[AstroPy] Pywcs not reading transformation matrix correctly

Thomas Robitaille thomas.robitaille@gmail....
Thu Jul 26 12:10:07 CDT 2012


Which version of Astropy are you using?

import astropy
print astropy.__version__

I'm using the latest developer version, and it seems to be working:

CD_11  CD_12: -7.7588993045300006e-05 4.5042903792000001e-07
CD_21  CD_22: -3.9690360471000002e-07 -7.7631469153300006e-05
CRVAL    : 343.48506545599997 16.146689138399999
CRPIX    : 1094.26737976 1037.5606839899999
NAXIS    : 0.0 0.0

If you are using v0.1, could you try updating to the latest git
version to see if it was fixed?

Thanks!
Tom

On 26 July 2012 19:03, Oliver King <ogk@astro.caltech.edu> wrote:
> Hi JB,
>
> The WCS does not have a RADECSYS keyword; the CTYPE is TAN-SIP. Here are all the WCS parameters (excluding the polynomial coefficients). This is an image which has had a WCS attached by the astrometry.net software.
>
> CTYPE1  = 'RA---TAN-SIP' / TAN (gnomic) projection + SIP distortions
> CTYPE2  = 'DEC--TAN-SIP' / TAN (gnomic) projection + SIP distortions
> WCSAXES =                    2 / no comment
> EQUINOX =               2000.0 / Equatorial coordinates definition (yr)
> LONPOLE =                180.0 / no comment
> LATPOLE =                  0.0 / no comment
> CRVAL1  =        343.485065456 / RA  of reference point
> CRVAL2  =        16.1466891384 / DEC of reference point
> CRPIX1  =        1094.26737976 / X reference pixel
> CRPIX2  =        1037.56068399 / Y reference pixel
> CUNIT1  = 'deg     ' / X pixel scale units
> CUNIT2  = 'deg     ' / Y pixel scale units
> CD1_1   =   -7.75889930453E-05 / Transformation matrix
> CD1_2   =     4.5042903792E-07 / no comment
> CD2_1   =    -3.9690360471E-07 / no comment
> CD2_2   =   -7.76314691533E-05 / no comment
> IMAGEW  =                 2048 / Image width,  in pixels.
> IMAGEH  =                 2048 / Image height, in pixels.
>
> Cheers,
> Oliver
>
> On Jul 26, 2012, at 9:58 AM, Jean-Baptiste Marquette wrote:
>
>>
>> Hi Oliver,
>>
>>> Is this a known bug? Is there a workaround or do I need to manually edit my FITS file headers?
>>
>> What are your CTYPEn and RADECSYS ?
>>
>> Cheers
>> JB
>
> ------
> Oliver King
> Astronomy Department, Caltech
> +1-626-395-4197
>
> _______________________________________________
> AstroPy mailing list
> AstroPy@scipy.org
> http://mail.scipy.org/mailman/listinfo/astropy


More information about the AstroPy mailing list