IN THE CHANDRA DEEP FIELD SOUTH
PI: GIACCONI
Abstract: We propose to exploit the unique combination of angular resolution,
sensitivity and field-of-view of the Chandra ACIS imager to perform
the deepest X-ray survey ever in the well-studied "Chandra Deep Field
South" (CDFS). With a total integration time of 1.5 Msec (request for
this AO: 1 Msec) we reach a 0.5-2 keV flux limit of 2E-17 cgs. We aim
to detect >500 sources, i.e. AGN to z=10, clusters to z=3 and
starburst galaxies to z~1. Simulations based on the existing 130 ksec
observation in the CDFS and realistic source counts and correlation
function models show, that Chandra exposures will not be background or
confusion limited up to 3Msec. We propose to make the Chandra data
public immediately.

Sequence Number: 900066

Sequence Number: 200125

Title : CAPTURING WR140 AT PERIASTRON WITH THE CHANDRA HETG
PI: Pollock
Abstract: This is a resubmission of our AO2 proposal number 02200508 which was
rejected, despite high scores, because it was mistakenly thought that
XMM would be making similar observations near periastron. In fact,
according to its official WWW visibility tool, XMM is not able to
observe any nearer than two months either side of periastron passage
and possibly not at all. The compelling scientific justification was
given in our original proposal and endorsed by the Peer Review. We are
responding to the Review Panel's recommendation to apply for
Director's Discretionary Time.

Sequence Number: 200124

Sequence Number: 300053

Title : THE NATURE OF CLASSICAL SYMBIOTIC OUTBURSTS
PI: Charles
Abstract: Symbiotic stars may be the progenitors of the cosmologically important
Type Ia SNe. The high accretion rate onto the white dwarfs (WDs) in
these binaries allows for steady, rather than explosive burning as in
classical novae. The accreted material can therefore remain on the WD,
driving its mass closer to the Chandrasekhar limit, rather than being
blown off in a nova. OR CAN IT? Classical symbiotics experience
outbursts typically every 10 - 20 years, and these events are not
well-understood. After the 1985 outburst of the class prototype, Z
Andromedae (which is also a 28-minute pulsar), it appeared that a
shell of material had been ejected from the WD. This object has
recently outburst again. An X-ray observation within roughly one month
will provide v, T, and density diagnostics deep wit

Sequence Number: 900066

Sequence Number: 400112

Title : OBSERVATIONS OF A BLACK HOLE CANDIDATE X-RAY TRANSIENT DURING OUTBURST
DECAY
PI: Tomsick
Abstract: We propose to observe the black hole candidate (BHC) X-ray transient
XTE J1550-564 during outburst decay. We have been observing the decay
of the current outburst with RXTE, and, if the source flux continues
its current exponential decay, it will fall below RXTE detection
limits around 2000 July 16. Chandra observations after July 16 will
provide, for the first time, complete coverage of a BHC X-ray
transient decay from outburst to quiescence. Measurements of the flux
and the energy spectrum will address the question of whether there are
major changes in the accretion geometry as the source decays into
quiescence or if the change in X-ray flux is simply due to a drop in
the mass accretion rate. Such information has important implications
for ADAF models, which predict a large change in th

Sequence Number: 400111

Sequence Number: 700266

Title : X-RAYING THE BRIGHTEST AGN IN THE SKY WITH THE CHANDRA GRATINGS
PI: Fruscione
Abstract: We propose to observe the BLLac Mrk421 as a TOO whenever it reaches an
ultra-high state (2-12 keV flux greater than 20 mCrab). Currenty,
Mrk421 is undergoing a huge flare with a peak flux of 43 mCrab, making
it the brightest AGN in the sky. The flux has reached such a high
level (which is a factor of ~3 higher that the average) at only one
other time in the past 4 years. High spectral resolution Chandra HETG
and LETG X-ray observations of an AGN in such a bright state would
represent an extraordinary opportunity to study in great detail not
only the gaseous environment surrounding the nucleus, but also the
physical state of possible intervening absorption systems. We we will
be allowed to measure with extreme precision, the ionization degree,
the column density, the temperature, the densi

