jwst 2.0.0

Library for calibration of science observations from the James Webb Space Telescope

James Webb Space Telescope Calibration Pipeline

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 L₂. The pipeline performs a series of calibration steps that result in standard data products usable for science.

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

[!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.

• Quick Start
  • 1. Install the Pipeline
    • Option: Build Pipeline Directly from Source Code
    • Option: Install Exact Operational Environment
  • 2. Set up the Calibration Reference Data System (CRDS)
  • 3. Run the Pipeline
• Code Contributions
• DMS Operational Build Versions

Quick Start

1. Install the Pipeline

[!IMPORTANT] The JWST calibration pipeline currently supports Linux and macOS. Native Windows builds are not currently supported; use WSL instead.

We recommend using an isolated Python environment to install jwst. Python "environments" are isolated Python installations, confined to a single directory, where you can install packages, dependencies, and tools without cluttering your system Python libraries. You can manage environments with mamba / conda, virtualenv, uv, etc.

These instructions assume you are creating Conda environments with the mamba command (see Miniforge for installation instructions); to use conda instead, simply replace mamba with conda in the following commands.

First, create an empty environment with Python installed:

mamba create -n jwst_env python=3.13

Then, activate that environment (necessary to be able to access this isolated Python installation):

mamba activate jwst_env

Finally, install jwst into the environment:

pip install jwst

Without a specified version, pip defaults to the latest released version that supports your environment. To install a specific version of jwst, explicitly set that version in your pip install command:

pip install jwst==1.20.2

To install a different version of jwst, simply create a new environment for that version:

mamba create -n jwst1.20_env python=3.13
mamba activate jwst1.20_env
pip install jwst==1.20

mamba create -n jwst1.19_env python=3.12
mamba activate jwst1.19_env
pip install jwst==1.19

Option: Build Pipeline Directly from Source Code

[!IMPORTANT] You need a C compiler to build the JWST calibration pipeline (and dependencies) from source.

To install the latest unreleased (and unstable) development version directly from the source code on GitHub:

pip install git+https://github.com/spacetelescope/jwst

Option: Install Exact Operational Environment

There may be occasions where you need to replicate the exact environment used for canonical calibration operations by STScI (e.g. for validation testing or debugging issues). We package releases for operations as environment snapshots that specify exact versions for both the pipeline and all dependencies.

See the DMS Operational Build Versions table for the version of the pipeline corresponding to each operational build. For example, use jwst==1.17.1 for DMS build 11.2. Also note that Linux and macOS systems require different snapshot files:

mamba env create --file https://ssb.stsci.edu/stasis/releases/jwst/JWSTDP-1.18.1/delivery/latest-py312-macos-arm64.yml
mamba activate JWSTDP-1.18.1-1-py312-macos-arm64

[!NOTE] Starting with jwst==1.16.1, the JWST pipeline uses stasis to package environments and deliver releases. If you need a version of jwst prior to 1.16.1, use a slightly different procedure:

mamba create -n jwstdp-1.16.0 --file https://ssb.stsci.edu/releases/jwstdp/1.16.0/conda_python_macos-stable-deps.txt
mamba activate jwstdp-1.16.0
pip install -r https://ssb.stsci.edu/releases/jwstdp/1.16.0/reqs_macos-stable-deps.txt

2. Set up the Calibration Reference Data System (CRDS)

Before running the pipeline, you must first set up your local machine to retrieve files from the Calibration Reference Data System (CRDS) CRDS provides calibration reference files for several telescopes, including JWST.

Set CRDS_SERVER_URL and CRDS_PATH to run the pipeline with access to reference files from CRDS:

export CRDS_SERVER_URL=https://jwst-crds.stsci.edu
export CRDS_PATH=$HOME/data/crds_cache/

[!NOTE] The CRDS PUB Server (https://jwst-crds-pub.stsci.edu) was decommissioned in March 2023. To use historical files from the PUB server, contact the JWST Help Desk.

The pipeline will automatically download individual reference files and cache them in the CRDS_PATH directory. Expect to use 50 gigabytes (or more) of disk space for reference files, depending on the instrument modes in use.

