README File for CALDB 4.8.1 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 4.8.1, see http://cxc.harvard.edu/caldb/downloads/releasenotes.html CalDB 4.8.1 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 4.8.1 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 4.8.1 ------------------------------------------------------------------------------------------ I. INTRODUCTION CalDB 4.8.1 is an upgrade to the Chandra CalDB, which includes the following items: * ACIS CONTAM Version N0012 (with updates to the ACIS-S model only) For the CIAO 4.10 / CalDB 4.8.1 release notes see How CalDB 4.8.1 Affects Your Analysis at http://cxc.harvard.edu/ciao/releasenotes/ciao_4.10_release.html#HowCALDB4.8.1AffectsYourAnalysis ------------------------------------------------------------------------------------------ II. SUMMARY OF CHANGES A. ACIS CONTAM File Version N0012 Location: $CALDB/data/chandra/acis/contam/ Filename: acisD1999-08-13contamN0012.fits On-going verifications of the contamination correction with time have revealed recently that the model has been over-estimating the contaminant since early 2018, and that an adjustment is needed to both the ACIS-I and ACIS-S time-dependent models. The corrected model for ACIS-I (CONTAM version N0011) was released in CalDB 4.7.9. As promised with that release, the ACIS Calibration Team has developed a modified ACIS-S contamination model as test version, copied to CalDB CONTAM version N0012. That new model includes a more complicated time-dependence in the layers corresponding to the different identified chemical elements in the contaminant, namely C, O, and F. In the previous releases, the layers corresponded to specific elements known to be present in the contaminant: C, O, and F. However, the layers actually represent the different spectral absorption models of the components of the contaminant. The details of the absorption model depend on the chemical bonding of the molecules that comprise the material but because it is now clear that there are (at least) two different components with different C:O:F ratios, the molecules are not likely to have the same bonding structure. The near edge structure of the absorption model is particularly sensitive to the types of bonds and the transmission grating spectra now show that the F-K and O-K near edge structures are time-dependent. To avoid excess absorption near the edge, one layer each of F and O were added that have no near edge structure and these simple, Henke-like edges have been assigned different time dependencies than the versions of the F and O opacities that have clear structure near the edges. Hence the new ACIS-S contamination model includes two additional rows of data values in the tau0 and tau1 arrays, which include the opacities for F and O with no near-edge structure. See the technical details section below for further information on the upgrade to the ACIS-S model, as well as the updated time base. See the why page for more general information on the ACIS OBF contamination effect. CIAO SCRIPTS/TOOLS AFFECTED: See the script fluximage, which uses mkinstmap http://cxc-dmz-prev.cfa.harvard.edu/ciao/ahelp/fluximage.html See the script specextract, which uses mkwarf http://cxc-dmz-prev.cfa.harvard.edu/ciao/ahelp/specextract.html See the script fullgarf, which uses mkgarf http://cxc-dmz-prev.cfa.harvard.edu/ciao/ahelp/fullgarf.html THREADS AFFECTED: For exposure-corrected imaging analysis with ACIS, see the threads: Single Chip ACIS Exposure Map and Exposure-corrected Image http://cxc-dmz-prev.cfa.harvard.edu/ciao/threads/expmap_acis_single/ Multiple Chip ACIS Exposure Map and Exposure-corrected Image http://cxc-dmz-prev.cfa.harvard.edu/ciao/threads/expmap_acis_multi/ For imaging spectroscopy with ACIS, see the threads: Extract Spectrum and Response Files for a Pointlike Source http://cxc-dmz-prev.cfa.harvard.edu/ciao/threads/pointlike/ Extract Spectrum and Response Files for an Extended Source http://cxc-dmz-prev.cfa.harvard.edu/ciao/threads/extended/ Extract Spectrum and Response Files for Multiple Sources http://cxc-dmz-prev.cfa.harvard.edu/ciao/threads/wresp_multiple_sources/ For grating spectroscopy with ACIS, see the threads: HETG/ACIS-S Grating ARFs: http://cxc-dmz-prev.cfa.harvard.edu/ciao/threads/mkgarf_hetgacis/ LETG/ACIS-S Grating ARFs: http://cxc-dmz-prev.cfa.harvard.edu/ciao/threads/mkgarf_letgacis/ ------------------------------------------------------------------------------- III. Instructions for MANUALLY Downloading and Unpacking CALDB 4.8.1 NOTE: The installation of CalDB 4.8.1 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 4.8.1. 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 4.8.1. MAIN CALDB DIRECTORY AND FILES: 1. ftp://cda.harvard.edu/pub/arcftp/caldb/caldb_4.8.1_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_4.8.1_main.tar.gz 3,555,021,326 7.8 GB b91c02106c7781b56235b6c2b09bd8cc 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