Sequence Number: 700265

Sequence Number: 300041

Title : CHANDRA HETG SPECTROSCOPY OF EX HYDRAE
PI: Howell
Abstract: EX Hya is an eclipsing intermediate polar-type CV with strong H- and
He-like K alpha emission lines of Mg, Si, S, Ar, and Fe emission lines
of Ne VII-VIII and Fe XVIII-XXIII in the EUV spectrum. The density of
the emitting plasma of EX Hya is ~ 10^13 to 10^15 cm^-3, more than an
order of magnitude greater than that of the corona of cool stars. We
propose a 60 ks Chandra HETG spectrum of EX Hya to: (1) constrain the
run of density with temperature (thereby constraining models of the
accretion column), (2) measure the amount of fluor- escence from the
irradiated surface of the WD, (3) measure elemental abundances
(controversial from the ASCA spectrum), and (4) spectroscopically
measure the density of the emitting plasma (via line ratios of He-like
O VII, Ne IX, Mg XI, Si XIII, S XV, Ar XVII

Sequence Number: 400110

Title : CHANDRA ACIS/LETG OBSERVATIONS OF THE LEAST ABSORBED X-RAY NOVA: XTE
J1118+48
PI: McClintock
Abstract: SCIENCE RATIONALE We propose Chandra grating observations of the X-ray
nova XTE J1118+48. The source was discovered in late March of this
year by the All-Sky Monitor on RXTE (IAUC 7389) and it was identified
optically shortly thereafter (IAUC 7390). This probable black-hole
source has a unique and important characteristic: It is the only X-ray
nova (XRN) located at high galactic latitude (b=+62 deg). Thus it has
by far the lowest extinction of any XRN, making it an exciting target
for grating studies with Chandra. The column density out of the plane
in this direction is log(NH) = 20.1 (Dickey and Lockman 1990, A&AS 28,
215). At energies <1 keV very little is known about the properties of
X-ray binaries--especially XRN--because nearly all sources lie at low
galactic latitude and have high

Sequence Number: 700202

Title : STUDIES OF RADIO JETS AND THE NARROW LINE REGIONS
PI: Wilson
Abstract: The X-ray emission of radio jets and of the narrow line regions of
active galaxies will be investigated with AXAF. Images and spectra
will be obtained to define the morphologies, X-ray powers, emission
mechanisms and physical conditions of both unresolved nuclear and
extended emission. Detection of non-thermal X-rays (inverse Compton or
synchrotron emission) will probe the properties of the magnetic fields
and cosmic ray spectra. If thermal X-ray emission is detected, the
density, temperature and chemical abundances of hot gas can be derived
and the relationship to other components (radio emission, narrow line
region) studied. Hot gas can be associated with hot radiatively driven
winds, shocks driven by mass outflow or cooling accretion flows.

Sequence Number: 400093

Title : TOO OBSERVATION OF THE RELATIVISTIC JET SOURCE CYGNUS X-3
PI: McCollough
Abstract: In Feb 1997, during a major radio flare in Cyg X-3, a 120
milli-arcsecond radio jet, which exhibited relativistic (~0.9 c)
expansion, was observed. Although Chandra would be unable to resolve
such a jet, a high-resolution spectra taken during a major flare may
contain Doppler shifted emission lines revealing the presence of an
x-ray jet. Observations of Cyg X-3 during such a flare offers the very
interesting possibility of studying the dynamics of jet formation and
propagation through the study of emission lines with the high spectral
resolution afforded by the HETG/ACIS SI configuration. The 20 ks
length of the observation permits coverage over one complete 4.8 hour
cycle. A second 20 ks observation 3 days later provides data for
studying the spectral evolution that surely accompanies su

Sequence Number: 400092

Sequence Number: 300037

Title : BZ CAM - A TRANSIENT SUPERSOFT X-RAY SOURCE?
PI: Di Stefano
Abstract: BZ Cam is a binary with a 221 min. period. It contains an accreting
white dwarf and a 0.3-0.4 solar mass main-sequence donor. BZ Cam
belongs to the group of variables called VY Scl stars. Most of the
time it spends at V=12.7 mag, but during low states it has V=14.3 mag.
BZ Cam is surrounded by a faint emission nebula (AA 181, 373).
Photoionization by a canonical cataclysmic variable cannot account for
the nebular excitation (emission line ratios). The proposed ACIS-S
observation will test the hypothesis that BZ Cam, like V751 Cyg (A&A
343, 183) and the canonical supersoft source (SSS) RX J0513.9-6951,
emits luminous supersoft X-rays during its optical low-state. If
supersoft X-rays could be detected, it would have 2 major
implications: (1) Discovery of new object class: VY Scl stars = tra

