README File for CALDB 4.7.8 Full Download Instructions 01 March 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 4.7.8, see http://cxc.harvard.edu/caldb/downloads/releasenotes.html CalDB 4.7.8 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 4.7.8 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 4.7.8 ------------------------------------------------------------------------------------------ I. INTRODUCTION CalDB 4.7.8 is an upgrade to the Chandra CalDB, which includes the following items: * ACIS T_GAIN Epochs 71+72 updates * HRC-S GAPLOOKUP table version N0004 * Retired 2016 provision T_GAIN files For the CIAO 4.9 / CalDB 4.7.8 release notes see How CalDB 4.7.8 Affects Your Analysis. ------------------------------------------------------------------------------------------ II. SUMMARY OF CHANGES A. ACIS T_GAIN Epochs 71+72 Updates Location: $CALDB/data/chandra/acis/t_gain/ Filenames: acisD2017-05-02t_gainN0005.fits acisD2017-05-02t_gainN0006.fits acisD2017-11-01t_gainN0002.fits acisD2017-11-01t_gain_biN0002.fits The ACIS Calibration team has released new time-dependent gain corrections derived from the External Calibration Source (ECS) during quarterly Epochs 71 (Aug-Oct 2017) and 72 (Nov 2017 - Jan 2018), which have been combined to obtain sufficient counting statistics. With this release, the combined epoch 69+70 CalDB files may be finalized. Users with observations taken between (DATE-OBS=) 2017-05-02T12:00:00 and 2017-11-01T00:00:00 are advised to reprocess with their data with finalized versions of the applicable T_GAIN files. Users with observations taken since 2017-11-01T00:00:00 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 74 (May-July 2018) is completed. For basic information concerning the ACIS Time-dependent Gain Correction, See ACIS Time-dependent Gain why page. For a more detailed explanation, see the Technical Details section below. 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. HRC-S GAPLOOKUP Version N0004 Location: $CALDB/data/chandra/hrc/gaplookup/ Filename: hrcsD1999-07-22gaplookupN0004.fits The CXC HRC-S calibration team has released a correction to the existing GAPLOOKUP table version 3 in the CalDB (released in 27 June 2012 with CalDB 4.5.0), which had a small offset in positions of photons near the aimpoint. This new version N0004 degap file listed above rectifies the issue, by including a shift of +2.5 pixels (approximately 0.018 Ang) to all degap corrections (in CRSV) near the aimpoint position. The new degap solution ameliorates a wavelength shift as seen from tests run on Capella LETGS+HRC-S observations. A full explanation of the new degap correction is given one the HRC Calibration Web page at DEGAP Update for HRC-S2 See the why page for more information on the degap solution in general. For details on this newest GAPLOOKUP table release, see the HRC-S DEGAP Technical Details section below. PIPELINES/TOOLS AFFECTED: Standard HRC Level 1 Data Processing pipeline tool hrc_process_events CIAO script chandra_repro, which uses hrc_process_events to reprocess HRC observation data. THREADS AFFECTED: Reprocessing Data to Create a New Level=2 Event File C. 2016 T_GAIN Provisional Files RETIRED Location: $CALDB/data/chandra/acis/t_gain/ Filenames: acisD2016-02-01t_gain_biN0002.fits acisD2016-02-01t_gainN0002.fits acisD2016-11-01t_gain_biN0002.fits acisD2016-11-01t_gainN0002.fits The above provisional files (flat, non-interpolating) are being deleted from the CalDB distribution with version 4.7.8, and removed from the CalDB ACIS branch index file. These have been in CalDB distribution for more than one year. If users' data file headers show this file as the TGAINFIL value, we suggest they use an upgraded CalDB such as the current release to reprocess their data with the appropriate permanent (finalized) T_GAIN CalDB file for their particular datasets. PIPELINES/TOOLS AFFECTED: None. THREADS AFFECTED: None. ------------------------------------------------------------------------------- III. Instructions for MANUALLY Downloading and Unpacking CALDB 4.7.8 NOTE: The installation of CalDB 4.7.8 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 4.7.8. 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 4.7.8. MAIN CALDB DIRECTORY AND FILES: 1. ftp://cda.harvard.edu/pub/arcftp/caldb/caldb_4.7.8_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_4.7.8_main.tar.gz 3,470,475,043 8.4 GB 6aff11b2cd591b02f0bc7b95532c30ea 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