Quickstart Guide

The following is a quickstart guide to installing and running and the latest version of jwst.

In short, the only setup required to run the JWST pipeline is to pip install the jwst package into a conda environment, and then to set correct environment variables for accessing reference files through CRDS. From there, the JWST pipeline can be run in a Python session or with the command line interface, and JWST datamodels and other pipeline utilities can be imported and used in a Python session.

1. Create a conda environment.

Python environments allow you to install different versions of packages and their dependencies and keep them isolated from one another. While there are several possible ways to achieve this (e.g venv), we will use conda in this example.

If you don’t already have conda, please follow the install instructions.

To create a conda environment specifically for the latest stable release of jwst (in this example, called jwst_latest):

conda create --name jwst_latest python=3.11

This will create a new, (nearly) empty Python 3.11 environment in which you can install the jwst package.

2. Install jwst from PyPi

Once you have created your conda environment, make sure it is active by doing:

conda activate jwst_latest

To install the last stable release of jwst, and all its basic dependencies (e.g numpy, stcal):

pip install jwst

For detailed installation instructions, including how to install the development version of jwst from Github or how to install a previous released version, see the Installation page.

3. Set environment variables for Calibration References Data System (CRDS)

CRDS is the system that manages the reference files needed to run the pipeline. Inside the STScI network, the pipeline works with default CRDS setup with no modifications. To run the pipeline outside the STScI network, CRDS must be configured by setting two environment variables:

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

The CRDS_PATH is the directory on your filesystem that contains your local CRDS cache, where reference files are accessed by the pipeline. The CRDS_SERVER_URL variable specifies from which CRDS server reference files should be obtained. For more information, see Reference Files, Parameter Files and CRDS.

4. Running the Pipeline

With jwst installed and CRDS configured for JWST, you can now run the pipeline and use JWST datamodels.

For information on how to run the pipeline using the Python interface, see Running the JWST pipeline: Python Interface.

For information on how to run the pipeline using the command line interface, see Running the JWST pipeline: Command Line Interface.

For information on how to read and write data files with JWST datamodels, see JWST datamodels.