Sequence Number: 500093

Title : SURVEYING THE AFTERMATH OF A STARQUAKE
PI: Helfand
Abstract: The Vela pulsar underwent a sudden spinup yesterday morning (Jan 16.3
UT), the largest such event in the thirty years since its discovery.
We propose to take advantage of this fortuitous event by observing the
pulsar and its surrounding synchrotron nebula three times with the
Chandra HRC with the goals of 1) discriminating among models for such
spinup events, 2) constraining the equation of state of neutron star
matter, and 3) monitoring the effects of the event on the surrounding
synchrotron nebula. The Vela nebula will produce a count rate of ~3.8
c/s in the HRC-I, and the pulsar's pulsed emission should yield ~ .15
ct/s. Observations of 50 ksec duration will thus yield sensitivities
to a 1% change in the nebula (4 sigma) and a change of 15% in any of
20 phase bins for the pulse (3 sigm

Sequence Number: 300037

Sequence Number: 570470

Title : FOLLOW-UP OBSERVATIONS OF SN1999GI IN NGC 3184
PI: Schlegel
Abstract: Type II supernovae may all be X-ray sources but differences in
behavior are becoming visible: normal SN II's fade quickly while the
abnormal SN IIn's last for months, perhaps years. These suppositions
are based upon very limited statistics: 2 normal SN II's and about 4-6
SN IIn's. The turn-on times are unknown, as are the half-lives. Two
normal SN II's observed in the X-ray band are SN1980K (Canizares et
al. 1982) and SN1999em (Fox & Lewin 1999, IAU Circ 7318). The turn-on
time of these SNe appear to be nearly immediate. Radio and X-ray
emission should be correlated, yet are not: SN1980K was an early radio
source; SN1999em has not yet been detected. But a correlation with
radio emission must be suspect with so little data. SN1999gi,the
target of this TOO, represents a potential third norm

Sequence Number: 100011

Title : NULL
PI: WAITE
Abstract: NULL

Sequence Number: 100011

Title : NULL
PI: WAITE
Abstract: NULL

Sequence Number: 100010

Title : NULL
PI: WAITE
Abstract: NULL

Sequence Number: 402520

Sequence Number: 503447

Sequence Number: 503446

Sequence Number: 503445

Sequence Number: 402291

Title : The brightests ever X-ray burst from the nearest LMXB
PI: in 't Zand
Abstract: Cen X-4 is a transient LMXB that was last seen active in 1979. It is
the nearest LMXB, at 1.2 kpc. Therefore, it's brightness when active
is exceptional. This presents among others a unique opportunity to
measure in high spectroscopic detail radiation from the neutron star
surface, through thermonuclear X-ray flashes (or 'type-I X-ray
bursts'). The brightest ever X-ray burst, as well as the first ever,
was detected from this LMXB at the start of an outburst in 1969, at
50-60 Crab peak flux (Kuulkers, in 't Zand & Lasota 2009). We would
like to measure the high-resolution spectrum of a burst from Cen X-4
with the HETGS to search for narrow spectral features and possibly
constrain the compactness of the accreting neutron star through
measurement of the gravitational redshift. We aim again for an X-ray
burst at the start of an outburst, when there is less background from
the accretion radiation from the same source, when the burst is more
likely to burst and the burst is more fluent.

Sequence Number: 704253

Title : The recurring rebrightening of ESO253-G003
PI: Payne
Abstract: We discovered highly atypical rebrightenings within the galaxy
ESO253-G003. Numerous rebrightening events are highly unusual for an
AGN, which normally vary at a low-level following a damped random walk
model. Although other AGN such as IC 3599 have exhibited repeated
brightening episodes thought to be due to accretion disk
instabilities, this large number of brightening episodes is unique.
Studying this object will provide new and distinctive insights into
the mechanisms driving AGN and the broader inner workings of AGN
variability.

