American Association of Variable Star Observers (AAVSO)
Thu, 06/19/2014 - 15:30

I'm new at CCD photometry.  Just starting to use VPHOT and love it!  Well done.  I was calibrating my images in CCDOps and then uploading the calibrated images.  Is it possible to upload my master bias, dark, and flat frames into VPHOT to calibrate in the "cloud"?  If so, can you walk me through the necessary steps?  Thanks,

 - Dave Cowall (cwd)

vphot calibration

Hi Dave,

Unfortunately, VPHOT is an analysis program, not an image processing program.  We've avoided all processing steps like flat-fielding and dark subtraction.  That needs to be done to your images before they are uploaded.  Thanks for the kind words about VPHOT!


American Association of Variable Star Observers (AAVSO)


VPhot doesn't do image calibration, and it doesn't know your images are calibrated unless it sees certain lines in the FITS header.   Lacking that, it reports your images as uncalibrated-  a non-green box in the "Cal" column of the Available Images page.

CCDSoft doesn't add that line to the FITS header automatically, nor does AIP.  As things stand now if you want your data reported as calibrated (and you're using CCDSoft or AIP to calibrate) you have to edit the FITS headers yourself.  Look in the next item down in this forum's topics list ("images showing as not calibrated").

Phil Sullivan