James Webb Space Telescope Calibration Pipeline

Version: 3.1.0.dev162+g0ec8bb255

This package (jwst) processes uncalibrated data from both imagers and spectrographs onboard the James Webb Space Telescope (JWST), an orbiting infrared observatory stationed at Earth-Sun L ₂. The pipeline performs a series of calibration steps that result in standard data products, applying various corrections to produce science-ready, calibrated output products including individual exposures and high-level data products (mosaics, extracted spectra, etc.).

See README.md for installation and usage instructions.

This package allows users to run and configure the calibration pipeline themselves for custom processing of JWST data, either from the command line with strun or from Python with pipeline and step functions and classes in the jwst package (see this curated set of Jupyter notebooks for example usage). Additionally, the jwst package provides JWST datamodel classes, the recommended method for reading and writing JWST data files in Python.

Note

If you have trouble installing this package, have encountered a bug while running the pipeline, or wish to request a new feature, please open an issue on GitHub or contact the JWST Help Desk.

Detailed explanations of specific calibration stages, reference files, and pipeline builds can be found on JDox.

Attention

Starting December 1st 2026, STScI will no longer test macOS x86 versions of software (Intel processors, including all Mac machines earlier than 2020). macOS x86 builds will still be available on PyPI and installable with pip install, but will not be tested for numerical accuracy.

Going forward, software testing for macOS will only be ARM64 (Apple Silicon).

Contributing

jwst is an open source package written in Python. The source code is available on GitHub. New contributions and contributors are very welcome!

Please read CONTRIBUTING.md, the public API definition, and the public API deprecation policy.

We strive to provide a welcoming community by abiding with our CODE_OF_CONDUCT.md.

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User Documentation

• Introduction to the JWST Pipeline
  • Introduction
  • Overview of Pipeline Code
• Reference Files, Parameter Files and CRDS
  • Reference Files
  • Parameter Files
  • CRDS
• Parameters
  • Universal Parameters
  • Pipeline/Step Parameters
• Running the JWST pipeline: Python Interface
  • Overview of Running the Pipeline in Python
  • Configuring a Pipeline/Step in Python
  • Controlling Output File Behavior
  • Advanced use - pipeline.run() vs. pipeline.call
• Running the JWST pipeline: Command Line Interface (strun)
  • CRDS Environment Variables
  • Overview of Running the Pipeline with strun
  • Exit Status
  • Setting Step Parameters on a Pipeline or Individual Step
  • Overriding Reference Files
  • Skipping a Pipeline Step
  • Saving Intermediate Pipeline Results to a File
  • Setting Output File Name
  • Setting Output File Directory
• Running the JWST pipeline: Multiprocessing
  • Multiprocessing within a pipeline step
  • Multiprocessing on multiple observations
• Available Pipelines
  • Pipeline/Step Suffix Definitions
  • For More Information
• Input and Output File Conventions
  • Input Files
  • Output Files
• Background Subtraction Methods
  • Introduction
  • Imaging Mode
  • Spectroscopic Modes
  • Image-from-Image Subtraction
  • Master Background Subtraction
• Logging
  • DataModel cal_logs
  • Configuration
• JWST Datamodels
  • Datamodels and the JWST pipeline
  • Groups of Datamodels
• More Information for JWST Users
  • Versioning Scheme
  • API: Public vs Private
  • API Deprecation Policy

Data Products

• Data Products Information
  • Processing Levels and Product Stages
  • File Naming Schemes
  • Data Product Types
  • Common Features
  • Science products
  • Non-science products
  • MSA Metadata File: msa
  • Guide star data products
  • Migrating deprecated products

Error Propagation

• Error Propagation
  • Description
  • Stage 1 Pipelines
  • Stage 2 Pipelines
  • Stage 3 pipelines