Sequence Number: 704252

Sequence Number: 201346

Sequence Number: 201345

Sequence Number: 402116

Title : ZTF18abfzgpl
PI: Ofek
Abstract: ZTF18abfzgpl is a faint/fast transient detected by ZTF on 12-Jul-2018.
It resembles the optical/radio/X-ray source associated with the
gravitational wave event GW170817. The transient was detected in a
star-forming galaxy at 240 Mpc. It had rise time <1 day, peaking at
abs. mag. of -17, and decayed by over 2.5 mags in the next three days.
A spectrum obtained during the first night shows a 15kK black-body
spectrum. As in the case of GW170817, the light curve and spectrum
suggest a low mass ejecta (~0.005 SM) moving at mildly relativistic
speeds (~0.3c). Followup of the source using the AMI radio telescope
at 15GHz shows a decaying radio source. On 2019 Feb 11 we observed the
source location with Swift-XRT for 9.5ks and found a faint source (3
cnt) with a false alarm probability smaller than 0.2%. The inferred
unabsorbed X-ray luminosity is about 10^41 erg/s. Given the high
velocity of the ejecta, as well it low mass, we speculate that a NS is
involved (e.g., a NS merger, or an AIC).

Sequence Number: 201085

Title : Coordinated calibration observation of Capella with Hitomi
PI: Petre
Abstract: Hitomi is just about to start its calibration phase. One of the most
critical SXS calibration targets is Capella, which will be used to
verify the low energy spectral resolution, line spread function, and
effective area. We request a coordinated Chandra HETG observation to
provide an absolute reference. Comparison with the well-calibrated
HETG will allow the SXS team to separate detector properties from
astrophysical effects. A simultaneous observation is needed to provide
an external measurement of the flux of Capella's lines, which are
known to vary in flux. Capella is the only Hitomi calibration source
for which a coordinated Chandra observation will be requested. A 60 ks
observation will allow us to cover entirely at least one of the 30 ks
pointings that Hitomi plans to perform on Capella during the
aforementioned window.

Sequence Number: 201085

Sequence Number: 401687

Sequence Number: 200829

Sequence Number: 401296

Title : The peculiar BH transient MAXI J1659-152: jet-only emission in
quiescence?
PI: Jonker
Abstract: The BH transient, MAXIJ1659-152, started decaying towards quiescence
before all X-ray observatories could no longer observe the source due
to Sun constraints. However, recent Swift observations (Yang et al.
2011 ATel 3201) found the source at a flux of 2E-11 cgs. This is
peculiar as all transient BHs except SwiftJ1753 decayed quickly.
During the last Swift observation the source was still at that flux
level and evidence for a line-like feature at 7.4 keV was found (by
us). Perhaps the source is in fact in quiescence, and what we observe
is X-ray emission from the jet impact region, the 7.4 keV line could
then be due to blueshifted Fe emission. A similar effect has been seen
in SS433 (Migliari et al. 2002). Furthermore, the source X-ray
position determined by Swift is somewhat shifted wrt the best known
VLBI radio emission. However, a short 1 ks Chandra observation will
shed light on this.

Sequence Number: 900939

Sequence Number: 900936

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 900737

Title : The Chandra Deep Field-South Survey: A Public Chandra Legacy
PI: Tananbaum
Abstract: Director's Discretionary observation to increase the exposure on the
CDFS from 1Msec to 2 Msec

Sequence Number: 200461

Sequence Number: 300182

Sequence Number: 300181

Sequence Number: 300180

Sequence Number: 500684

Title : GRB051022--Localization of a Candidate High Redshift Gamma-ray Burst
PI: Ricker
Abstract: Based on the observed characteristics of GRB050904, at z=6.29, it is
anticipated that high redshift (z>6) GRBs will be characterized by
long durations, of order ~30s*(z+1). Also, GRB050904 was very bright:
S ~ 5 x 10^-6 ergs cm-2. A GRB with several characteristics in common
with GRB050904 has been discovered and localized by HETE to ~2 arcmin
accuracy (GCN4131). The HETE source, GRB051022, has flux comparable to
GRB050904, and is exceedingly long (~300 s), consistent with z>6. No
prompt optical counterpart was detectable at a limit of R>20
(GCN4134). A followup observation by the Swift XRT established an
X-ray afterglow (XAG) and refined the HETE localization to ~10 arcsec.
In order to obtain an <1 arcsec localization of GRB051022, we propose
ACIS-S observations of the X-ray afterglow. Only Chandra can provide
such an accurate XAG position. Furthermore, the history of GRB
research has repeatedly shown that <1" localizations are essential to
confidently identify a host galaxy.

