A Note on Processing Versions

Checking the pipeline version

Sample ObsIDs used: 1843 (ACIS-I, G21.5-0.9); 578 (ACIS-S, 3C 295)

File types needed: evt2

The version naming convention changed after version R4CU5UPD14 to the "DS" system, starting with DS 6.0.0. Any data with a processing version of DS 6.0.0 or higher is more recent than R4CU5UPD14.

The processing version information is stored in the ASCDSVER keyword:

unix% dmkeypar acisf01843N001_evt2.fits ASCDSVER echo+
R4CU5UPD8.2

For a more recent dataset:

unix% dmkeypar acisf00578N002_evt2.fits ASCDSVER echo+
6.1.0

Checking the CALDB version

It is also useful to check the version of the CALDB used in processing, since the threads reference the CALDBVER header keyword when discussing processing changes:

unix% dmkeypar acisf01843N001_evt2.fits CALDBVER echo+ 
1.4

unix% dmkeypar acisf00578N002_evt2.fits CALDBVER echo+
2.6

The CALDBVER header keyword is not updated by the CIAO tools. The value always reflects the version of the CALDB applied in standard data processing (SDP).

To find out which version of the CALDB you are running on your local system, look in the caldb_version.fits file:

unix% dmlist "$CALDB/docs/chandra/caldb_version/caldb_version.fits[cols caldb_ver,ciao_ver]" data
 
--------------------------------------------------------------------------------
Data for Table Block CALDBVER
--------------------------------------------------------------------------------
 
ROW    CALDB_VER CIAO_VER   
 
     1 1.000   CIAO1.1    
     2 1.1     CIAO1.1.1  
.
. (output omitted)
.
    51 3.2.3   CIAO3.3.0.1  
    52 3.2.4   CIAO3.3.0.1  
    53 3.3.0   CIAO3.4    

This file is automatically updated each time the CALDB is upgraded on your system, so the final row always indicates the current version.