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Package Structure

• Package Index
  • Adaptive Trace Model
  • Align PSF References
  • AMI Analyze
  • AMI Normalize
  • Assign Moving Target WCS
  • Assign WCS
  • Associations
  • Background Subtraction
  • Bad Pixel Self-Calibration
  • Barshadow Correction
  • Charge Migration
  • Clean Flicker Noise
  • Combine 1D Spectra
  • Cube Building
  • Dark Current Subtraction
  • Data Quality (DQ) Initialization
  • EMI Correction for MIRI
  • Exposure to Source Conversion
  • Extract 1D Spectra
  • Extract 2D Spectra
  • First Frame Correction
  • Flatfield Correction
  • Fringe Correction
  • Gain Scale Correction
  • Group Scale Correction
  • Guider CDS Processing
  • HLSP Processing
  • Imprint Subtraction
  • IPC Correction
  • Jump Detection
  • KLIP Processing
  • Library Utilities
  • Last Frame Correction
  • Linearity Correction
  • Master Background Subtraction
  • Model Blender
  • MSAFlagOpen Correction
  • Outlier Detection
  • Pathloss Correction
  • Persistence Correction
  • Photometric Calibration
  • Picture Frame Correction
  • Pipeline Modules
  • Pixel Replacement
  • Ramp Fitting
  • Reference File Information
  • Reference Pixel Correction
  • Resampling Imaging Data
  • Resampling Spectral Data
  • Reset Correction
  • Residual Fringe
  • Reset Switch Charge Decay (RSCD) Correction
  • Saturation Detection
  • SkyMatch
  • Source Catalog
  • Spectral Leak
  • Source Type (SRCTYPE) Determination
  • Stack PSF References
  • STPIPE
  • Stray Light Correction
  • Superbias Subtraction
  • Target Centroiding Step
  • TSO Aperture Photometry
  • TweakReg
  • Wavelength Correction
  • WFS Combine
  • WFSS Contamination Correction
  • White Light Curve Generation
• Change Log
  • 3.1.0.dev162+g0ec8bb255 (2026-11-09)
  • 3.0.0 (2026-06-23)
  • 2.0.1 (2026-05-06)
  • 2.0.0 (2026-04-13)
  • 1.20.2 (2025-10-31)
  • 1.20.1 (2025-10-20)
  • 1.20.0 (2025-09-23)
  • 1.19.2 (2025-09-11)
  • 1.19.1 (2025-07-21)
  • 1.19.0 (2025-06-26)
  • 1.18.0 (2025-04-08)
  • 1.17.1 (2025-01-02)
  • 1.17.0 (2024-12-20)
  • 1.16.1 (2024-10-30)
  • 1.16.0 (2024-09-20)
  • 1.15.1 (2024-07-08)
  • 1.15.0 (2024-06-26)
  • 1.14.0 (2024-03-29)
  • 1.13.4 (2024-01-25)
  • 1.13.3 (2024-01-05)
  • 1.13.2 (2023-12-21)
  • 1.13.1 (2023-12-19)
  • 1.13.0 (2023-12-15)
  • 1.12.5 (2023-10-19)
  • 1.12.4 (2023-10-12)
  • 1.12.3 (2023-10-03)
  • 1.12.2 (2023-10-02)
  • 1.12.1 (2023-09-26)
  • 1.12.0 (2023-09-18)
  • 1.11.4 (2023-08-14)
  • 1.11.3 (2023-07-17)
  • 1.11.2 (2023-07-12)
  • 1.11.1 (2023-06-30)
  • 1.11.0 (2023-06-21)
  • 1.10.2 (2023-04-14)
  • 1.10.1 (2023-04-13)
  • 1.10.0 (2023-04-03)
  • 1.9.6 (2023-03-09)
  • 1.9.5 (2023-03-02)
  • 1.9.4 (2023-01-27)
  • 1.9.3 (2023-01-12)
  • 1.9.2 (2023-01-04)
  • 1.9.1 (2023-01-03)
  • 1.9.0 (2022-12-27)
  • 1.8.5 (2022-12-12)
  • 1.8.4 (2022-11-15)
  • 1.8.3 (2022-11-11)
  • 1.8.2 (2022-10-20)
  • 1.8.1 (2022-10-17)
  • 1.8.0 (2022-10-10)
  • 1.7.2 (2022-09-12)
  • 1.7.1 (2022-09-07)
  • 1.7.0 (2022-09-01)
  • 1.6.2 (2022-07-19)
  • 1.6.1 (2022-07-15)
  • 1.6.0 (2022-07-11)
  • 1.5.3 (2022-06-20)
  • 1.5.2 (2022-05-20)
  • 1.5.1 (2022-05-17)
  • 1.5.0 (2022-05-05)
  • 1.4.6 (2022-03-25)
  • 1.4.5 (2022-03-23)
  • 1.4.4 (2022-03-16)
  • 1.4.3 (2022-02-03)
  • 1.4.2 (2022-01-20)
  • 1.4.1 (2022-01-15)
  • 1.4.0 (2022-01-10)
  • 1.3.3 (2021-10-05)
  • 1.3.2 (2021-09-03)
  • 1.3.1 (2021-08-09)
  • 1.3.0 (2021-07-31)
  • 1.2.3 (2021-06-08)
  • 1.2.2 (2021-06-08)
  • 1.2.1 (2021-06-07)
  • 1.2.0 (2021-05-24)
  • 1.1.0 (2021-02-26)
  • 1.0.0 (2021-02-22)
  • 0.18.3 (2021-01-25)
  • 0.18.2 (2021-01-19)
  • 0.18.1 (2021-01-08)
  • 0.18.0 (2020-12-21)
  • 0.17.1 (2020-09-15)
  • 0.17.0 (2020-08-28)
  • 0.16.2 (2020-06-10)
  • 0.16.1 (2020-05-19)
  • 0.16.0 (2020-05-04)
  • 0.15.1 (2020-03-10)
  • 0.15.0 (2020-02-28)
  • 0.14.2 (2019-11-18)
  • 0.14.1 (2019-11-11)
  • 0.14.0 (2019-10-25)
  • 0.13.7 (2019-06-21)
  • 0.13.6 (2019-06-20)
  • 0.13.5 (2019-06-19)
  • 0.13.4 (2019-06-17)
  • 0.13.3 (2019-06-04)
  • 0.13.2 (2019-05-14)
  • 0.13.1 (2019-03-07)
  • 0.13.0 (2019-02-15)
  • 0.12.3 (2019-01-10)
  • 0.12.2 (2018-11-15)
  • 0.12.1 (2018-10-30)
  • 0.11.0 (2018-09-10)
  • 0.10.0 (2018-07-30)