Chandra X-Ray Observatory
Skip to the navigation links
Last modified: November 2015

AHELP for CIAO 4.9


Context: tools


A tool to test the installation of the CIAO Calibration Database (CALDB)


check_ciao_caldb --latest


The check_ciao_caldb tool allows users to easily check that the CIAO Calibration Database (CALDB) is installed correctly. It is intended to be used after installing or upgrading CIAO, or to help diagnose problems seen with other CIAO toos.

The tool only tests the basic installation, and so provides a quick and easy test. It does not perform the same verification steps as either the calvalid tool from CIAO (see "ahelp calvalid") or the the chkcif tool from the FTOOLS package (as described on the Download the CIAO CALDB page), which should be used for a more thorough evaluation.

Tool behavior

As shown in the example below, the tool will print out some basic information on the CALDB installation, and then exit with a status value of 0 when the installation is correct. If there is a problem then an error message will be displayed and the exit status will be set to a non-zero value.

The --latest flag

Calling the script with the --latest flag will check whether there are any newer versions of the CALDB available. This step requires internet access. If a newer version is available then see the CALDB downloads page or the ciao_install thread.


The check_ciao_caldb tool is part of the CIAO contributed scripts package which should have been included as part of the CIAO installation.

Example 1

unix% check_ciao_caldb

The tool accepts no arguments. If the Chandra CALDB is set up correctly then you should see something like the following:

CALDB environment variable = /soft/ciao-4.2/CALDB
             CALDB version = 4.2.2
             release date  = 2010-04-19T19:00:00 UTC
CALDB query completed successfully.

The actual output will vary depending on where, and what version, of the CALDB is installed.

Example 2

unix% check_ciao_caldb --latest

As the --latest flag has been given, the tool also checks whether there is a newer version of the CALDB available. The extra screen output will either be:

The CALDB installation is up to date.

when there is no newer version available, or

ERROR: The latest available CALDB version is <latest version>

for when there is.

What is checked?

The script is intended to provide a simple check of the CALDB installation, to pick up some of the common problems seen in HelpDesk tickets, rather than a complete check of the integrity of the Chandra CALDB. It therefore just checks that:

  • The CALDB envrionment variable exists, and points to a directory;
  • the directory contains a Chandra version file in the correct location;
  • and that a query for the DET_GAIN product (a basic element required for re-processing ACIS event lists with acis_process_events) returns a file and that this file can be read in.

The script does not check for any ancillary CALDB products that may have been installed, such as the ACIS background files or the PSF libraries.

Version check

The --latest flag causes the script to look at the CALDB release notes page to look for the latest version released for CIAO, and this value is compared against the version of the local CALDB installation.

Changes in the scripts 4.8.1 (December 2015) release

The code has been updated to avoid warning messages from NumPy version 1.9. There is no difference to how the script behaves.

About Contributed Software

This tool is not an official part of the CIAO release but is made available as "contributed" software via the CIAO scripts page. Please see the installation instructions page for help on installing the package.


See the bugs page on the CIAO website for an up-to-date listing of known bugs.

Refer to the CIAO bug pages for an up-to-date listing of known issues.

See Also

calindex, calmerge, calquiz, calvalid, check_ciao_version

Last modified: November 2015
Smithsonian Institute Smithsonian Institute

The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email: Smithsonian Institution, Copyright © 1998-2017. All rights reserved.