CalDB Public Release Notes Version 3.2.1 Effective Date: 2005-12-15T16:00:00 For public, internal, and SDP release as soon as possible. I. Introduction CalDB 3.2.1 is a public release CalDB upgrade which is a patch to version 3.2.0. It includes HRMA axial effective area, HRC-S QE, HRC-I RMF, HETG GREFF, and ACIS non-CTI-corrected default gain files for -120C ACIS temperature. It also includes the PIMMS FITS files, which are only used for proposal planning builds internally, but they are included in the distribution for version consistency. (Users do not any longer ever use PIMMS FITS files.) User documentation that will be extremely handy for dealing with the new CalDB is available at "CALDB 3.2.1: HRMA Effective Area" http://cxc.harvard.edu/ciao3.3/why/caldb3.2.1_hrma.html "CALDB 3.2.1: HRC-I RMF" http://cxc.harvard.edu/ciao3.3/why/caldb3.2.1_hrci_rmf.html and "How CalDB 3.2.1 Affects Your Analysis" http://cxc.harvard.edu/ciao3.3/releasenotes/ ciao_3.3_release.html#HowCALDB3.2.1AffectsYourAnalysis II. Summary of Changes A. ACIS -120C non-CTI-corrected DET_GAIN N0005 Location: $CALDB/data/chandra/acis/bcf/gain/ Filenames: acisD2000-01-29gainN0005.fits acisD2000-07-04gainN0005.fits acisD2000-07-06gainN0005.fits acisD2000-08-12gainN0005.fits The default gain files for ACIS DATAMODE=GRADED observations have been upgraded to include the newest gain tables for the BI chips only. This will present a significant improvement in order-sorting results for S1 when gratings are in use. However users will be directed hereafter to employ the new phase 2 response generator "mkacisrmf" for these data in the future, as the new gains are not compatible with the old non-CTI FEF files (inputs for "mkrmf"). Pipes/tools affected: SDP: ACIS L1 processing "acis_process_events" CIAO: ACIS reprocessing tool "acis_process_events" Threads affected: "Applying an ACIS Gain Map" http://cxc.harvard.edu/ciao/threads/acisgainmap/ "Create a New Level=2 Event File" http://cxc.harvard.edu/ciao/threads/createL2/ "Generating ACIS Responses with mkacisrmf" (BI CHIPS ONLY for GRADED MODE) http://cxc.harvard.edu/ciao/threads/mkacisrmf/ B. HRMA Axial Effective Area N0007 Location: $CALDB/data/chandra/tel/hrma/bcf/effearea/ Filename: hrmaD1996-12-20axeffaN0007.fits It has been presented at various Chandra Calibration Workshops that a small but significant residual exists in the Iridium M abosrption edge energy range (2.1-3 keV) in the spectra of certain broad-band continuum sources such as blazars, where the spectra are not heavily piled up. A modification of the HRMA model has been introduced, which includes a very thin 22A coating of hydrocarbon, in order to reduce these Ir residuals significantly. The addition of the overlayer, however, increases the HRMA effective area by ~5-7% over most of the Chandra bandpass, and in the M-edges the increase is 10-16%. Technical details and information links are below. Pipes/tools affected: No SDP pipes use the HRMA axeffa. CIAO: mkarf, mkwarf, mkgarf, mkinstmap Threads affected: "Weighting ARFs and RMFs: multiple sources (mkwarf)" http://cxc.harvard.edu/ciao/threads/wresp_multiple_sources/ "Extract ACIS Spectra for Pointlike Sources and Make RMFs and ARFs" http://cxc.harvard.edu/ciao/threads/psextract/ "Compute HETG/ACIS-S Grating ARFs" http://cxc.harvard.edu/ciao/threads/mkgarf_hetgacis/ "Imaging" threads under: http://cxc.harvard.edu/ciao/threads/imag.html C. HRC-S AIMPOINT QE N0008 Location: $CALDB/data/chandra/hrc/bcf/qe/ Filename: hrcsD1999-07-22qeN0008.fits The HRC-S QE, which is deconvolved from the LETGS effective areas along with the QEU, has been adjusted to accommodate the new HRMA axial effective area (Item B above). The result is that the HRC-S and LETG/HRC-S effective area configurations will see no change in the calculated ARFs or GARFs from CIAO when both HRMA v7 and HRC-S QE v8 are installed, as they will be in CalDB 3.2.1. Pipes/tools affected: CIAO tools as follows. mkexpmap (mkinstmap) for HRC-S Threads affected HRC-S mkexpmap under "Imaging" http://cxc.harvard.edu/ciao/threads/imag.html "Compute LETG/HRC-S Grating ARFs" http://cxc.harvard.edu/ciao/threads/mkgarf_letghrcs/ D. HETG Grating Efficiency (GREFF) N0005 Location: $CALDB/data/chandra/tel/grating/hetg/bcf/greff/ Filename: hetgD1996-11-01greffpr001N0005.fits Small but significant adjustments to the pos and neg first order gains for HEG and MEG have been included in this new dataset, which the HETG team finds remove certain consistent residuals in the fits of HETG/ACIS-S spectra. The changes had to be deconvolved between the HEG and the MEG, once the new HRMA axeffa model was made available. Pipes/Tools Affected: SDP: NONE CIAO: mkgarf with HEG or MEG, order=+/-1 only Theads Affected: "Compute HETG/ACIS-S Grating ARFs" http://cxc.harvard.edu/ciao/threads/mkgarf_hetgacis/ E. HRC-I RMF N0001 Location: $CALDB/data/chandra/hrc/cpf/rmf/ Filename: hrciD1999-07-22rmfN0001.fits Now that the HRC-I gain maps have been installed in processing (DS 7.6.4, CalDB 3.2.0), a useful HRC-I RMF has been produced to analyze the resulting PI distributions in order to calculate spatially-invariant hardness-ratios and quantile color-color maps of HRC-I observations. The HRC-I team recommends against attempting spectral fitting with this RMF because the spectral resolution of the instrument is insufficient for this purpose. Also note that the energy scale defining the PI bin boundaries is not monotonic for the HRC-I and therefore the EBOUNDS extension included in this file is deliberately set to be meaningless. Pipes/tools affected: SDP: NONE CIAO: sherpa, when used to derive quantile color-color images Threads affected: TBD: Instructions for making the quantile color-color maps are forth-coming. F. PIMMS Cycle 08 Effective areas (N0008) Location: $CALDB/data/chandra/acis/cpf/pimms/ Filenames: acisiD2005-11-30pimmsN0008.fits acissD2005-11-30pimmsN0008.fits Location: $CALDB/data/chandra/hrc/cpf/pimms/ Filenames: hrciD2005-11-30pimmsN0008.fits hrcsD2005-11-30pimmsN0008.fits Location: $CALDB/data/chandra/tel/grating/hetg/cpf/pimms/ Filenames: acisihetg0D2005-11-30pimmsN0008.fits acissheg1D2005-11-30pimmsN0008.fits acisshegmeg1D2005-11-30pimmsN0008.fits acisshetg0D2005-11-30pimmsN0008.fits acissmeg1D2005-11-30pimmsN0008.fits Location: $CALDB/data/chandra/tel/grating/letg/cpf/pimms/ Filenames: acisiletg0D2005-11-30pimmsN0008.fits acissleg1D2005-11-30pimmsN0008.fits acissletg0D2005-11-30pimmsN0008.fits hrciletg0D2005-11-30pimmsN0008.fits hrcsleg1D2005-11-30pimmsN0008.fits hrcsleghiD2005-11-30pimmsN0008.fits hrcsletg0D2005-11-30pimmsN0008.fits Users are encouraged to ignore these files. They are no longer used by the CIAO proposal planning tool "prop_pimms," because they are instead loaded into the patch file for CIAO 3.3.0.1. The above upgrades for HRMA, HETG, and HRC-S are all employed in the production of the PIMMS Cycle 08 effective area files. Pipes/tools affected: NONE Threads affected: NONE ----------------------------------------------------------------------------- III. Technical Details A. ACIS -120C non-CTI-corrected DET_GAINs N0005 It has been realized that the BI chip gains for the non-CTI (-120C) case have not been upgraded to the most recent, best BI chip gain models, which are currently already used in the CTI-correction path. The important point here is that BI chips are not yet actually CTI corrected in Standard Data Processing (SDP) or in CIAO A-P-E reprocessing. However, there is still a new gain function for both chips, and this is a significant improvement for the case of BI chip ACIS-S1. For ACIS-S3 the upgrade isn't as striking or as important, but it might as well be included in the proposed change. The FI chip gains will remain the same as before. However, all of the CalDB ACIS Gain files include data for all 10 chips at once, so only one file is selected for any given case. One implication for this change will be that FOR BI CHIPS ONLY, with DATAMODE=GRADED, the users doing imaging spectroscopy (who need to calculate RMFs) will need to use the "mkacisrmf" path, rather than the non-CTI-corrected FEFs and mkrmf. The "gain" parameter in "mkacisrmf" must be set to the same filename as is in the L2 EVENTS file header under the GAINFILE keyword. (Using the WMAP option in mkacisrmf, this will happen automatically.) However, for the FI chips in GRADED DATAMODE, the CTI corrector will not have been applied, and so those responses must