Rapidly decaying late-afternoon thunderstorm clouds prevented the start
of observations until the end of evening twilight and cirrus prevented
photometry during the first hour or so of the night. After that, the sky
was generally clear and the seeing ranged from 1.0-1.6 arcsec. In the
last hour of the night, the humidity rose dramatically close to the dome-closing
limit and mid-level clouds started moving in from the east. Observations
of the last target
continued until mid twilight through clouds.