The summer monsoon showed up for real two days before campaign 52 began at the Bok Telescope on Kitt Peak. Most of this first night was spent watching thunderstorms thunder down from the north. Heavy cirrus covered the sky for six hours after sunset and light rain stopped just short of the observatory. Unexpectedly, the sky became clear enough at about 0200 local time and allowed calibration standard stars and a half dozen of the brighter blazars in the sky to be observed. The seeing was highly variable and ranged from 1.3-2.5 arcsec during the final two hours of the night.
According to the forecast, the monsoon isn't going to lessen its grip
on southern Arizona for many days to come.