# Fits file and WCS issue **URL:** \ **Category:** Astropy\ **Created:** [May 27, 2023, 1:52pm UTC](https://community.openastronomy.org/t/fits-file-and-wcs-issue/678 "2023-05-27T13:52:23Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![ngc2218](https://avatars.discourse-cdn.com/v4/letter/n/71e660/32.png) [@ngc2218](https://community.openastronomy.org/u/ngc2218)\ **Post date:** [May 27, 2023, 1:52pm UTC](https://community.openastronomy.org/t/fits-file-and-wcs-issue/678/1 "2023-05-27T13:52:23Z")
Hello, I’ve been trying a simple example with a fits file like this: ```auto from astropy import wcs from astropy.io import fits # Load the FITS hdulist using astropy.io.fits hdulist = fits.open('abell.fits') # Parse the WCS keywords in the primary HDU w = wcs.WCS(hdulist[0].header) # Print out the "name" of the WCS, as defined in the FITS header print(w.wcs.name) # Print out all of the settings that were parsed from the header w.wcs.print_contents() ``` And I get an error: ```auto ValueError Traceback (most recent call last) Cell In[34], line 8 5 hdulist = fits.open('abell.fits') 7 # Parse the WCS keywords in the primary HDU ----> 8 w = wcs.WCS(hdulist[0].header) 10 # Print out the "name" of the WCS, as defined in the FITS header 11 print(w.wcs.name) File ~\AppData\Local\Programs\Python\Python311\Lib\site-packages\astropy\wcs\wcs.py:612, in WCS. __init__ (self, header, fobj, key, minerr, relax, naxis, keysel, colsel, fix, translate_units, _do_set) 609 self.fix(translate_units=translate_units) 611 if _do_set: --> 612 self.wcs.set() 614 for fd in close_fds: 615 fd.close() ValueError: ERROR 5 in wcsset() at line 2775 of file cextern\wcslib\C\wcs.c: Invalid parameter value. ERROR 4 in linset() at line 737 of file cextern\wcslib\C\lin.c: Failed to initialize distortion functions. ERROR 3 in dssset() at line 2697 of file cextern\wcslib\C\dis.c: Coefficient scale for DSS on axis 1 is zero.. ``` Part of my fits header: ```auto OBJCTRA = '16 35 53.453 ' /Object Right Ascension (J2000) OBJCTDEC= '+66 14 01.11 ' /Object Declinaison (J2000) RA = 2.48972721654300130E+002 /Telescope RA DEC = 6.62336441336017145E+001 /Telescope DEC CRVAL1 = 2.48972721654300130E+002 /approx coord. in RA CRVAL2 = 6.62336441336017145E+001 /approx coord. in DEC CDELT1 = 2.57895481677548606E-004 /ScaleX in deg/pix CDELT2 = 2.57895481677548606E-004 /ScaleY in deg/pix ``` Any idea how to remedy this? As an update, I solved the image using [astrometry.net](http://astrometry.net) and downloaded the new fits file with all WCS data added. Still doesn’t work. ```auto from astropy import wcs from astropy.io import fits # Load the FITS hdulist using astropy.io.fits img = fits.open('abell_solved_wcs.fits') # Parse the WCS keywords in the primary HDU w = wcs.WCS(img[0].header,img) ``` Error: ```auto ValueError: ERROR 5 in wcsset() at line 2775 of file cextern\wcslib\C\wcs.c: Invalid parameter value. ERROR 4 in linset() at line 737 of file cextern\wcslib\C\lin.c: Failed to initialize distortion functions. ERROR 3 in dssset() at line 2697 of file cextern\wcslib\C\dis.c: Coefficient scale for DSS on axis 1 is zero.. ``` ---
**Author:** ![hamogu](https://dub1.discourse-cdn.com/flex005/user_avatar/community.openastronomy.org/hamogu/32/93_2.png) [@hamogu](https://community.openastronomy.org/u/hamogu)\ **Post date:** [June 10, 2023, 11:51pm UTC](https://community.openastronomy.org/t/fits-file-and-wcs-issue/678/2 "2023-06-10T23:51:05Z")
That could be a bug in astropy, or it could be an error in your fits file. I can’t say from the few lines of the fits header that you posted. Could you make the complete file available somewhere, e.g. Dropbix, Google drive etc. so that I can download it and look at the entire header?