Talked with Dave this morning about diagnosing the CMD problems I'm having. He taught me some tricks to use with ds9--WCS matching and some region files stuff. He also sent me some python code to match stars between the two bands.
I didn't get to the match.py but that'll be first up for Monday if not before. I wrote some code to make my own region files and overplotted them onto the images in ds9 and nothing looked wrong. I also checked to be sure that the psfs were spread pretty evenly over th entire image. It looks as if they are, though there's a suspicious lack of psfs in the center of the image.
I also made a histogram of the match distances spherematch is finding when I match stars between the catalogs that way. I'm suspicious of how many stars spherematch is finding--about 600 match to within 1 arcsecond out of ~30,000 stars in each catalog. Hopefully messing with match.py will shed some light on this problem.
Other than that I WCS matched the three stacks in ds9 and discovered some *gasp* wiggling in the location of stars. Incidentally, the g7 and g10 stacks appear to be the furthest off.Talked with Beth about this briefly. Doesn't seem to be a header issue because I feel that there would be a greater discrepancy, though I'll investigate this further on Monday. Also seems like the stars would be elliptical if it was a scamp issue.
The stars in the r7 stack also look a lot bigger than the others. Beth attributed this to a different FWHM than the g-band, which makes me concerned about the fact that I used the same FWHM for all my DAOphoting. But Beth doesn't think that a FWHM that was a little off should cause a big problem.
Both Beth and I seem to be out of ideas at the moment, so the weekend will be a good time to think some more. Waiting until Dave gives me info on how to give him my images via FTP so that he can offer an opinion.