Last modified: 2 December 2019

URL: https://cxc.cfa.harvard.edu/caldb/prop_plan/pimms/pimms.html

Cycle 22 PIMMS Effective Area Public Information

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Released as of 17 DEC 2019



The Chandra effective areas are built for sixteen configurations implemented in the PIMMS EA viewer and count rate calculator facility. Four of the configurations are for the default aim-point positions for each of the four detector arrays aboard Chandra, specifically the ACIS-I, ACIS-S, HRC-I and HRC-S routines.

The other twelve configurations involve one or the other of the transmission gratings. For the HETG/ACIS-S configurations the default SIM_Z positions do not correspond to the above aim point settings, but instead are offset to minimize the ACIS CTI effect. A default SIM_Z offset of -3.0 mm (in the direction of the readouts) is used for HETG/ACIS-S.

As in previous years, model observations have been selected so that the zeroth order ARFs, as well as the first order GARFs will correspond to the appropriate positions on the ACIS-S array. The same is true for the LETG/HRC-S configuration, where the default zeroth order position does not necessarily coincide with the default imaging aim point.

PIMMS effective area (EA) files are built using model observations (OBSIDs) with standard/default detector and SIM_Z configurations with the CIAO 4.11 routines mkarf for imaging aimpoint cases and mkgarf for gratings configurations, using the most current CALDB input files (CALDB 4.8.5). The following table gives the input CALDB file information used by mkarf or mkgarf to generate the respective effective area files (as ARFs) for the Cycle 21 (N0021) and Cycle 22 (N0022) proposal cycles. Plots of the PIMMS effective areas may be viewed at the PIMMS Effective Area Data page. You may also use the automated Chandra Effective Area Viewer.

PIMMS Input Data and Procedure Changes for Cycle 22:

CalDB Input File Uprades (since Cycle 21):

  1. AIMPOINT Configurations: ENERGY GRIDS All the grids for the aimpoint configurations match the default energy grid of the LETG first order for that detector array; for the HRC-I, the grid corresponds to the LETG/HRC-S first order default grid. Hence, for ACIS configurations, the aimpoint and zeroth order grids all have 8192 points. For HRC, the energy grids include 16384 points. The grids were changed for Cycle 21 in December 2018, to eliminate interpolation errors that occur when comparing spectra (and associated count rates) when comparing or calculating results across configurations.

  2. ACIS configurations: These have all been affected by the upgrade of the ACIS CONTAM file from version N0012 in Cycle 21 to N0013 in Cycle 22. The N0013 CONTAM file predicts a higher contamination level after the start of year 2018, which decreases the relative effective area. Additionally, the TIME delay qualifier for the effective areas has been adjusted for Cycle 22 to be 15 May 2021 UTC, or 737424069.184s MET. The result is that the Cycle 22 EAs for ACIS configurations show up to considerable decrease in predicted EA below 1 keV compared with Cycle 21, particularly for ACIS-I, and less strongly for ACIS-S. (ACIS-I has almost zero effective area at C-Kα, so the large decrease will have minimal affect on ACIS-I count rates. For ACIS-S, the low-energy effective area is significant, and hence, count rates derived for ACIS-S will be significantly decreased.) The difference decreases to 10% at 1 keV, and becomes negligible above 2 keV, as expected for the contamination effect.

  3. HRC-I configurations: Inasmuch as there have been no modifications or additions to the HRC-I radiometric calibrations, there is no change to the effective area curves for HRC-I configurations in Cycle 22 compared with cycle 21.

  4. HRC-S configurations: There have been two updates to the time-dependent QE Uniformity library for HRC-S from version N0010 series of QEUs to the version N0012 series, which includes two additional files with later effective dates. Naturally since PIMMS uses the latest file in the set for predictive EA purposes, these changes result in a minor change to the CY22 HRC-S EAs compared with the CY21 EAs. The effect is overall slightly less than 2.5 % across the full spectrum. Note that the HRC-S QEU is variable as a function of location along the length of the detector arrray, and is therefore wavelength-dependent.

Parameter Input Changes (versus CY21 inputs):

  1. Imaging aimpoints:Due to the thermal cycling of the Chandra Aspect Camera, the aimpoint drift has become irregular, and an operational scheme has been adopted to fix targets dynamically at the desired location. This results in a permanent aimpoint location for each chip as a matter of course (which may be changed programatically if necessary, but not due to drift. See the Table below, and the Proposers Observatory Guide (POG) Table 6.4. The permanent aim point locations were set for the Cycle 18 release, and remain so for the current cycle.

  2. ACIS CONTAM time-delay parameter: The CIAO ARF- and GARF-generating routines employ a time-delay option in the "detsubsys" parameter specification, wherein a TT date value in seconds may be entered to set the date for the time-dependent CONTAM calculations. For Cycle 22 the value is 737424069.184, which corresponds to UTC date 15 May 2021. For Cycle 21 the value was 705888069.184, corresponding to 15 May 2020. This affects all and only ACIS configurations.