be generated using mkrmf with a non-CTI-corrected -120C FEF. Hence the imaging spectral analysis thread of GRADED mode data will have to be bifurcated now, based on the whether you are dealing with BI chip or FI chip data. The procedure to produce the new dataset was as follows: 1. Took the acisD2000-01-29gain_ctiN0005.fits file and altered it for this purpose, by reducing the length of the PHA, ENERGY, and SIGMA column vectors from 89 to 47, in order to make the modified version of this file commensurate with the non-CTI dataset. The result is the file acisD2000-01-29gain_ctiN0005mod.fits. 2. Used the command $> dmmerge infile=@merge.lis outfile=acisD2000-01-29gainN0005.fits where merge.lis is: $> more merge.lis acisD2000-01-29gainN0004.fits[2][ccd_id=0:4,6,8:9] acisD2000-01-29gain_ctiN0005mod.fits[2][ccd_id=5,7] 3. Verify checksums and with fverify. 4. Copies of the acisD2000-01-29gainN0005.fits file were made to each of the filenames acisD2000-07-04gainN0005.fits acisD2000-07-06gainN0005.fits acisD2000-08-12gainN0005.fits The Calibration Validity Start Date and Time keywords (CVSD0001 and CVST0001) were set as follows: FILENAME CVSD0001 CVST0001 acisD2000-01-29gainN0005.fits 2000-01-29T20:00:00 20:00:00 acisD2000-07-04gainN0005.fits 2000-07-04T06:00:00 06:00:00 acisD2000-07-06gainN0005.fits 2000-07-06T21:00:00 21:00:00 acisD2000-08-12gainN0005.fits 2000-08-12T22:00:00 22:00:00 B. HRMA Axial Effective Area N0007 It has been noted that a statistically significant residual exists in fitting certain broad band continuum sources (e.g. blazars) that is due to the depth of the iridium M-edges in the HRMA effective area relative to what these instrumental spectra exhibit at 2.1 keV. Until now, no contamination layer has been included in the HRMA model, though it has long been suspected that there must be some non-zero level of hydrocarbon accumulation on the mirror elements, given their history. It has been found that a 22A overlayer of 1g/cm^3 hydrocarbon will minimize the Ir M-edge residuals for a group of these continuum, not heavily piled-up sources. The details of the derivation are included in a memorandum by H. Marshall, visible at http://space.mit.edu/ASC/calib/heg_meg/meg_heg_report.pdf In particular Fig. 3 illustrates the composite of residuals from fits to 13 blazar spectra. Fig. 6 illustrates the minimization with HRMA overlayer depth at 22 anstroms. In addition, new Iridium (Ir) optical constants have been delivered from the former AXAF Synchrotron scientist (D. Graessle) which include experimental optical constants covering the 50-1000 eV range, with some refinement of the Ir optical constants in the M-edge range. The essential change here is that the new optical constants have been derived considering several mirrors (3-16 mirrors, in fact) rather than only one, as in the previous data sets. This introduces some additional small features in the HRMA EA below 1 keV, most significantly at the Ir N74f7/2(60.8 eV) and N64f5/2(63.8eV) edges, and the N34p3/2(495.8 eV). There is also a somwhat different shape to the curve between these edges than in the Henke 1993 Iridium optical constants used in the earlier axial effective area files (versions N0006 and earlier). These HRMA effective area (EA) predictions are based upon the HRMA model orbit_XRCF+tilts+ol_01 which improves upon the previous official model (orbit_XRCF+tilts_04) by the inclusion of * new Ir optical constants (from Dale Graessle et. al) * a 22A layer of CH2 on top of the Ir layer, simulating contamination of the optic * Experimental uncertainties based upon the XRCF measurements of the effective area using FPC and SSD detectors (from Ping Zhao) C. HRC-S AIMPOINT QE N0008 The LETGS effective areas are determined via cross calibrations between cosmic sources and prelaunch measurements, following an involved procedure, which is due to post-calibration adjustments and post launch performance issues. The HRC-S QE and QEU are then backed out the LETGS EA by successively removing the LETG grating efficiencies and the HRMA effective areas by shell. Hence, if either of the LETG GREFF or HRMA models change, the HRC-S QE must be adjusted accordingly, unless there is an independently verified