CalDB 4.9.2.1 Public Release Notes
Public Release Date: 09 July 2020
I. INTRODUCTION
CalDB 4.9.2.1 is an upgrade to the Chandra CalDB, which includes the following items:
CalDB 4.9.2.1 includes CalDB 4.9.2, which was installed in Standard Data Processing (SDP) on 06 July 2020, but not released to the public at that time.
For the CIAO 4.12 / CalDB 4.9.2.1 release notes see How CalDB 4.9.2.1 Affects Your Analysis.
II. SUMMARY OF CHANGES
A. FP_TEMP Boundary Modification for Current ACIS BKGRND Files
| Location: | $CALDB/data/chandra/acis/bkgrnd/ |
| Filenames: | acis5sD2009-09-21bkgrndN0002.fits acis7sD2009-09-21bkgrndN0002.fits acis0iD2012-01-01bkgrnd_ctiN0002.fits acis1iD2012-01-01bkgrnd_ctiN0002.fits acis2iD2012-01-01bkgrnd_ctiN0002.fits acis2sD2012-01-01bkgrnd_ctiN0002.fits acis3iD2012-01-01bkgrnd_ctiN0002.fits acis3sD2012-01-01bkgrnd_ctiN0002.fits acis5sD2012-01-01bkgrnd_ctiN0002.fits acis6iD2012-01-01bkgrnd_ctiN0002.fits acis6sD2012-01-01bkgrnd_ctiN0002.fits acis7sD2012-01-01bkgrnd_ctiN0002.fits acis8sD2012-01-01bkgrnd_ctiN0002.fits acis0D2009-09-21bgstow_ctiN0002.fits acis1D2009-09-21bgstow_ctiN0002.fits acis2D2009-09-21bgstow_ctiN0002.fits acis3D2009-09-21bgstow_ctiN0002.fits acis5D2009-09-21bgstow_ctiN0002.fits acis6D2009-09-21bgstow_ctiN0002.fits acis7D2009-09-21bgstow_ctiN0002.fits |
CalDB 4.9.2.1 is a patch release to CalDB version 4.9.2, which includes modifications to the headers of the above ACIS BKGRND files. The most important change to each file is a modification to the CBD30001 boundary condition, which is for the focal plane temerpature, FP_TEMP. The boundary condition has been changed from 'FP_TEMP(151.16-164.16)K' to 'FP_TEMP(148.15-168.16)K'. This expands the file selection range for FP_TEMP from (-121.99C - -108.99C) to (-125.0C - -104.99C). This change is being made to the above files to allow them to be selected using acis_bkgrnd_lookup when working on OBS_IDs with warmer ACIS FP_TEMP settings.
Given the inevitable warming of the Chandra spacecraft with age, maintaining the ACIS focal plane at -120C throughout the full available orbital period (even with excluding the radiation zone passages) has become increasingly difficult or even impossible. To maintain the science observation schedule, CXC Mission Planning has gotten approval for warmer FP_TEMPs (up to -109C nominally) to be used for science observations, despite the lack of any new high-temperature calibrations in CalDB. Hence, the FP_TEMP boundary conditions for CalDB files need to be expanded.
PIPELINES/TOOLS AFFECTED:
CIAO contributed tool: acis_bkgrnd_lookup
THREADS AFFECTED:
CIAO Data Preparation thread: Analysing the ACIS Background with the "Blank-Sky" Files