A Note on Processing Versions

CIAO 4.4 Science Threads

Overview

Synopsis:

The CIAO Science Threads are designed to work with Chandra data that has been created using recent calibration data. In the past we have referred to this as "reprocessed" data, since early datasets have had to be reprocessed using the new calibration files.

Last Update: 03 Jan 2012 - reviewed for CIAO 4.4 and CALDB 4.4.7: updates to screen output

Checking the pipeline version

Download the sample data: 1843 (ACIS-I, G21.5-0.9)

unix% download_chandra_obsid 1843 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 acisf01843N002_evt2.fits ASCDSVER echo+
7.6.10

For an older version of the same dataset:

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

Read the Reprocessing Data to Create a New Level=2 Event File thread to see if your data needs to be reprocessed.

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 acisf01843N002_evt2.fits CALDBVER echo+ 
3.4.0

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, use the check_ciao_caldb script:

unix% check_ciao_caldb
CALDB environment variable = /soft/ciao-4.4/CALDB
        which is a link to = /data/CALDB/ciao
             CALDB version = 4.4.7
             release date  = 2011-12-15T17:00:00 UTC
CALDB query completed successfully.

CALDB 4.4.7 is installed.

The information is also stored in the caldb_version.fits file:

unix% dmlist "$CALDB/docs/chandra/caldb_version/caldb_version.fits[cols caldb_ver]" data
 
--------------------------------------------------------------------------------
Data for Table Block CALDBVER
--------------------------------------------------------------------------------

ROW    CALDB_VER

     1 4.1.0
     2 4.1.1
     3 4.1.2
     4 4.1.3
     5 4.1.4
     6 4.2.0
...
    20 4.4.6    
    21 4.4.6.1  
    22 4.4.7

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

History