All night long there were clouds to the north and clouds to the south.
Later in the night, there was even some lightning to the west(!). Somehow,
Kitt Peak stayed in a clear spot the whole night, except for widespread
the start and a few isolated patches of cirrus passing through that didn't
significantly affect observing.
It was a very dynamic night in terms of seeing, which was very poor (2-4
arcsec) right after evening twilight.
The rest of the night was much better, with
the seeing being around 1-1.5 arcsec most of the time. There were some odd
periods, however, when the seeing degraded to over 2 arcsec.
The instrument problem that cropped up last night appears to be
resolved and it turned into a nice, productive night.