WCS parameters meaning

[lkosz]

Hello

Is there a documentation explaining the meaning of the parameters in wcs files?

[dstndstn]

Hi, The standards documents are here, https://fits.gsfc.nasa.gov/fits_wcs.html Short version: we use a TAN WCS projection, ie, a tangent-plane projection. CRPIX tells you where on the image the projection is centered CRVAL tells you the RA,Dec of that point. the CD matrix tells you how pixels project into the directions of RA and Dec; those vectors ("intermediate world coordinates") get projected back onto the sphere to give RA,Dec. cheers, --dustin

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