README File for CALDB 4.9.3 Full Download Instructions 14 October 2020 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 4.9.3, see http://cxc.harvard.edu/caldb/downloads/releasenotes.html This README refers to the FULL CalDB 4.9.3 installation, which should only be necessary here forward with a new installation of CIAO 4.12. CalDB 4.9.3 is an upgrade to CalDB 4.9.0. For those who have already downloaded and installed CIAO 4.12 with CalDB 4.9.0, only the upgrade file is actually necessary to upgrade your CalDB. CalDB 4.9.3 is compatible with CIAO 4.12 and later versions ONLY! Please do not attempt to upgrade your CalDB for CIAO 4.11 or older versions with CalDB version 4.9.3. None of the ACIS upgrades in CalDB 4.9.0 will be applied with the older software because of required software changes to do so. Furthermore, the HRC-S chip edge offset values will not be applied in CIAO 4.11 with CalDB 4.9.3, and users will not be notified by the software if this occurs. Condensed Release Notes for CalDB 4.9.3 ------------------------------------------------------------------------------------------ I. Introduction CalDB 4.9.3 is an upgrade to the Chandra CalDB, which includes the following items: * ACIS T_GAIN Epochs 77-82 * HRC-I GTI_LIM for HV Ramp-Up Procedure For the CIAO 4.12 / CalDB 4.9.3 release notes see How CalDB 4.9.3 Affects Your Analysis, at https://cxc.cfa.harvard.edu/ciao/releasenotes/ciao_4.12.1_release.html"#HowCALDB4.9.3AffectsYourAnalysis" ------------------------------------------------------------------------------------------ II. SUMMARY OF CHANGES A. ACIS T_GAIN Epochs 77-82 Location: $CALDB/data/chandra/acis/t_gain/ Filenames: acisD2019-05-02t_gainN0008B_revA.fits acisD2019-05-02t_gainN0008_revA.fits acisD2019-11-01t_gainN0008B.fits acisD2019-11-01t_gainN0008.fits acisD2020-05-02t_gain_biN0002.fits acisD2020-05-02t_gainN0002.fits The ACIS Calibration team has released new time-dependent gain correction data from the most recently complweted bi-epochal period, namely Epochs 81+82 (Feb-Jul 2020). With this release it is now possible to finalize the T_GAIN for the previous bi-epochal period (Epochs 79+80, Aug 2019 through Jan 2020). These updates are included in the files above with effecive dates 2020-05-02 (provisional) and 2019-11-01 (finalized) respectively. As with recent previous epochs, the T_GAIN calibration continues to be challenged by the ever poorer statistics available from the ACIS External Calibration Source (ECS), which continues to decline in intensity as expected over time. However, a new data reduction method involving trend evaluation which considers a full year of ECS data to influence ("nudge") the semi-annual results, has produced considerable improvement in the latest data sets. The new technique was applied to the Epochs 77+78 period (Feb-Jul 2019) in addition to the bi-epochal periods above. Hence a "_revA" version of the previously-released 2019-05-02 T_GAIN files, and are listed above as well. This release affects all ACIS observations taken since 2019-05-02T12:00:00, and users of any OBS_IDs with DATE-OBS later than that date are encouraged to reprocess their datasets. The degree of the corrections is similar to those of previous T_GAIN releases, and those analyzing narrow line-source data are the most likely to be affected signficantly. See the technical details section below for further information. See the why page for a more basic explanation of the time-dependent gain correction. 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-I GTI_LIM for HV Ramp-Up Procedure Location: $CALDB/data/chandra/hrc/gti_lim/ Filename: hrciD2020-09-28gti_limN0001.fits The recent HRC power supply anomaly aboard Chandra has required that the detectors be powered down so that the "B-side" electronics could be implemented. Power to HRC was then reestablished successfully, and most recently the HRC-I high voltage settings have been brought back up again. The procedure was completed over 2020-09-28 through 2020-09-29, with a manual procedure to "ramp up" the HV. The HRC instrument team requested that a modified GTI limits file be used for the data taken during the ramp-up procedure so that events could be delivered to L2 despite the GTI limits being applied. The modification was to removed the line from the HRC-I GTI_LIM file which includes the HV limits. A file with that prescription is listed above, and is to be effective in CalDB for only the period of 2020-09-28T00:00:00 until 2020-09-30T00:00:00. PIPELINES/TOOLS AFFECTED: In standard data processing (SDP) only, the tool mtl_build_gti, first run only for the "standard" GTI limits configuration, which is the only case in which the parameter lkupfile is actually set to "CALDB", so that the CalDB GTI_LIM file for HRC-I is actually delivered. THREADS AFFECTED: No CIAO threads are affected by this change. ------------------------------------------------------------------------------- III. Instructions for MANUALLY Downloading and Unpacking CALDB 4.9.3 NOTE: The installation of CalDB 4.9.3 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 4.9.3. 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 4.9.3. MAIN CALDB DIRECTORY AND FILES: 1. ftp://cda.harvard.edu/pub/arcftp/caldb/caldb_4.9.3_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.) Some header updates were included in CalDB 4.9.2.1 in July 2020. ftp://cda.harvard.edu/pub/arcftp/caldb/acis_bkgrnd_4.9.2.1.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_4.9.3_main.tar.gz 1,746,229,095 5.1 GB 529837d1b16cf4b307abcd60b0422d7e 2 acis_bkgrnd_4.9.2.1.tar.gz 1,387,254,665 2.9 GB ea9c6dec632d6efae242b426513cc3f4 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