Re: Extracting green channel from FITS

Posted by Bill Tschumy on Mar 01, 2022; 7:39pm
URL: http://astroimagej.170.s1.nabble.com/Extracting-green-channel-from-FITS-tp1750p1798.html

Karen,

Thanks so much for adding this. My initial tests suggests it is not working quite like ASTAP (not sure who is in error, or if the difference matters).  Using a single FITS file, I extracted the Green component in both programs and they do not give the same values at various locations in the image.  Not sure what to make of that.  The ASTAP converted file has greater values in general.

I saved the FITS headers from the generated files.  They differ in things like NAIXS1, NAXIS2 and XPIXSZ indicating you are not handling the extraction the same way.

ETA: Ooops, I was looking at the wrong AIJ header.  I have re-uploaded the correct one.  The NAXIS1 and NAXIS2 now agreed but there is a different in the binning and pixel size.  Again, I'm not sure if this matters in the end.  Yet the two file do nota green on pixel values at the same locations.

Header from ASTAP
ASTAP_header.txt

Hear from AIJ
AIJ_header.txt