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# celestial_frame_to_wcs

astropy.wcs.utils.celestial_frame_to_wcs(frame, projection='TAN')

  For a given coordinate frame, return the corresponding WCS object.

  Note that the returned WCS object has only the elements corresponding to coordinate frames set (e.g. ctype, equinox, radesys).

  Parameters:
    frame `BaseCoordinateFrame` subclass instance

      An instance of a `BaseCoordinateFrame` subclass instance for which to find the WCS

    projection `python:str`

      Projection code to use in ctype, if applicable

  Returns:
    wcs `WCS` instance

      The corresponding WCS object

  Notes

  To extend this function to frames not defined in astropy.coordinates, you can write your own function which should take a `BaseCoordinateFrame` subclass instance and a projection (given as a string) and should return either a WCS instance, or `None` if the WCS could not be determined. You can register this function temporarily with:

      >>> from astropy.wcs.utils import celestial_frame_to_wcs, custom_frame_to_wcs_mappings
      >>> with custom_frame_to_wcs_mappings(my_function):
      ...     celestial_frame_to_wcs(...)

  Examples

      >>> from astropy.wcs.utils import celestial_frame_to_wcs
      >>> from astropy.coordinates import FK5
      >>> frame = FK5(equinox='J2010')
      >>> wcs = celestial_frame_to_wcs(frame)
      >>> wcs.to_header()
      WCSAXES =                    2 / Number of coordinate axes
      CRPIX1  =                  0.0 / Pixel coordinate of reference point
      CRPIX2  =                  0.0 / Pixel coordinate of reference point
      CDELT1  =                  1.0 / [deg] Coordinate increment at reference point
      CDELT2  =                  1.0 / [deg] Coordinate increment at reference point
      CUNIT1  = 'deg'                / Units of coordinate increment and value
      CUNIT2  = 'deg'                / Units of coordinate increment and value
      CTYPE1  = 'RA---TAN'           / Right ascension, gnomonic projection
      CTYPE2  = 'DEC--TAN'           / Declination, gnomonic projection
      CRVAL1  =                  0.0 / [deg] Coordinate value at reference point
      CRVAL2  =                  0.0 / [deg] Coordinate value at reference point
      LONPOLE =                180.0 / [deg] Native longitude of celestial pole
      LATPOLE =                  0.0 / [deg] Native latitude of celestial pole
      RADESYS = 'FK5'                / Equatorial coordinate system
      EQUINOX =               2010.0 / [yr] Equinox of equatorial coordinates