& README File for CALDB 4.8.0 Full Download Instructions 06 Sept 2018 DE Graessle, Chandra CALDB Manager Includes brief Intro, Download instructions, Unpacking instructions, Pointers for further assistance. To learn more about the Chandra CALDB, and to find this information on the WEB, you are referred to http://cxc.harvard.edu/caldb/index.html. For Release Notes to the Chandra CALDB4, and specifically CalDB 4.8.0, see http://cxc.harvard.edu/caldb/downloads/releasenotes.html CalDB 4.8.0 requires CIAO 4.5 (or later version) because of an upgrade to the caldb4 software that was included since the release of CIAO 4.5 in December of 2012. The caldb4 upgrade in question provides for the proper selection of time-displaced CalDB files with overlapping validity date ranges, which does not exist in earlier CIAO versions. CalDB 4.8.0 is optimized for CIAO 4.8 (or later version) which includes an upgrade to the acis_process_events tool (a-p-e) for handling CC-mode observations, specifically to perform the CTI-correction properly for them. As a result, the EDSER SUBPIX algorithm is now applied in a-p-e to CC-modes, where it had not been before. Condensed Release Notes for CalDB 4.8.0 ------------------------------------------------------------------------------------------ I. INTRODUCTION CalDB 4.8.0 is an upgrade to the Chandra CalDB, which includes the following items: * ACIS T_GAIN Epoch 73+74 updates (Feb 01 - Jul 31 2018) * ACIS early N0005 T_GAIN header corrections (47 files) For the CIAO 4.10 / CalDB 4.8.0 release notes see How CalDB 4.8.0 Affects Your Analysis at http://cxc.harvard.edu/ciao/releasenotes/ciao_4.10_release.html#HowCALDB4.8.0AffectsYourAnalysis ------------------------------------------------------------------------------------------ II. SUMMARY OF CHANGES A. ACIS T_GAIN Epochs 73+74 (Feb-Jul 2018) Location: $CALDB/data/chandra/acis/t_gain/ Filenames: acisD2017-11-01t_gainN0005.fits acisD2017-11-01t_gainN0006.fits acisD2018-05-02t_gainN0002.fits acisD2018-05-02t_gain_biN0002.fits The ACIS Calibration team has released the semiannual time-dependent gain (T_GAIN) updates from analysis of ECS data for the period Feb 01 - Jul 31 2018 (epochs 73+74), and hence the above files have been generated as a result, for immediate release. The secular time variations in the corrections calculated from these new data are similar in magnitude and direction to previous upgrades, wherein maximal changes are a few percent or less of the deltaE/E value. In particular the variations at the ACIS-I aimpoint are significant, whereas those at the ACIS-S aimpoint are very small for this period and the previous epochal period (epochs 71+72, Aug 01 2017 - Jan 31 2018) which is now finalized. NOTE: Users with observations taken between (DATE-OBS=) 2017-11-01T12:00:00 and 2018-05-02T12:00:00 are advised to reprocess with their data with finalized versions of the applicable T_GAIN files. Users with observations taken since 2018-05-02T12:00:00 will have access to an updated provisional T_GAIN file (one of the version N0002 filenames above); They will not however have a finalized file until after Epoch 76 (Nov 01 2018 - Jan 31 2019) is completed. For a presentation of the specific values, see the Technical Details Section for these data in the CalDB 4.8.0 release notes. For more information on the ACIS time-dependent gain in general, see the ACIS T_GAIN why page. PIPELINES/TOOLS AFFECTED: ACIS Level 1 pipeline tool acis_process_events. CIAO script chandra_repro uses acis_process_events to reprocess ACIS observation data. THREADS AFFECTED: Reprocessing Data to Create a New Level=2 Event File B. ACIS T_GAIN N0005 Early Epochs Header Modifications Location: $CALDB/data/chandra/acis/t_gain/ Filenames: acisD2000-01-29t_gainN0005.fits acisD2000-05-01t_gainN0005.fits acisD2000-08-01t_gainN0005.fits acisD2000-11-01t_gainN0005.fits acisD2001-02-01t_gainN0005.fits acisD2001-05-01t_gainN0005.fits acisD2001-08-01t_gainN0005.fits acisD2001-11-01t_gainN0005.fits acisD2002-02-01t_gainN0005.fits acisD2002-05-01t_gainN0005.fits acisD2002-08-01t_gainN0005.fits acisD2002-11-01t_gainN0005.fits acisD2003-02-01t_gainN0005.fits acisD2003-05-01t_gainN0005.fits acisD2003-08-01t_gainN0005.fits acisD2003-10-19t_gainN0005.fits acisD2003-11-18t_gainN0005.fits acisD2004-01-01t_gainN0005.fits acisD2004-02-01t_gainN0005.fits acisD2004-05-01t_gainN0005.fits acisD2004-08-01t_gainN0005.fits acisD2004-11-01t_gainN0005.fits acisD2005-02-01t_gainN0005_revA.fits acisD2005-05-01t_gainN0005_revA.fits acisD2005-08-02t_gainN0005.fits acisD2005-11-01t_gainN0005.fits acisD2006-02-01t_gainN0005.fits acisD2006-05-01t_gainN0005.fits acisD2006-08-01t_gainN0005.fits acisD2006-11-01t_gainN0005.fits acisD2007-02-01t_gainN0005.fits acisD2007-05-01t_gainN0005.fits acisD2007-08-01t_gainN0005.fits acisD2007-11-01t_gainN0005.fits acisD2008-02-01t_gainN0005.fits acisD2008-05-01t_gainN0005.fits acisD2008-08-01t_gainN0005.fits acisD2008-11-01t_gainN0005.fits acisD2009-02-01t_gainN0005.fits acisD2009-05-01t_gainN0005.fits acisD2009-08-01t_gainN0005.fits acisD2010-02-01t_gainN0005.fits acisD2010-05-01t_gainN0005_revA.fits acisD2010-08-01t_gainN0005.fits