Taken through a luminance filter only, with zeropoint from UCAC4 R mags, the SN comes out around R = 14.4
The timestamp is slightly wrong. I leave Astrometrica to take the start of exposures from individual FITS for track and stack (which is correct). It won’t automatically read the midpoint value put in the header by Maxim when I do a prior stack in that software. Of course I could input the midpoint manually into Astrometrica using the image parameters menu…