I agree, its worth checking. I’m using AiJ for processing and as far as I can see it assumes its being given start of observation times in the DATE-OBS field coming from the capture software. I couldn’t find a way of changing that assumption in AiJ so to get the times right I had to edit the output files. If I use SIPS I don’t have to do this. For many this probably doesn’t matter much but I’m timing the minima of eclipsing binaries so if the timings of the observations are wrong, the minima will be wrong too. I can see it’s also important in astrometry.