README File for CALDB 4.8.4.1 Full Download Instructions 11 SEP 2019 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 4.8.4.1, see http://cxc.harvard.edu/caldb/downloads/releasenotes.html Condensed Release Notes for CalDB 4.8.4.1 ------------------------------------------------------------------------------------------ I. Introduction CalDB 4.8.4.1 is an upgrade to the Chandra CalDB, which includes the following items: * ACIS T_GAIN Epochs 75+76 and 77+78 emergency corrections For the CIAO 4.11 / CalDB 4.8.4.1 release notes see How CalDB 4.8.4.1 Affects Your Analysis, at http://cxc.harvard.edu/ciao/releasenotes/ciao_4.11_release.html#HowCALDB4.8.4.1AffectsYourAnalysis ------------------------------------------------------------------------------------------ II. SUMMARY OF CHANGES A. Emergency Corrections for ACIS T_GAIN Epochs 75+76 and 77+78 Location: $CALDB/data/chandra/acis/t_gain/ Filenames: acisD2018-05-02t_gainN0005_revA.fits acisD2018-05-02t_gainN0006_revA.fits acisD2018-11-01t_gainN0005_revA.fits acisD2018-11-01t_gainN0006_revA.fits acisD2019-05-02t_gain_biN0002_revA.fits acisD2019-05-02t_gainN0002_revA.fits The ACIS calibration team has reported an undetected error in the calibration products for the combined T_GAIN epochs 75+76, and 77+78, covering the bi-epochal periods of Aug 2018 - Jan 2019, and Feb - July 2019. The error occurred due to a single line of code in the recently modified file generator of the calibration interface product files used by the CalDB Manager to generate the ACIS T_GAIN files employed in the CalDB. Only ACIS chips 0, 1, 2, 3 and 6 have been affected. This error produced alternating columns of zero t_gain correction values in the DELTAPHA column of the CIPs, which were then transfered to the CalDB T_GAIN files in their DELTPHA2 and DELTPHA1 columns. The errant files, affected columns, Standard Data Processing (SDP) installation dates, and corresponding corrected files are listed in Table 1 below. TABLE 1: List of Affected T_GAIN files by name, with details, and their corresponding corrected filenames in CalDB 4.8.4.1. Errant T_GAIN File FITS Columns Affected Errant File Errant File Corrected T_GAIN File by the Error CalDB Version SDP Installation Date acisD2018-05-02t_gainN0005.fits DELTPHA2 4.8.3 2019-05-24T01:06:00 acisD2018-05-02t_gainN0005_revA.fits acisD2018-05-02t_gainN0006.fits DELTPHA2 4.8.3 2019-05-24T01:06:00 acisD2018-05-02t_gainN0006_revA.fits acisD2018-11-01t_gainN0002.fits DELTPHA2 4.8.3 2019-05-24T01:06:00 acisD2018-11-01t_gainN0005_revA.fits acisD2018-11-01t_gain_biN0002.fits DELTPHA2 4.8.3 2019-05-24T01:06:00 acisD2018-11-01t_gainN0006_revA.fits acisD2018-11-01t_gainN0005.fits DELTPHA1, DELTPHA2 4.8.4 2019-08-28T19:11:12 acisD2018-11-01t_gainN0005_revA.fits acisD2018-11-01t_gainN0006.fits DELTPHA1, DELTPHA2 4.8.4 2019-08-28T19:11:12 acisD2018-11-01t_gainN0006_revA.fits acisD2019-05-02t_gain_biN0002.fits DELTPHA1, DELTPHA2 4.8.4 2019-08-28T19:11:12 acisD2019-05-02t_gain_biN0002_revA.fits acisD2019-05-02t_gainN0002.fits DELTPHA1, DELTPHA2 4.8.4 2019-08-28T19:11:12 acisD2019-05-02t_gainN0002_revA.fits These errant CalDB files were then released to the public, the first four files on 23 May 2019 with CalDB 4.8.3, and the latter four files on 09 Sep 2019 with CalDB 4.8.4. Hence, any reprocessing by users (e.g. with chandra_repro) with either CalDB would have affected any ACIS observations employing ACIS-0,1,2,3,4, or 6 with a DATE-OBS of 2018-05-02T12:00:00 or any later date. The error was detected by 05 September, and corrected in processing on 2019-09-06T17:31:43 (UTC). Any data sets processed in SDP after that date are unaffected by the error. (See the DATE keyword in observation data file headers.) Details describing the exact nature of the error are given in the technical details section below. DS Operations have determined that 302 OBS_IDs have been affected in processing by the errors in T_GAIN, including 127 ACIS-I observations, and 175 ACIS-S observations that used ACIS-6 (S2). Among these are seven ACIS/Grating observations which are on the public archive. All of these OBS_IDs will be reprocessed for the archive using the correctioned T_GAIN files released in CalDB 4.8.4.1. Users and PIs will be notified in a timely fashion of these errors and their appropriate reparations to the data. PIPELINES/TOOLS AFFECTED: ACIS Level 1 pipeline tool acis_process_events. CIAO script chandra_repro uses acis_process_events to reprocess ACIS observation data. ------------------------------------------------------------------------------- III. Instructions for MANUALLY Downloading and Unpacking CALDB 4.8.4.1 NOTE: The installation of CalDB 4.8.4.1 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 4.8.4.1. You will need at least 20 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 6.1 GB to the space you need. See the following ftp links to acquire the CALDB download tar files for version 4.8.4.1. MAIN CALDB DIRECTORY AND FILES: 1. ftp://cda.harvard.edu/pub/arcftp/caldb/caldb_4.8.4.1_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_4.8.4.1_main.tar.gz 3,648,118,781 8.1 GB 39b66f5d9f3bbc2b7fc5ecc56b721c7f 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