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GWCS - Generalized World Coordinate System

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Generalized World Coordinate System (GWCS) is an Astropy affiliated package providing tools for managing the World Coordinate System of astronomical data.

GWCS takes a general approach to the problem of expressing transformations between pixel and world coordinates. It supports a data model which includes the entire transformation pipeline from input coordinates (detector by default) to world coordinates. It is tightly integrated with Astropy.

  • Transforms are instances of astropy.Model. They can be chained, joined or combined with arithmetic operators using the flexible framework of compound models in astropy.modeling.
  • Celestial coordinates are instances of astropy.SkyCoord and are transformed to other standard celestial frames using astropy.coordinates.
  • Time coordinates are represented by astropy.Time and can be further manipulated using the tools in astropy.time
  • Spectral coordinates are astropy.Quantity objects and can be converted to other units using the tools in astropy.units.

For complete features and usage examples see the documentation site.


Beginning with version 0.9 GWCS requires Python 3.5 and above.


To install:

pip install gwcs  # Make sure pip >= 9.0.1 is used.

To clone from github and install the master branch:

git clone
cd gwcs
python install

Contributing Code, Documentation, or Feedback

We welcome feedback and contributions to the project. Contributions of code, documentation, or general feedback are all appreciated. Please follow the contributing guidelines to submit an issue or a pull request.

We strive to provide a welcoming community to all of our users by abiding to the Code of Conduct.

Citing GWCS

If you use GWCS, please cite the package via its Zenodo record.


Generalized World Coordinate System: provides tools for managing WCS in a general way




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