Sequence Number: 200365

Sequence Number: 200364

Sequence Number: 100052

Sequence Number: 500414

Sequence Number: 400269

Title : AN ACIS LOOK AT MACHO-99-BLG-22:AN INTERMEDIATE MASS BLACK HOLE ON OUR
DOORSTEP?
PI: Reynolds
Abstract: We request a 20ks ACIS-S observation at the position of the longest
ever detected microlensing event, MACHO-99-BLG-22. A likelyhood
analysis of the lensing event shows that the lens is either a stellar
mass black hole (BH) in the Galactic bulge, *or* an intermediate mass
BH about 500pc from us. Constraints from an old ROSAT-PSPC observation
are uninteresting (F_X<2*10^-13 erg/cm^2/s). However, Chandra will be
able to easily detect radiatively-efficient Bondi-Hoyle accretion onto
the BH. Even in the "worst case" of accretion from the hot ISM with a
column density of 1e21/cm^2 and a bolometric correction of 10, we
would expect to detect 20 photons. On the other hand, it is very
unlikely that a stellar mass BH in the bulge would be detectable. The
requested observation, therefore, provides a powerful way of
determining whether the lensing object really is an intermediate mass
BH on our doorstep.

Sequence Number: 500299

Sequence Number: 400245

Sequence Number: 400244

Sequence Number: 400243

Sequence Number: 400242

Sequence Number: 400241

Sequence Number: 400240

Sequence Number: 100033

Sequence Number: 500290

Title : AN EARLY OBSERVATION OF A NEARBY SUPERNOVA
PI: Schlegel
Abstract: The X-ray emission of supernovae is a young field with relatively
little data. The possible connection of supernovae with GRBs has been
tantalizing since the occurrence of SN1998bw. The debate over that
source continues. Observations of SN2002ap may go a long way to
settling some of the debate. In addition, the X-ray emission of Type
Ic supernova other than SN1998bw is based on the single detection of
SN1994I in M51. X-rays provide information about the circumstellar
ejecta as the out- going shock runs into matter from previous phases
of mass loss. A reverse shock is created which generates low-energy
X-rays (~1 keV) while the outgoing shock generates harder events. The
X-rays probe the circumstellar matter and will provide measures of
abundances. The X-ray light curve provides a measure of the matter
distribution. (Ref for SN: Schlegel 1995, Reports Prog in Physics, 58,
1375)

Sequence Number: 500289

Sequence Number: 500288

Sequence Number: 300088

Sequence Number: 700614

Sequence Number: 700613

Sequence Number: 700611

Sequence Number: 700610

Sequence Number: 700609

Sequence Number: 100027

Title : X-RAY EMISSION FROM COMET 10P/BORRELLY DURING THE DEEP SPACE 1
ENCOUNTER
PI: Dennerl
Abstract: X-ray emission from comets is now a well established phenomenon.
During the last years a lot of evidence has emerged that the dominant
mechanism is charge exchange between heavy solar wind ions and
cometary neutrals. The recent Chandra ACIS-S observation of Comet
C/1999 S4 (LINEAR) has provided the final proof. Measurements of solar
wind parameters, however, have never been made sufficiently near to a
comet to allow a direct comparison with the X-ray flux. The recent
decision of NASA to extend the Deep Space 1 mission for a rendezvous
with comet 19P/Borrelly in Sept 2001 opens, for the first time ever,
the unique opportunity to combine in-situ measurements of the solar
wind properties at a comet with simultaneous X-ray observations. This
RfO is submitted as a request for DDT since the dec

Sequence Number: 100027

Sequence Number: 300064

Sequence Number: 300063

Sequence Number: 300062

Sequence Number: 300055

Sequence Number: 500202

Sequence Number: 500201

Sequence Number: 500198

Sequence Number: 400113

Last updated: 11/17/24

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