README File for CALDB 4.8.1 Upgrade Only Instructions 23 OCT 2018 DE Graessle, Chandra CALDB Manager Includes brief Intro, Upgrade download and installation instructions, and 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 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. These instructions apply only to those wanting to upgrade their CalDB version 4.7.3 or later version to version 4.8.1 quickly, installing only the updated calibration files and index updates. You must have installed CalDB 4.7.3 or later version previously, or this upgrade installation will not work correctly. Be sure to use the CIAO command "check_ciao_caldb" to verify your CalDB version before proceeding with these instructions. 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 installing the upgrade from CalDB 4.7.3 or later version to 4.8.1. The following are manual installation instructions. You may also download and install CalDB 4.8.1 using the "ciao-install" script at http://cxc.harvard.edu/ciao/download/, or follow the instruction at http://cxc.cfa.harvard.edu/caldb/downloads/index.html. Before you begin, you must have write privileges in your local CalDB area. If you don't have your system administrator do this upgrade! A. As system admin, verify your current CalDB version. With CIAO installed and loaded, enter the command "check_ciao_caldb" If you do not see that the CalDB version is 4.7.3 or later version, you need to use the MAIN CalDB download procedure from Table 1 of the CIAO CalDB downloads page. If the version shown is 4.7.3 or later, proceed with the following: B. Downloading Instructions: Set your working directory to $CALDB, and verify that you are there. Please download the "upgrade" tar ball and either or both of the other tar balls you may need (as indicated below) into the $CALDB area. The following FTP links will allow you to access the files from the Chandra Data Archive. You may also use your web browser to locate the CalDB Download instructions, and proceed from there: http://cxc.harvard.edu/caldb/downloads/index.html CALDB UPGRADE FILE: ftp://cda.harvard.edu/pub/arcftp/caldb/upgrade/caldb_4.8.1_upgrade.tar.gz The ACIS BKGRND files have been updated to include (1) eleven N0002 files in Group G for 2012-01-01 through the present. Added as of the release of CalDB 4.7.6 on 18 Aug 2017. ftp://cda.harvard.edu/pub/arcftp/caldb/acis_bkgrnd_4.7.6.tar.gz Three new HRC-I BKGRND files, effective for calendar years 2015-2017 respectively, have been added to the CalDB as of version 4.7. (14 Dec 2017). As has been the case since their original addition to CalDB, they are packaged separately in the following tar file: ftp://cda.harvard.edu/pub/arcftp/caldb/hrc_bkgrnd_4.7.7.tar.gz TABLE 1: Files, sizes, and md5sum values: FILENAME Ship Size Unpacking space md5sum (bytes) caldb_4.8.1_upgrade.tar.gz 1,523,879,596 4.2 GB 31a23c2f892b10528037054a8417cbb4 acis_bkgrnd_4.7.6.tar.gz 1,387,251,364 2.9 GB 192d4871813c9d5d3e857726195d1261 hrc_bkgrnd_4.7.7.tar.gz 2,323,747,030 3.2 GB 3c9b4e5d6966929793d726b12ae4a4b2 C. Unpacking instructions: We prefer that you use gtar with the appropriate options to unzip and untar the files in a single step, to save disk space and to apply the safest unpacking procedures: gtar xvUfz caldb_4.8.1_upgrade.tar.gz gtar xvfz acis_bkgrnd_4.7.6.tar.gz gtar xvfz hrc_bkgrnd_4.7.7.tar.gz LINUX users: You may omit the "U" uption in the first gtar command. D. Upgrade verification checks See the CalDB downloads web page for steps to verify your upgrade installation, at http://cxc.harvard.edu/caldb/downloads/index.html#dl_config. - Dale Graessle Chandra CalDB Manager