Hello Les,
I use AIJ without problems for polarimetry mostly, but have also used for photometry also without problems with an earlier version of the BAA spreadsheet. Can’t claim to be an expert though, but can try to help. Just wondering why your measurement file has ALT_OBJ as NaN but AIRMASS OK, presume your use of DP Coordinate Converter and call to SIMBAD was OK. You can specify that ALT_OBJ should be decimal in aperture settings keyword tab in AIJ – perhaps check it’s there in the header (apologies if you’ve tried all of these already). I don’t know if the presence of NaN anywhere in the data would be enough to cause a problem in BAA spreadsheet even if that piece of data unused. Anyway, my email john-dot-jean-dot-simpson-at-gmail-dot-com.
john s