Extraordinary night – followed the Moon from moonrise until dawn. Clearest night we have had yet. Halo almost non-existent on DS.
This shows that we may be able to get very good data very close to the Sun – but in that case extreme refraction would have to be handled. Will look into whether this can be achieved from the JPL ephemeris. Exposure time also needs to compensate for the strong extinction through 5-10 airmasses. Not sure how to do that without stopping and starting scripts.
Brilliant! That’s really great news — we can measure the extinction from this night and compare to nights when the halo was broader. Also, it might be possible to track alpha in the halo as a function of airmass — we haven’t tried that yet!