[!TIP] Users within the STScI network do not need to set CRDS_PATH (it defaults to shared network storage).

To use a specific CRDS context other than that automatically associated with a given pipeline version, explicitly set the CRDS_CONTEXT environment variable:

export CRDS_CONTEXT=jwst_1179.pmap

For more information, see the docs page on JWST CRDS reference files.

3. Run the Pipeline

Once installed, the pipeline allows users to run and configure calibration 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.

Code Contributions

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.

See TESTING.md for instructions on automated testing.

DMS Operational Build Versions

The table below provides information on each release of the jwst package and its relationship to software builds used in STScI JWST DMS operations. Each jwst tag was released on PyPI on the date given in Released, and then subsequently installed into operations on the date given in Ops Install.

jwst tag	DMS build	SDP_VER	CRDS_CONTEXT	Released	Ops Install	Notes
2.0.0	B12.3	2026.1.0	1533	2026-04-13		First release candidate for B12.3
1.20.2	B12.1.1	2025.4.1	1464	2025-10-31		Patch release for B12.1.1
1.20.1	B12.1	2025.4.0	1464	2025-10-20		Patch release for B12.1
1.20.0	B12.1	2025.4.0	1462	2025-10-15		First release candidate for B12.1
1.19.2	B12.0.2	2025.3.0	1408	2025-09-11	2025-10-06	Patch release for B12.0.2
1.19.1	B12.0.1	2025.3.0	1408	2025-07-21	2025-08-26	Patch release for B12.0.1
1.19.0	B12.0	2025.3.0	1408	2025-06-26		First release candidate for B12.0
1.18.1	B11.3.1	2025.2.1	1364	2025-06-10		Patch release for B11.3.1
1.18.0	B11.3	2025.2.0	1364	2025-04-01	2025-05-20	First release for B11.3
1.17.1	B11.2	2025.1.0	1321	2025-01-02	2025-03-05	Final release candidate for B11.2
1.17.0	B11.2	2025.1.0	1321	2024-12-20		First release candidate for B11.2
1.16.1	B11.1.1	2024.3.1	1303	2024-11-13	2024-12-06	Final release candidate for B11.1
1.16.0	B11.1	2024.3.0	1298	2024-09-20		First release candidate for B11.1
1.15.1	B11.0	2024.2.2	1293	2024-07-08	2024-09-12	Final release candidate for B11.0
1.15.0	B11.0rc1		1274	2024-06-26		First release candidate for B11.0
1.14.1			1240	2024-06-27		PyPI-only release for external users
1.14.0	B10.2.1	2024.1.1	1240	2024-03-29	2024-06-12	Final release candidate for B10.2.1
1.13.4			1210	2024-01-25		PyPI-only release for external users
1.13.3	B10.1	2023.4.0	1181	2024-01-05		Final release candidate for B10.1
1.13.2	B10.1rc3	2023.4.0	1181	2023-12-21		Third release candidate for B10.1
1.13.1	B10.1rc2	2023.4.0	1181	2023-12-19		Second release candidate for B10.1
1.13.0	B10.1rc1	2023.4.0	1179	2023-12-15		First release candidate for B10.1
1.12.5	B10.0.1	2023.3.1	1166	2023-10-19	2023-12-05	Patch release B10.0.1
1.12.4				2023-10-12		Pinning dependencies for external users
1.12.3	B10.0	2023.3.0	1135	2023-10-03	2023-12-05	Final release candidate for B10.0
1.12.2	B10.0rc3		1135	2023-10-02		Third release candidate for B10.0
1.12.1	B10.0rc2		1132	2023-09-26		Second release candidate for B10.0
