How to Cite JWST Data Processing Versions and Reference Files

Guidelines for how to cite the data processing versions and calibration reference files in publications are covered in this article. 

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Information on how to cite your JWST data processing versions and associated calibration reference files is provided below. This information is helpful for future researchers who wish to reproduce the results and retrospectively assess possible discrepancies with data processed using different versions of the JWST Operational Pipeline and reference files.

Data processing 

JWST Science Data Processing

The JWST Science Data Processing (SDP) subsystem is the software that generates the raw data products ("uncal"). This software undergoes periodic updates and fixes along with the other data processing software; therefore, it is important to include the version used to generate the data in publications. The version is captured in the header keyword SDP_VER. (e.g., "2022_3").

JWST Science Calibration Pipeline 

The JWST Science Calibration Pipeline is the software that processes data from all instruments and observing modes to generate fully calibrated individual exposures and high level data products (mosaics, extracted spectra, etc.). Because of the dynamic nature of the science calibration pipeline, it is important to include the version used to generate the data in publications. The science calibration pipeline version is captured in the header keyword CAL_VER (e.g., "1.7.2"). 

Observers who wish to cite the JWST Science Calibration Pipeline software itself can use the Digital Object Identifier (DOI) on Zenodo.

Data processing with a modified pipeline

Some observers may choose to process their data manually using modified versions of the science calibration pipeline and parameters in the calibration steps. Because changing the default calibration pipeline steps or parameters may produce different results, it is important to share this information in publications by describing (for example) which parameters to change for certain calibration steps, or by pointing to code or Jupyter notebooks stored in a public hosting service for software, such as GitHub. 

Calibration reference files

CRDS context

All calibration reference files used in the science calibration pipeline are stored in the Calibration Reference Data System (CRDS), and the CRDS context defines the set of rules used to select the best reference files for an instrument and mode. Throughout the life of the mission, and in particular during Cycle 1, instrument teams will continue to analyze calibration data to update and deliver in-flight reference files, as needed. Because the reference files will be periodically updated, publications should include the CRDS context version used for data processing. This version is captured in the header keyword CRDS_CTX (e.g., "jwst_0955.pmap").

CRDS server

Publications using data reprocessed locally and calibrated before November 10, 2022, should also provide the CRDS server used to retrieve the calibration reference data, either CRDS-PUB or CRDS-OPS, because these servers may provide different reference file versions. For data going into the MAST, the CRDS OPS server will always be used. The CRDS PUB server was set up in anticipation of rapid reference file updates during commissioning and Cycle 1; however, due to the trouble-free commissioning process and the smooth transition to science operations, it has been decided that the PUB server is no longer needed and it will be decommissioned on March 1, 2023. The institute will retain an internal archive of the maps and calibration reference files, so observers who wish to use any files from the CRDS PUB server in future will need to file a JWST Pipeline help desk ticket to access the information. Including the name of the CRDS server along with the data processing software versions in your publications will help ensure reproducibility for future data processing and analysis. 

Observers who wish to cite the CRDS software system itself can reference Greenfield & Miller (2016).


Greenfield, P., & Miller, T. 2016, Astron. Comput., 16, 41 (ADS) 
The Calibration Reference Data System

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Originally published