README File for CALDB 4.8.2 Full Download Instructions 23 OCT 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 4.8.2, see http://cxc.harvard.edu/caldb/downloads/releasenotes.html CalDB 4.8.2 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 4.8.2 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. CalDB 4.8.2 is being released simultaneously with CIAO 4.11. Condensed Release Notes for CalDB 4.8.2 ------------------------------------------------------------------------------------------ I. Introduction CalDB 4.8.2 is an upgrade to the Chandra CalDB, which includes the following items: * HRC-I GMAP 2018-09-17 Upgrade * HRC-S QEU Version N0010 * HRC-I GMAP 2015 Header Correction * PIMMS Cycle 21 Effective Area FITS files (http://cxc.cfa.harvard.edu/caldb4/prop_plan/pimms/index21.html) For the CIAO 4.11 / CalDB 4.8.2 release notes see How CalDB 4.8.2 Affects Your Analysis, at http://cxc.harvard.edu/ciao/releasenotes/ciao_4.11_release.html#HowCALDB4.8.2AffectsYourAnalysis ------------------------------------------------------------------------------------------ II. SUMMARY OF CHANGES A. HRC-I GMAP 2018-09-17 Upgrade Location: $CALDB/data/chandra/hrc/gmap/ Filename: hrciD2018-09-17sampgainN0001.fits Location: $CALDB/data/chandra/hrc/pibgspec/ Filename: hrciD2018-09-17pibgspecN0001.fits The September 2018 adjustment to the HRC-I time-dependent gain map has been calibrated and has been released. The rate of gain decay continues to increase with time; however the HRC calibration team has determined that an annual GMAP adjustment is adequate to maintain approximately 2-4% global accuracy in the gain. The a new compilation of the same prescribed set of ArLac observations has been used to measure the gain corrections. Details including a plot of the new GMAP and its differences with the previous corrections for 2017 are included in the technical details section of the CalDB 4.8.2 release notes. As with previous HRC-I GMAP updates, these changes will apply only to recent HRC-I observations, specifically those with DATE-OBS later than 2018-09-17T12:00:00 UTC. See the HRC-I gain map why page for more information. PIPELINES/TOOLS AFFECTED: DS and CIAO level 1 (re)processing tool hrc_process_events Also: CIAO reprocessing script chandra_repro THREADS AFFECTED: Reprocessing Data to Create a New L2 Events File Along with the new 2017 HRC-I GMAP, the incumbent PIBGSPEC for September 2018 is also being released. The PI background spectrum changes with the GMAP, because background events reprocessed using the new GMAP, using the point-source observations as are used to generate the new GMAP. This results in a shift in the background spectrum in channel space relative to the previous spectrum file. Details of how the derivation is done, and a plot of the new spectrum in comparison with previous PIBGSPEC files are given in the technical details section of the CalDB 4.8.2 release notes on the CalDB web page. PIPELINES/TOOLS AFFECTED: CIAO tool hrc_bkgrnd_lookup THREADS AFFECTED: HRC-I Background Spectra Files B. HRC-S QEU Version N0010 Location: $CALDB/data/chandra/hrc/qeu/ Filename: hrcsD1999-07-22qeuN0010.fits hrcsD2000-01-01qeuN0010.fits hrcsD2001-01-01qeuN0010.fits hrcsD2002-01-01qeuN0010.fits hrcsD2003-01-01qeuN0010.fits hrcsD2004-01-01qeuN0010.fits hrcsD2005-01-01qeuN0010.fits hrcsD2006-01-01qeuN0010.fits hrcsD2007-01-01qeuN0010.fits hrcsD2008-01-01qeuN0010.fits hrcsD2009-01-01qeuN0010.fits hrcsD2009-08-08qeuN0010.fits hrcsD2010-09-14qeuN0010.fits hrcsD2012-03-29qeuN0010.fits hrcsD2012-10-05qeuN0010.fits hrcsD2013-09-21qeuN0010.fits hrcsD2015-02-17qeuN0010.fits hrcsD2016-02-22qeuN0010.fits hrcsD2016-07-28qeuN0010.fits hrcsD2017-01-23qeuN0010.fits hrcsD2017-06-05qeuN0010.fits hrcsD2017-09-26qeuN0010.fits hrcsD2018-01-19qeuN0010.fits hrcsD2018-05-27qeuN0010.fits As the LETGS calibration team has monitored the accelerated rate of decay in the HRC-S quantum efficiency as a function of wavelength, they have elected to replace the current set of time dependent QE Uniformity (QEU) files (version N0009) with another new set of files, version N0010. One additional file has been added to the set, with new effective date of 2018-05-20T00:00:00, so that the set includes 24 files now. See the technical details section of the release notes for illustrations and details of the derivation of these new QE Uniformity corrections. In general, this latest set accounts for an additional 2.5% of QE loss over the 0.060 - 0.652 keV range; above that range, the change is minimal. See also the why page for more general information on the HRC-S QE/QEU corrections in the CalDB. CIAO SCRIPTS/TOOLS AFFECTED: See the script fluximage, which uses mkinstmap THREADS AFFECTED: For exposure-corrected imaging analysis with HRC-S, see the thread: HRC-S Exposure Map and Exposure-corrected Image For grating spectroscopy with the LETG/HRC-S, see the thread: LETG/HRC-S Grating ARFs C. HRC-I GMAP 2015 Header Correction Location: $CALDB/data/chandra/hrc/gmap/ Filename: hrciD2015-09-27sampgainN0001.fits The HRC-I GMAP (sampgain) file named above has an incorrect CVSD0001 keyword value, which causes it to become effective earlier than it should be, but because of the justapostion of previously released HRC-I GMAP files in CalDB, results in the file only being selected when it should be after all. Hence, the change being made here has zero effect on GMAP file selection for any HRC-I OBS_ID; however we are correcting it just in case a future change to an earlier GMAP file will not result in new selection issues that are not currently occurring. The calibration validity start date of the above file has been originally set at (UTC) 2012-09-27T12:00:00 instead of the correct value of 2015-09-27T12:00:00. With the CalDB 4.8.2 release, this value will be set to the correct value in the named file. The CalDB Manager has verified the named file has been being selected and applied in reprocessing with either the CIAO tool chandra_repro, as well as in the DS software that is used for scheduled archival reprocessing, despite the header error. More details are given in the technical section of the release notes, but in general users may ignore this information and proceed with any HRC-I observation reprocessing without concern for this change. ------------------------------------------------------------------------------- III. Instructions for MANUALLY Downloading and Unpacking CALDB 4.8.2 NOTE: The installation of CalDB 4.8.2 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 4.8.2. 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 4.8.2. MAIN CALDB DIRECTORY AND FILES: 1. ftp://cda.harvard.edu/pub/arcftp/caldb/caldb_4.8.2_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_4.8.2_main.tar.gz 3,558,462,798 7.8 GB c6e756c0fbd135a80869f3107b478d8e 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