acisD2010-11-01t_gainN0005.fits acisD2011-02-01t_gainN0005.fits acisD2011-05-01t_gainN0005.fits The ACIS Calibration Team has begun analysis peculiar to their own purposes of External Calibration Source (ECS) data taken with warmer than usual FP_TEMP values; part of their procedure is to reprocess these ERs removing the CTI correction, but having the "apply_tgain" parameter set to "yes", so that a T_GAIN file should still be selected and applied. Ordinarily these ERs are not in GRADED data mode, so that the N0006 (full CTI correction) T_GAIN files are selected for these. With the CTI correcction OFF, CTI_APP = NNNNNNNNNN, and the corresponding N0005 file would be selected. For some of the warmer FP_TEMPs, however, it has been found that the default FP_TEMP boundary condition range was set to (148.2-158.2)K, which for some 24 ERs, a-p-e returns "NO FILES FOUND" for the T_GAIN, and turns off the apply_tgain parameter, leaving the data uncorrected. There were however four additional cases where ERs were taken with normal FP_TEMPs, but still no T_GAIN could be found. It was determined that these cases were at periods crossing the epochal boundaries of the T_GAIN files. The effective date ranges for these cases had been fixed for the usual N0006 (CTI-corrected) T_GAINs in CalDB 4.5.0 (June 2012). See also the CalDB caveats page 38 ACIS OBS_IDs with "Problem Reading TGAINFILE However the corresponding N0005 files had not been corrected for this situation. Hence, turning off the CTI correction causes the T_GAIN CalDB search to fail for them. The solution is to correct the Calibration Validity End Dates CVED* (and Times) CVET* in those N0005 file headers to be the same as those for the corresponding N0006 files. It has been decided for the sake of consistency that all of the -120C N0005 T_GAIN files from 29 Jan 2000 through 2011 May 01 should have their FP_TEMP ranges reset to (148.2 - 188.2)K, the standard setting used for all current T_GAINs for the OBS_MODE=SECONDARY case, which is the setting for the ACIS ECS ERs. Such a change will not affect the reprocessing of ordinary observations. It will, however, allow the procedure used by the ACIS Calibration team to be performed on any observation (ER or OR), with a non-CTI T_GAIN always being available, regardless of the FP_TEMP, the DATE-OBS, or the DATE-END of the observation. ------------------------------------------------------------------------------- III. Instructions for MANUALLY Downloading and Unpacking CALDB 4.8.0 NOTE: The installation of CalDB 4.8.0 may be done automatically by using the new ciao-install routine, as a matter of course, when installing or upgrading CIAO. See the instruction at "Downloading CIAO ", http://cxc.harvard.edu/ciao/download/ Instructions for Downloading (Manually): Download all files into the same directory, where you intend to install your Chandra CALDB 4.8.0. You will need at least 15 GBytes free to download and unpack the basic structure. The ACIS & HRC background files are now packaged separately, so you don't have to install it to get the basic package. The background files add another 5.2 GB to the space you need. See the following ftp links to acquire the CALDB download tar files for version 4.8.0. MAIN CALDB DIRECTORY AND FILES: 1. ftp://cda.harvard.edu/pub/arcftp/caldb/caldb_4.8.0_main.tar.gz The ACIS and HRC-I background files (blank-field files) are now packaged separately, so if you want to use them you will need files 2 and 3. You need these files if you are going to run reproject_events to generate background files for your ACIS or HRC-I observations. 2. The ACIS BKGRND files tar ball was most recently upgraded with CalDB 4.7.6, 18 Aug 2017 to include version N0002 of the Group G event lists (effective 2012-01-01 through the present.) ftp://cda.harvard.edu/pub/arcftp/caldb/acis_bkgrnd_4.7.6.tar.gz 3. The HRC-I BKGRND files tar ball has been newly upgraded in CalDB 4.7.7 (14 Dec 2017), to include the new background files effective for 2015-2017 calendar years, respectively. ftp://cda.harvard.edu/pub/arcftp/caldb/hrc_bkgrnd_4.7.7.tar.gz TABLE 1: Files and sizes: FILE FILENAME Ship Size(byte) Unpacking space md5sum 1 caldb_4.8.0_main.tar.gz 3,527,314,291 7.6 GB 79778c7e9d3d45a03b428f96ad3764e2 2 acis_bkgrnd_4.7.6.tar.gz 1,387,251,364 2.9 GB 192d4871813c9d5d3e857726195d1261 3 hrc_bkgrnd_4.7.7.tar.gz 2,323,747,030 3.2 GB 3c9b4e5d6966929793d726b12ae4a4b2 Instructions for unpacking: 1. Locate a place for your CALDB. Designate an empty directory to be assigned to the value of $CALDB. Unpack file 1 above from that location. 2. It is not necessary to edit the ./software/tools/caldbinit.* files. When you install or load CIAO, the location of the CalDB gets set up to the appropriate directory. 3. Unpack the ACIS "background" files (File 2 in the table above) if you expect to use them. The files take up a large amount of space. 4. Unpack the HRC "background" files (File 3 in the table above) if you expect to use them. The files take up a large amount of space. 5. Delete the tar files. The latest versions will be maintained online at CXC at all times. -- Chandra CALDB Manager