The processing of JWST data goes through 3 stages. Stage 1 processes the raw data to produce count rate (slope) images. Stage 2 calibrates the slope images. Stage 3 carries out additional processing, including the ability to work with multiple exposures to create combined images and spectra..

Science calibration pipeline stages

See also: JWST Data Calibration Considerations, Algorithm Documentation, Understanding JWST Data Files, JWST Science Calibration Pipeline Overview 

There are 3 main calibration pipeline stages required to completely process a set of exposures for a given observation:

• Stage 1: Apply detector-level corrections to the raw data for individual exposures and produce count rate (slope) images from the "ramps" of non-destructive readouts
• Stage 2: Apply physical corrections (e.g., slit loss) and calibrations (e.g., absolute fluxes and wavelengths) to individual exposures
• Stage 3: Combine the fully calibrated data from multiple exposures

The JWST Science Calibration Pipeline has 3 main stages that provide data to the Archive (see Figure 1).  Each stage is composed of multiple steps (i.e., modules), which differ according to the type of observation. A summary of the input and output data for each stage are shown below, along with the type of observations that are run through the different modules.

Stage 1

This stage applies detector-level corrections to raw non-destructively read "ramps" in order to produce count rate images per exposure, or per integration for some modes.

• Input: raw ramps for all integrations
• Output: uncalibrated slope images for all integrations and exposures
• calwebb_detector1: applied for all data

Stage 2

See also: JWST Data Associations

This stage applies physical corrections and calibrations to individual exposures to produce fully calibrated (unrectified) exposures.

• input: uncalibrated slope images for all integrations and exposures
• output: calibrated slope images for all integrations and exposures
• calwebb_image2: applied to all imaging data (including coronagraphy and AMI)
• calwebb_spec2: applied to all spectroscopic data

Stage 3

See also: JWST Data Associations

This stage combines the fully calibrated data from multiple exposures.

• input: calibrated slope images for all integrations and exposures
• output: combined, rectified level-3 data
• calwebb_image3: applied to direct imaging data
  • output: coadded image(s) (e.g., mosaic), catalog of sources, updated exposure level products
• calwebb_coron3: applied to coronagraphic data
  • output: coadded image(s), and updated exposure level products
• calwebb_ami3: applied to NIRISS aperture masking interferometry data
  • output: fringe parameters.
• calwebb_spec3: applied to spectroscopic data
  • output: coadded spectral cube, extracted 1D spectrum, and updated exposure level products
• calwebb_tso3: applied to all time-series observations (photometry and spectroscopy)
  • output: photometry and 1D spectroscopy for each integration and exposure, and updated exposure level products

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Stages of processing by observation type

See also: JWST Observing Template

The full list of exposure type versus calibration pipeline stage is shown in the science calibration pipeline software documentation. Table 1 below shows the science calibration pipeline modules used to process the data from each JWST observing template.

Table 1. Science calibration pipeline modules vs. observing template

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