Which CALDB version is installed on my system?

The CIAO scripts package contains a tool - check_ciao_caldb - that performs a simple check of the Chandra CALDB installation. Running the tool produces screen output like the following:

unix% check_ciao_caldb
CALDB environment variable = /soft/ciao/CALDB
        which is a link to = /data/CALDB/ciao
             CALDB version = 4.9.6
             release date  = 2021-09-21T16:00:00 UTC
CALDB query completed successfully.

This information is also stored in the caldb_version.fits file, which is automatically updated each time the CALDB is upgraded on your system. The final row in the file indicates the current version:

unix% dmlist \
      $CALDB/docs/chandra/caldb_version/caldb_version.fits"[cols caldb_ver]" \
      data,clean | tail -1 
 4.9.6

In this case, CALDB 4.9.6 is being run. The most recent version of the CALDB may be obtained from the CIAO download page.