Starting October 9, STScI has changed the way in which calibration reference files are managed through the Calibration Reference Data System (CRDS). Previously, the pipeline software automatically used the most recent reference file version (‘context’) as soon as it was available. Going forward, each version of the pipeline will instead use a specific fixed reference file context that will be updated quarterly with each new release of the calibration pipeline. These changes will affect all new installations of the JWST pipeline software.

All data products obtained through the MAST archive will be reprocessed approximately every 3 months with a consistent set of software and calibration reference files.

For users who reprocess data themselves, all future installations of the JWST calibration pipeline will automatically use its fixed CRDS context, instead of the most-recent one. As a result, it will be both easier to ensure consistent processing of their data and to obtain results which match those available from MAST.

New reference files will continue to be available immediately via CRDS. Users can choose to process their data with these reference files, prior to their use in the next pipeline build, by specifying a particular context number. Note, however, that using a context other than the default recommended for a given pipeline version may result in errors or incorrect results due to possible incompatibilities between software and reference file versions.

Further information about this change can be found on JDox. Please contact the JWST Help Desk with any questions or concerns.