header : string or astropy.io.fits header object.
relax : bool or int, optional
Degree of permissiveness:
- True (default): Admit all recognized informal extensions of the
- False: Recognize only FITS keywords defined by the
published WCS standard.
- int: a bit field selecting specific extensions to accept.
See Header-reading relaxation constants for details.
keysel : sequence of flags, optional
A list of flags used to select the keyword types considered by
wcslib. When None, only the standard image header
keywords are considered (and the underlying wcspih() C
function is called). To use binary table image array or pixel
list keywords, keysel must be set.
Each element in the list should be one of the following strings:
- ‘image’: Image header keywords
- ‘binary’: Binary table image array keywords
- ‘pixel’: Pixel list keywords
Keywords such as EQUIna or RFRQna that are common to
binary table image arrays and pixel lists (including
WCSNna and TWCSna) are selected by both ‘binary’ and