[bug #62052] WCS decomposition of CD into PC+CDELT not setting interanal values

[Mohammad Akhlaghi]

URL:
  <https://savannah.gnu.org/bugs/?62052>

                 Summary: WCS decomposition of CD into PC+CDELT not setting
interanal values
                 Project: GNU Astronomy Utilities
            Submitted by: makhlaghi
            Submitted on: Mon 14 Feb 2022 11:30:57 AM UTC
                Category: Libraries
                Severity: 3 - Normal
              Item Group: Output not reasonable
                  Status: In Progress
                 Privacy: Public
             Assigned to: makhlaghi
             Open/Closed: Open
         Discussion Lock: Any

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Details:

The 'gal_wcs_decompose_pc_cdelt' function is in charge of making sure that the
'wcsprm' structure has a PC+CDELT rotation matrix, irrespective of the input
file's keywords. 

This function updates the respective matrices inside the 'wcsprm' structure,
but it doesn't call the 'wcsset' function on the modified structure. As a
result, WCSLIB's internal values won't be updated, and thus none of the
calculations will be affected (including converting RA,Dec to pixel
coordinates). 

To reproduce the problem with all versions before Gnuastro 0.16.153, you can
run the following commands. Note how after creating 'good.fits', the positions
are properly reported.


wget
http://galex.stsci.edu/data/GR6/pipe/01-vsn/05038-NGA_NGC1052/d/01-main/0001-img/07-try/NGA_NGC1052-nd-int.fits.gz

echo 40.097200 -8.432200 | asttable -c'arith $1 $2 wcs-to-img'
--wcsfile=NGA_NGC1052-nd-int.fits.gz  --wcshdu=0

astcrop NGA_NGC1052-nd-int.fits.gz -h0 --mode=img --section=:,:
--output=good.fits

echo 40.097200 -8.432200 | asttable -c'arith $1 $2 wcs-to-img'
--wcsfile=good.fits  --wcshdu=1





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