Chandra X-Ray Observatory
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Last modified: 14 December 2015

URL: http://cxc.harvard.edu/caldb/index.html

Welcome to the
Chandra Calibration Database Website


The Chandra X-Ray Center has introduced version 4.7.0 of the Chandra Calibration Database (CALDB) on 15 DEC 2015.

The CalDB 4.7.0 upgrade is a patch upgrade to CalDB 4.6.5 and later versions, but is also being simultaneously released with CIAO 4.8. While CalDB 4.7.0 will work properly in CIAO 4.7, the CC-mode calibration updates are only optimal with the new CIAO 4.8 modifications for CC-mode reprocessing.

See the CIAO Downloads page for instructions for an automated installation of CIAO 4.8 and CalDB 4.7.0 on your local system. Or for manual instructions, see the CalDB Downloads page to install or upgrade your Chandra CalDB to CalDB 4.7.0.

CalDB 4.7.0 includes the following updates:

  • ACIS T_GAIN Epoch 63 (Aug-Oct 2015)
  • ACIS SUBPIX update for CC-mode OBS_IDs
  • ACIS QE Modification for early CC-mode OBS_IDs
  • HRC-I GMAP and PIBGSPEC updates for 2015-16
  • HRC-I BKGRND event lists for 2014, 2015
  • Chandra Cycle 18 PIMMS Effective Areas

See details in the link CalDB 4.7.0 Release Notes.


The CALDB is the directory and indexing structure that stores and provides access to all calibration files that are required for standard processing and analysis.

These files are used in standard data processing, as well as for analysis with software packages such as CIAO. When you apply a gain map, create an exposure map, or build response files (RMFs and ARFs) - among many other things - you are using the Chandra CALDB to apply the necessary calibration files.

The CALDB serves many functions:

  • Storing and archiving calibration files.

  • Maintaining a naming convention and header structure for all calibration files.

  • Indexing calibration data, based on FITS header keywords, for software access.

  • Permitting updates of calibration data independent of software updates, while maintaining configuration control.

  • Providing a traceable history of calibration data in the database by maintaining versioning.

  • Translating calibration products into formats suitable for processing and/or analysis.

These webpages contain information about each of these topics. They are also designed to help you (or your system manager) understand how the CALDB is assembled and how it works in the Chandra software system.


Please email the CXC Helpdesk with any questions or comments on the CALDB and this website.


Last modified: 14 December 2015
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