1.12.0	B10.0rc1		1130	2023-09-18		First release candidate for B10.0
1.11.4	B9.3.1	2023.2.1	1107	2023-08-14	2023-08-24	Final release for B9.3.1 patch
1.11.3	B9.3	2023.2.0	1097	2023-07-17		Final release candidate for B9.3
1.11.2	B9.3rc3		1097	2023-07-12		Third release candidate for B9.3
1.11.1	B9.3rc2		1094	2023-06-29		Second release candidate for B9.3
1.11.0	B9.3rc1		1094	2023-06-21		First release candidate for B9.3
1.10.2			1077	2023-04-14		Pinning dependencies for external users
1.10.1	B9.2.x	2023.1.1	1077	2023-04-13	2023-05-23	Final release candidate for B9.2
1.10.0	B9.2rc1		1075	2023-03-31		First release candidate for B9.2
1.9.6	B9.1.2	2022.5.2	1068	2023-03-09	2023-03-15	Final release candidate for B9.1.2
1.9.5			1061	2023-03-02		First release candidate for B9.1.2
1.9.4	B9.1.1	2022.5.1	1041	2023-01-27	2023-02-28	Final release candidate for B9.1.1
1.9.3	B9.1	2022.5.0	1030	2023-01-12	2023-02-28	Final release candidate for B9.1
1.9.2	B9.1rc2			2023-01-04		Second release candidate for B9.1 (hotfix)
1.9.1	B9.1rc2			2023-01-03		Second release candidate for B9.1
1.9.0	B9.1rc1			2022-12-27		First release candidate for B9.1
1.8.5	B9.0		1019	2022-12-12		Documentation patch release for B9.0
1.8.4	B9.0			2022-11-16		Documentation patch release for B9.0
1.8.3	B9.0			2022-11-11		Documentation patch release for B9.0
1.8.2	B9.0	2022.4.0	1017	2022-10-19	2022-11-17	Final release candidate for B9.0
1.8.1	B9.0rc2			2022-10-17		Second release candidate for B9.0
1.8.0	B9.0rc1			2022-10-10		First release candidate for B9.0
1.7.2	B8.1.2	2022.3.1	0984	2022-09-12	2022-09-21	Final release candidate for B8.1.2
1.7.1	B8.1.2rc2			2022-09-07		Second release candidate for B8.1.2
1.7.0	B8.1.2rc1			2022-09-01		First release candidate for B8.1.2
1.6.2	B8.1	2022.3.0	0953	2022-07-19	2022-08-19	Final release candidate for B8.1
1.6.1	B8.1rc2			2022-07-15		Second release candidate for B8.1
1.6.0	B8.1rc1			2022-07-11		First release candidate for B8.1
1.5.3	B8.0.1	2022.2.1	0913	2022-06-20	2022-06-30	Patch release B8.0.1
1.5.2	B8.0	2022.2.0	0874	2022-05-20	2022-06-16	Final release candidate for B8.0
1.5.1	B8.0rc2			2022-05-17		Second release candidate for B8.0
1.5.0	B8.0rc1			2022-05-05		First release candidate for B8.0
1.4.6	B7.9.3	2022.1.2	0800	2022-03-25		Final release candidate for B7.9.3
1.4.5	B7.9.3rc2			2022-03-23		Second release candidate for B7.9.3
1.4.4	B7.9.3rc1			2022-03-16		First release candidate for B7.9.3
1.4.3	B7.9.1	2022.1.1	0800	2022-02-03		Final B7.9.1
1.4.2	B7.9	2022.1.0	0797	2022-01-20		Final release candidate for B7.9
1.4.1	B7.9rc2			2022-01-15		Second release candidate for B7.9
1.4.0	B7.9rc1			2022-01-10		First release candidate for B7.9
Pre-launch releases
1.3.3	B7.8.2	2021.4.0	0764	2021-10-05		Same as 1.3.2, but with installation bug fix
1.3.2	B7.8.2	2021.4.0	0764	2021-09-03		Final release candidate for B7.8.2
1.3.1	B7.8.1	2021.3.0	0742	2021-08-09		Final release candidate for B7.8.1
1.3.0	B7.8.1rc1		0741	2021-08-02		First release candidate for B7.8.1
