Closed nienie86 closed 7 years ago
Could you please provide a file (or just the header) for the problematic WCS?
This is the header:
SIMPLE = T / file does conform to FITS standard
BITPIX = -32 / number of bits per data pixel
NAXIS = 3 / number of data axes
NAXIS1 = 400 / length of data axis 1
NAXIS2 = 400 / length of data axis 2
NAXIS3 = 1 / length of data axis 3
EXTEND = T / FITS dataset may contain extensions
COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy
COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359H
CTYPE1 = 'RA---SIN'
CTYPE2 = 'DEC--SIN'
CDELT1 = -2.78473963018089E-06
CDELT2 = 2.78473963018089E-06
CRPIX1 = 200.5
CRPIX2 = 200.5
CRVAL1 = 0.
CRVAL2 = 0.
CTYPE3 = 'VELO-LSR'
CDELT3 = 0.
CRPIX3 = 1.
CRVAL3 = 0.
BUNIT = 'K '
OBJECT = 'model '
END
I think CDELT3=0
is what causes the problem. The PC matrix is not specified, so it is internally set to identity. Then it's multiplied by CDELT3 and becomes non-singular. What was the intended use of CDELT3 (the default value is 1)?
I recently upgraded astropy to v1.3, but now I have problems with the WCS module (astropy.wcs.WCS). With some FITS files (but not all) I get the following error:
I cannot figure out what the problem is or how to fix this. Has anyone encountered this issue before?