CALDB Public Release Notes Version: 2.18 CALDB Effective Date: 2002-11-08T00:00:00 PUBLIC RELEASE coincides with CIAO 2.3 release, scheduled for 08-NOV-2002. SDP installation 2002-11-08T00:00:00 (UTC). CIAO 2.3 or later is required for the proper use of CALDB 2.18. CALDB 2.18 or later is required for the proper function of CIAO 2.3. I. Summary of Changes A. ACIS CTI event correction table with trap density maps FILE LOCATION: $CALDB/data/chandra/acis/bcf/cti/ FILENAME: acisD2000-01-29ctiN0002.fits This is a new file. This file is used by CIAO/SDP tool acis_process_events when the CTI-correction switch is set to yes. Calibrations are immediately applicable for -120C ACIS data taken during year 2000. The time-dependence of these calibrations for later years has not yet been finalized or released. Contains CTI-correction calibrations for ACIS chips 0, 1, 2, 3, and 6 only. Currently these are the only chips for which the CTI correction has been calibrated for use in CIAO. B. ACIS PHA FEF for CTI-corrected response functions (PHA and PI) FILE LOCATION: $CALDB/data/chandra/acis/cpf/fefs/ FILENAME: acisD2000-01-29fef_pha_ctiN0001.fits This is a new file. For CTI-corrected -120 C events on ACIS chips 0, 1, 2, 3, and 6. Contains responses for non-CTI corrected data in the other five ACIS chips. C. ACIS gain for CTI-corrected events PHA-to-PI conversion FILE LOCATION: $CALDB/data/chandra/acis/bcf/gain/ FILENAME:acisD2000-01-29gain_ctiN0001.fits New file. Gains derived from the new CTI-corrected FEF file above (See I.B.) This gain file must be applied when reprocessing data with acis_process_events, applying the CTI-corrector. D. ACIS PHA FEFs for non-CTI-corrected responses (PHA and PI) FILE LOCATION: $CALDB/data/chandra/acis/cpf/fefs/ FILENAMES: acisD1999-07-22fef_phaN0002.fits acisD1999-08-13fef_phaN0002.fits acisD1999-09-16fef_phaN0002.fits acisD2000-01-29fef_phaN0003.fits These are upgrades from their previous version numbers. These files have an additional header keyword with allows PI RMFs to be derived from these PHA_FEF files. CIAO 2.3 or later is absolutely required for the use of these FEFs to make PI RMFs, because the dynamical rebinning capability of mkrmf has been added as of that version number. E. HRC Amp Scale Factor Correction (AMP_SF_COR) tables FILE LOCATION: $CALDB/data/chandra/hrc/bcf/amp_sf_cor/ FILENAMES: hrciD1999-07-22amp_sf_corN0001.fits hrcsD1999-07-22amp_sf_corN0001.fits These are new additions to the CALDB. These tables contain coefficients applicable to the amp scale factor correction algorithm in hrc_process_events (CIAO 2.3 or later, TBD in Standard Processing). II. Technical Details This section provides technical information and URLs to CAL web pages relevant to the data in the new CALDB files in question. A. ACIS CTI event correction table with trap density maps >From Glenn Allen (10/25/2002): The contents of the CTI ARD file include HDU 1: A table with the following columns Column Name Format Dims Units TLMIN TLMAX 1 CCD_ID I 2 CHIPX_LO I pixel 3 CHIPX_HI I pixel 4 CHIPY_LO I pixel 5 CHIPY_HI I pixel 6 NPOINTS I 7 PHA 47E adu 8 VOLUME_X 47E 9 VOLUME_Y 47E HDU 2: A trap-density map for CCD I0 HDU 3: " I1 HDU 4: " I2 HDU 5: " I3 HDU 6: " S2 The CTI adjustment to the data is performed by adding charge to each pixel of a 3x3 event island to improve the energy of the CCDs. The amount of charge added charge_added = trap_density * volume Here, the "trap_density" is the sum of the trap density in every pixel between the read out and the pixel where the event occurred. The values of trap_density are stored in the five images contained in HDUs 2-6. (Only five trap-density maps are provided because the ACIS-I and ACIS-S2 CCDs are the only ones whose parallel CTI has been calibrated so far.) The value of "volume" is obtained from the table in HDU 1. The volume is computed by finding the row in the table that has the right CCD_ID, CHIPX_LO, CHIPX_HI, CHIPY_LO, and CHIPY_HI values. In that row, the sets of PHA and VOLUME_Y points are used to compute the volume based on the PHA value for the CTI adjusted event. (The volume occupied by a charge packet is a function of the pulse height of the event.) A linear interpolation scheme is used between the tabulated pairs of PHA and VOLUME_Y points. Note that the VOLUME_X column is designed for use with a serial CTI adjustment. Since the effects of serial CTI have not been calibrated, this column is full of zeros at the moment. However, it remains in the file as a place holder in case the serial CTI is calibrated. CAL WEB PAGE: TBD Pipes/Software/Tools applicable: CIAO 2.3/SDP acis_process_events Threads affected: "Apply the ACIS CTI