GWCS Documentation

Getting GWCS

To install the latest release:

pip install gwcs

To install as a conda package from conda-forge:

conda install -c conda-forge gwcs

To install the latest development version from source (not generally recommendedß unless one needs a very new feature or bug fix):

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

Introductions

For Users

• Using Generalized World Coordinate System Models
  • Brief Introduction and Outline
  • User Perspective
    • Terminology and Conventions
    • Simple Image Use
    • Use with Spectra
    • Simple Slit Case
    • Narrowing General Transforms
    • Modifying Transforms / Using Intermediate Frames
    • A Notes about Performance
    • Saving and Reading GWCS Objects
  • Motivations for GWCS
    • HST WCS Headaches
    • Advantages of GWCS

Constructing GWCS Models

• Introduction to Constructing Generalized World Coordinate System Models
  • Pixel Conventions and Definitions
  • Basic Structure of a GWCS Object
    • A step-by-step example of constructing an imaging GWCS object.
• Adding distortion to the imaging example
• An IFU Example - managing a discontiguous WCS
  • Using a pixel to slice mapping
  • Custom model storing transforms in a dictionary

Advanced User Topics

• Shared Interface for World Coordinate System - APE 14
• Native Interface
• Differences in functionality between the Native and Shared interfaces
• Using the WCS object
  • Inspecting Available Coordinate Frames
  • Using Bounding Box
  • Manipulating Transforms
  • Inverse Transformations
• WCS User Tools
• Listing of imaging_wcs.asdf
• WCS validation
• Fitting a WCS to input pixels & sky positions
• FITS Equivalent WCS Example

Reference

• Change Log
  • 1.0.3 (2026-02-12)
    • Bug Fixes
  • 1.0.2 (2026-02-11)
    • Bug Fixes
  • 1.0.1 (2026-01-22)
    • Bug Fixes
  • Legacy Change Log
    • 1.0.0 (2026-01-15)
    • 0.26.1 (2025-11-19)
    • 0.26.0 (2025-09-18)
    • 0.25.1 (2025-06-20)
    • 0.25.0 (2025-06-19)
    • 0.24.0 (2025-02-04)
    • 0.23.0 (skipped)
    • 0.22.0 (2024-12-19)
    • 0.21.0 (2024-03-10)
    • 0.20.0 (2023-11-29)
    • 0.19.0 (2023-09-15)
    • 0.18.3 (2022-12-23)
    • 0.18.2 (2022-09-07)
    • 0.18.1 (2022-03-15)
    • 0.18.0 (2021-12-22)
    • 0.17.1 (2021-11-27)
    • 0.17.0 (2021-11-17)
    • 0.16.1 (2020-12-20)
    • 0.16.0 (2020-12-18)
    • 0.15.0 (2020-11-13)
    • 0.14.0 (2020-08-19)
    • 0.13.0 (2020-03-26)
    • 0.12.0 (2019-12-24)
    • 0.11.0 (2019/07/26)
    • 0.10.0 (12/20/2018)
    • 0.9.0 (2018-05-23)
    • 0.8.0 (2017-11-02)
    • 0.7 (2016-12-23)
    • 0.5.1 (2016-02-01)
    • 0.5 (2015-12-28)
• API
  • gwcs.wcs Package
    • Classes
    • Class Inheritance Diagram
  • gwcs.coordinate_frames Package
    • axes_order and conversion between objects and arguments
    • Functions
    • Classes
    • Class Inheritance Diagram
  • gwcs.wcstools Module
    • Functions
  • gwcs.selector Module
    • Classes
    • Class Inheritance Diagram
  • gwcs.spectroscopy Module
    • Classes
    • Class Inheritance Diagram
  • gwcs.geometry Module
    • Classes
    • Class Inheritance Diagram

See also

• The modeling package in astropy

• The coordinates package in astropy

• The Advanced Scientific Data Format (ASDF) standard and its Python implementation