need to adjust the overall LETGS effective area. Because of the upgrade to the HRMA AXEFF (Item II.B.), there is now an incumbent, simultaneous change to the HRC-S QE required. (The QEU is fine left as is for a HRMA axial effective area update.) The incumbent change required here is to absorb the entire HRMA modification into the QE so as to produce no net change in the LETGS effective areas, for any of the zeroth, first, or higher orders. This change will also produce an essentially identical HRC-S aimpoint effective area. D. HETG Grating Efficiency (GREFF) N0005 From H. Marshall (MIT/Kavli/HETG team) 14 October 2005 "I [have derived] updates tot he HETGS grating efficiencies. When combined with other effective area updates, such as the HRMA Ir-M edge (See Item II.B.), accounting for contamination, and correcting for a residual Si-K edge, I obtain very good residuals for simple fits to the spectra of many blazars. The updates are somewhat ad hoc and the apportionment of the mismatch of the MEG and HEG spectra is determined empirically. The result is that relative uncertainties should now be less than 5% across the HETGS band from 0.5 to 8 keV." The changes are in only the +/- first orders of the HEG and MEG grating efficiency data (GREFF). A full report of the change is given in the memorandum http://space.mit.edu/ASC/calib/heg_meg/meg_heg_report.pdf In particular, Fig. 12 of this paper illustrates the specific adjustments made to the HEG and MEG first order efficiencies. Note that there is a transition at 15 A, below which (in wavelength) the correction factor is predominantly to the MEG, while at higher values (lower energies) it is the HEG correction factor that dominates. The greatest deviation from unity for the MEG factor is -8% broadly about 11A, while for the HEG it is +12% at 17.5A. E. HRC-I RMF N0001 We have developed an RMF for the HRC-I. The intrinsic energy resolution of the HRC is poor compared with the ACIS, but it does have some ability to discriminate between hard and soft spectra. Lab tests of HRC-I pulse-height distributions obtained during sub-assembly calibration show a monotonic trend in the median PHA for line energies below 2 keV (see Figure 7.7 of the Chandra Proposers' Observatory Guide http://asc.harvard.edu/proposer/POG/html/HRC.html#fg:hrc-pha.) This spectral discrimination is also seen in flight data. We have analyzed data from the flaring variable coronal source AR Lac, which has been regularly observed since 1999 as a calibration source to monitor the HRC-I gain and QE, and in the adjacent plot we show the count-rate and the corresponding median PI computed for each observation (each approximately 2 ks in duration) with off-axis values < 8 arcmin. When a coronal source flares, the plasma temperature is usually higher, and consequently the spectrum is harder; a (weak) correlation is therefore to be expected between count-rate and spectral hardness, and is indeed detected in the data. A correlation of 0.27 is observed, with an error of 0.02 determined after a Monte Carlo simulation of the individual errors. Pearson's coefficient rho is 0.24, with a p-value of 0.02, and Kendall's Rank correlation coefficient tau is 0.17, with a p-value of 0.01. Using observations of HR1099 carried out using the HRC-I/LETG at various locations on the detector (ObsIDs 1388, 1389, 1392, 1393), we have constructed a response matrix for the HRC-I (see Kashyap & Posson-Brown 2005). This can be used to calibrate hardness ratios or quantile color-color diagrams (QCCD) to distinguish between gross differences in the spectra. We recommend the QCCD, as it is relatively less dependent on temporal variations in the gain that are known to exist, and are not yet accounted for, in the gain-correction maps. See the web page "HRC-I RMF" at http://cxc.harvard.edu/cal/Hrc/RMF/index.html for more background on the new file. F. PIMMS Cycle 08 Effective areas (N0008) See the CalDB proposal planning pages at "Cycle 08 PIMMS Effective Areas" http://cxc.harvard.edu/caldb/prop_plan/pimms/index.html and "Cycle 08 PIMMS Effective Area Public Information" http://cxc.harvard.edu/caldb/prop_plan/pimms/pimms.html for details about the construction of these EA files.