For a given WCS, return the coordinate frame that matches the celestial component of the WCS.

wcsWCS instance

The WCS to find the frame for

frameBaseCoordinateFrame subclass instance

An instance of a BaseCoordinateFrame subclass instance that best matches the specified WCS.


To extend this function to frames not defined in astropy.coordinates, you can write your own function which should take a WCS instance and should return either an instance of a frame, or None if no matching frame was found. You can register this function temporarily with:

>>> from astropy.wcs.utils import wcs_to_celestial_frame, custom_wcs_to_frame_mappings
>>> with custom_wcs_to_frame_mappings(my_function):
...     wcs_to_celestial_frame(...)