TABLE 1

Configuration (CHIPX, CHIPY) ObsID Used HRMA QE QEU ACIS FI DEAD AREA ACIS CONTAM CONTAM TIME DELAY ACIS OSIP GREFF CALDB Filenames
ACIS-I (970.0, 975.0) 9768 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0012.fits
acisD1999-08-13contamN0013.fits
705888069.184
737424069.184
N/A N/A acisiD2018-11-20pimmsN0021.fits
acisiD2019-11-14pimmsN0022.fits
ACIS-S (210.0, 520.0) 9300 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0012.fits
acisD1999-08-13contamN0013.fits
705888069.184
737424069.184
N/A N/A acissD2018-11-20pimmsN0021.fits
acissD2019-11-14pimmsN0022.fits
HRC-I (7590.0, 7745.0) 8531 hrmaD1996-12-20axeffaN0008.fits hrciD2017-08-20qeN0011.fits hrciD1999-07-22qeuN0002.fits N/A N/A N/A N/A N/A hrciD2018-11-20pimmsN0021.fits
hrciD2019-11-14pimmsN0022.fits
HRC-S (2095.0, 8915.0) 9630 hrmaD1996-12-20axeffaN0008.fits hrcsD2012-03-29qeN0014.fits hrcsD2018-05-27qeuN0010.fits
hrcsD2019-02-24qeuN0012.fits
N/A N/A N/A N/A N/A hrcsD2018-11-20pimmsN0021.fits
hrcsD2019-11-14pimmsN0022.fits
HETG0/ACIS-I (970.0, 975.0) 9768 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0012.fits
acisD1999-08-13contamN0013.fits
705888069.184
737424069.184
N/A hetgD1996-11-01greffpr001N0007.fits acisihetg0D2018-11-20pimmsN0021.fits
acisihetg0D2019-11-14pimmsN0022.fits
HETG0/ACIS-S (211.2, 369.3) 7280 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0012.fits
acisD1999-08-13contamN0013.fits
705888069.184
737424069.184
N/A hetgD1996-11-01greffpr001N0007.fits acisshetg0D2018-11-20pimmsN0021.fits
acisshetg0D2019-11-14pimmsN0022.fits
HEG1/ACIS-S (211.2, 369.3) 7280 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0012.fits
acisD1999-08-13contamN0013.fits
705888069.184
737424069.184
acisD2000-01-29osip_ctiN0006.fits hetgD1996-11-01greffpr001N0007.fits acissheg1D2018-11-20pimmsN0021.fits
acissheg1D2019-11-14pimmsN0022.fits
HEGMEG1/ACIS-S (211.2, 369.3) 7280 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0012.fits
acisD1999-08-13contamN0013.fits
705888069.184
737424069.184
acisD2000-01-29osip_ctiN0006.fits hetgD1996-11-01greffpr001N0007.fits acisshegmeg1D2018-11-20pimmsN0021.fits
acisshegmeg1D2019-11-14pimmsN0022.fits
MEG1/ACIS-S (211.2, 369.3) 7280 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0012.fits
acisD1999-08-13contamN0013.fits
705888069.184
737424069.184
acisD2000-01-29osip_ctiN0006.fits hetgD1996-11-01greffpr001N0007.fits acissmeg1D2018-11-20pimmsN0021.fits
acissmeg1D2019-11-14pimmsN0022.fits
LETG0/ACIS-I (970.0, 975.0) 9768 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0012.fits
acisD1999-08-13contamN0013.fits
705888069.184
737424069.184
acisD2000-01-29osip_ctiN0006.fits letgD1996-11-01greffpr001N0007.fits acisiletg0D2018-11-20pimmsN0021.fits
acisiletg0D2019-11-14pimmsN0022.fits
LETG0/ACIS-S (210.0 520.0) 10662 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0012.fits
acisD1999-08-13contamN0013.fits
705888069.184
737424069.184
acisD2000-01-29osip_ctiN0006.fits letgD1996-11-01greffpr001N0007.fits acissletg0D2018-11-20pimmsN0021.fits
acissletg0D2019-11-14pimmsN0022.fits
LEG1/ACIS-S (210.0 520.0) 10662 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0012.fits
acisD1999-08-13contamN0013.fits
705888069.184
737424069.184
acisD2000-01-29osip_ctiN0006.fits letgD1996-11-01greffpr001N0007.fits acissleg1D2018-11-20pimmsN0021.fits
acissleg1D2019-11-14pimmsN0022.fits
LETG0/HRC-I (7590.0, 7745.0) 8531 hrmaD1996-12-20axeffaN0008.fits hrciD2017-08-20qeN0011.fits hrciD1999-07-22qeuN0002.fits N/A N/A N/A N/A letgD1996-11-01greffpr001N0007.fits hrciletg0D2018-11-20pimmsN0021.fits
hrciletg0D2019-11-14pimmsN0022.fits
LETG0/HRC-S (2116.9, 8850.3) 331 hrmaD1996-12-20axeffaN0008.fits hrcsD2012-03-29qeN0014.fits hrcsD2018-05-27qeuN0010.fits
hrcsD2019-02-24qeuN0012.fits
N/A N/A N/A N/A letgD1996-11-01greffpr001N0007.fits hrcsletg0D2018-11-20pimmsN0021.fits
hrcsletg0D2019-11-14pimmsN0022.fits
LEG1/HRC-S (2116.9, 8850.3) 331 hrmaD1996-12-20axeffaN0008.fits hrcsD2012-03-29qeN0014.fits hrcsD2018-05-27qeuN0010.fits
hrcsD2019-02-24qeuN0012.fits
N/A N/A N/A N/A letgD1996-11-01greffpr001N0007.fits hrcsleg1D2018-11-20pimmsN0021.fits
hrcsleg1D2019-11-14pimmsN0022.fits
LEGHI/HRC-S (2116.9, 8850.3) 331 hrmaD1996-12-20axeffaN0008.fits hrcsD2012-03-29qeN0014.fits hrcsD2018-05-27qeuN0010.fits
hrcsD2019-02-24qeuN0012.fits
N/A N/A N/A N/A letgD1996-11-01greffpr001N0007.fits hrcsleghiD2018-11-20pimmsN0021.fits
hrcsleghiD2019-11-14pimmsN0022.fits

Notes for Table 1:

None.

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