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Last modified: 31 May 2016


Welcome to the
Chandra Calibration Database Website

The Chandra X-Ray Center has introduced version 4.7.2 of the Chandra Calibration Database (CALDB) on 31 MAY 2016.

The CalDB 4.7.2 upgrade is a patch upgrade to CalDB 4.7.0 and later versions, and is optimized for use with CIAO 4.8.2 and subsequent patches. While CalDB 4.7.2 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 4.7.2 on your local system. Or for manual instructions, see the CalDB Downloads page to install or upgrade your Chandra CalDB to CalDB 4.7.2.

CalDB 4.7.2 includes the following updates, which affect only ACIS GRADED CC-mode observations taken since 2009-11-01T00:00:00:

  • Retraction of ACIS GRADE file N0005
  • Altered ACIS QE_CC file selection

See details in the link CalDB 4.7.2 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: 31 May 2016
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