Correction" http://cxc.harvard.edu/ciao/threads/acisapplycti/ B. ACIS PHA FEF for CTI-corrected response functions (PHA and PI) The CIT-correction software in acis_process_events will be released with CIAO 2.3. Hence any associated analysis files will be required for using this new feature. The subject FEF file is the most essential element in that analysis. Currently, we have calibrations for -120C operations only, immediately applicable to the year 2000 operations. The time-dependency of the ACIS CTI-corrected response has yet to be calibrated, but further releases are expected. The file in question can be used for PHA and PI analysis (with dynamical rebinning). The file includes CTI-corrected responses for ACIS chips 0,1,2,3, and 6 (the FI chips of the usual ACIS-I imaging configration). It also includes non-CTI responses for the other five chips, for generality of application to data run through the CTI-correction software. CAL WEB PAGE: TBD Pipes/Software/Tools affected:CIAO 2.3 mkrmf, mkwarf, acis_fef_lookup Threads affected: "Extract ACIS Spectra for Pointlike Sources and Make RMFs and ARFs" http://cxc.harvard.edu/ciao/threads/psextract/ "Weighting ARFs and RMFs: multiple sources" http://cxc.harvard.edu/ciao/threads/wresp_multiple_sources/index.html "Extracting Extended Source Spectra and Responses" http://cxc.harvard.edu/ciao/threads/acisspec_extract/ C. ACIS gain for CTI-corrected events PHA-to-PI conversion CAL WEB PAGE: TBD Pipes/Software/Tools affected: CIAO 2.3/SDP acis_process_events Threads affected: "Apply the ACIS CTI Correction" http://cxc.harvard.edu/ciao/threads/acisapplycti/ D. ACIS PHA FEFs for non-CTI-corrected responses (PHA and PI) The CIAO 2.3 release will include a version of mkrmf which can generate PI RMFs from PHA FEFs by dynamical rebinning. A minor header change is required to enable this capability; there has been a reassignment of REGNUM (region number convention) in the BINTABLES, which does not affect RMF calculations in any way. Additionally, We have currently a difficulty in working with PI in our existing FEFs, namely that a one-channel shift (toward higher energies) occurs for all chips except S3, which works correctly. The new FEFs with the dynamical rebinning functionality also cure this minor problem. This upgrade allows users to generate a more accurate RMF; however there is no need to upgrade the corresponding gain files already in the CALDB. In order to allow dynamical rebinning, an additional keyword is required in the existing FEF files: PIBINWID (for PI channel bin width) = 0.01460 [keV/bin]. Regarding PI_FEFS: Acknowledging that there is a problem using the existing PI FEFs, the one channel error described above, we will NOT release corrected PI FEFs. Instead we shall promulgate the use of dynamical rebinning to use PHA FEFs to generate PI RMFs. We shall leave the existing PI_FEFs in the CALDB, but mark them out of the index. They can still be selected by hand, for those who want to repeat earlier analysis. All new analysis should be done by the default dynamical rebinning method in CIAO 2.3. The threads will reflect this change. CAL WEB PAGE: TBD Pipes/Software/Tools affected: CIAO 2.3 mkrmf, mkwarf, acis_fef_lookup Threads affected: "Extract ACIS Spectra for Pointlike Sources and Make RMFs and ARFs" http://cxc.harvard.edu/ciao/threads/psextract/ "Weighting ARFs and RMFs: multiple sources" http://cxc.harvard.edu/ciao/threads/wresp_multiple_sources/index.html "Extracting Extended Source Spectra and Responses" http://cxc.harvard.edu/ciao/threads/acisspec_extract/ E. HRC Amp Scale Factor Correction (AMP_SF_COR) tables Under certain conditions, reconstructed HRC event positions may be distorted by up to a few pixels in either x or y, due to an electronic "ringing" in the crossed-grid charge detector amplifiers. One of the conditions is that the amplifier amplitude scale factor (AMP_SF) be set to the least sensitive value. A fix is in place for the "tap-ringing" but it requires knowledge of each event's AMP_SF value. This is available in telemetry but is often erroneous. It is possible, post-facto, to deduce the correct AMP_SF values based on other data available in the HRC telemetry (see http://hea-www.harvard.edu/~juda/memos/amp_scale/improved_scale_correction.html). The two files contain the parameters required to correct the AMP_SF values for HRC-I and HRC-S. A modified version of hrc_process_events, which can use these files, will be released in CIAO 2.3. CAL WEB PAGE: TBD Pipes/Software/Tools affected: CIAO 2.3/SDP hrc_process_events Threads affected: "HRC AMP_SF Correction and Reducing Tap-Ringing Distortions" http://cxc.harvard.edu/ciao/threads/hrc_ampsf/