1.2.3	B7.8	2021.2.0	0732	2021-06-08		Final release candidate for B7.8
1.2.2	B7.8rc3			2021-06-08		Third release candidate for B7.8
1.2.1	B7.8rc2			2021-06-07		Second release candidate for B7.8
1.2.0	B7.8rc1		0723	2021-05-24		First release candidate for B7.8
1.1.0	B7.7.1	2021.1.0	0682	2021-02-26		Final release candidate for B7.7.1
1.0.0	B7.7.1rc1		0678	2021-02-22		First release candidate for B7.7.1
0.18.3	B7.7	2020.4.0	0670	2021-01-25		Final release candidate for B7.7
0.18.2	B7.7rc3		0668	2021-01-19		Third release candidate for B7.7
0.18.1	B7.7rc2		0664	2021-01-08		Second release candidate for B7.7
0.18.0	B7.7rc1		0645	2020-12-21		First release candidate for B7.7
0.17.1	B7.6	2020.3.0	0641	2020-09-15		Final release candidate for B7.6
0.17.0	B7.6rc1		0637	2020-08-28		First release candidate for B7.6
0.16.2	B7.5	2020.2.0	0619	2020-06-10		Same as 0.16.1, but with installation bug fix
0.16.1	B7.5	2020.2.0	0619	2020-05-19		Final release candidate for B7.5
0.16.0	B7.5rc1		0614	2020-05-04		First release candidate for B7.5
0.15.1	B7.4.2	2020.1.0	0586	2020-03-10		Final release candidate for B7.4.2
0.15.0	B7.4.2rc1		0585	2020-02-28		First release candidate for B7.4.2
0.14.2	B7.4	2019.3.0	0570	2019-11-18		Final release candidate for B7.4
0.14.1	B7.4rc2		0568	2019-11-11		Second release candidate for B7.4
0.14.0	B7.4rc1		0563	2019-10-25		First release candidate for B7.4
0.13.8	B7.3.1	2019.2.0	0541	2019-09-05		Patch for Build 7.3 released as Build 7.3.1
0.13.7	B7.3	2019.1.0	0535	2019-06-21		Final release candidate for Build 7.3
0.13.6	B7.3rc4		0534	2019-06-20		Fourth release candidate for Build 7.3
0.13.5	B7.3rc3		0534	2019-06-19		Third release candidate for Build 7.3
0.13.4	B7.3rc2		0534	2019-06-18		Second release candidate for Build 7.3
0.13.3	B7.3rc1		0532	2019-06-04		First release candidate for Build 7.3
0.13.2			0500	2019-05-14		DMS test, no delivery to I&T
0.13.1			0500	2019-03-08		DMS test, no delivery to I&T
0.13.0			0500	2019-02-15		DMS test, no delivery to I&T
0.12.3	B7.2.1		0500	2019-01-15		DMS Build 7.2.1 patch release
0.12.2	B7.2	2018_2	0495	2018-11-07		Final release candidate for Build 7.2
0.12.1	B7.2rc2		0495	2018-11-01		Second release candidate for Build 7.2
0.12.0	B7.2rc1		0493	2018-10-09		First release candidate for Build 7.2
0.11.0			0482	2018-09-10		DMS test, no delivery to I&T
0.10.0			0477	2018-07-31		DMS test, no delivery to I&T
0.9.6	B7.1.3	2018_1	0468	2018-06-08		Final release candidate for Build 7.1.3
0.9.5	B7.1.3rc3		0468	2018-06-06		Third release candidate for Build 7.1.3
0.9.4	B7.1.3rc2		0463	2018-05-29		Second release candidate for Build 7.1.3
0.9.3	B7.1.3rc1		0457	2018-05-11		First release candidate for Build 7.1.3
0.9.2			0441	2018-03-28		DMS test, no delivery to I&T
0.9.1			0432	2018-02-16		DMS test, no delivery to I&T
0.9.0	B7.1.2		0422	2017-12-22		DMS patch release to I&T 2018-02-15
0.8.0	B7.1.1		0422	2017-11-06		DMS patch release to I&T 2018-01-17
0.8.0	B7.1	2017_1	0422	2017-11-06		Final release for Build 7.1
0.7.7	B7.0	2016_2	0303	2016-12-13		Final release for Build 7.0