Bob,

I don't know them probably because I haven't been in precision Photometry circles. But I'm always willing to learn from an expert!

I'll have a data set tomorrow that for a few filters I was able to get constant exposure time flats with all frames within target illumination by +-15% (see my notes above on how I "tricked" the script into getting these). This should allow me to calibrate the flats correctly and minimize the residual pattern noise that the flats are carrying into my light frames. I'll let you know how that works out.