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Dear reader,I am having some problems getting accurate output from my photometry procedures. Being a rather new user I have attempted to read up where possible and would think I have a decent grasp on relevant IRAF facilities, but unfortunately I'm simply not getting good results.As an example, I've worked on two image files taken of the same region - the Draco dwarf spherical galaxy - but in different filters. I've reduced the images as well as those of standard stars in terms of bias, darks and flat fields. I've then used APPHOT/DAOPHOT (scripted) on the reduced data, and finished off using PHOTCAL to transform to standard magnitudes.However, the results I'm getting are several magnitudes off from documented values. I realize it's a wide open question, but I could really use some help in trying to find where I've gone wrong.Breaking it down a little... I have placed what I think is relevant files on the following path:http://www.acc.umu.se/~anlag/phot/The files are as follows:[code:1:59653ea8c6]Dra_dSph-001_i_1s.fit //the reduced images themselves
Dra_dSph-001_v_1s.fit
Dra_dSph-001_i_1s.fit.als.good //the DAOPHOT/allstar output
Dra_dSph-001_v_1s.fit.als.good
Dra_dSph-001_v_1s.fit.ph.mag //multi-aperture photometry output, for mkapfile
Dra_dSph-001_i_1s.fit.ph.magstd.catalog //catalog data for standard stars
std.imsets //standard star imsets
std.obs //mknobsfile output, standard star observation file
fstd.obs.dat //format file for the obs file
std.config //standard star configuration file
std.params //fitparams output on standard stars
std.calib //invertfit output on standard starsDra-001.cors //mkapfile output on project files, aperture corrections
Dra-001.sets //mkimsets output, project files, correlating images
Dra-001.obs //mkobsfile output, project files
Dra-001.calib //invertfit output, project files, should be standard magnitudes?[/code:1:59653ea8c6]In order to say something about what I DON'T think it is... when I run the PHOTCAL transformations on the standard stars observation file, the output (std.calib) matches reasonably with the catalog data (std.catalog). That would seem to indicate to me that the transformation data itself (std.params, std.config) is okay, which I suppose leaves the initial crowded-field photometry (the *.als.good files), the aperture corrections (*.cors, based on *.ph.mag) or the final stages of transforming the project files (Dra-001.* files).Just to point out a clear indication that something is wrong, the two brightest stars in the final project star output (Dra-001.calib), designated Draco-001-1 and Draco-001-2 respectively, are displayed to have V magnitudes of 2.35 and 2.88 respectively. Looking them up on Simbad, they should actually be at 8.8 and 9.8 magnitudes respectively.Again, I realize this is a rather big question that could take some time to answer comprehensively. However, any small pointer or question would be appreciated. I am continuedly working on sorting this out but this has been the case for some time and unfortunately my lack of margin is running about as short as my access to support at this time.Thus, many thanks to anyone who might offer assistance, if ever so small.Regards/Anders