Tonight was a classic example of why a moonless sky can be the difference between a useless night and a surprisingly productive night for spectropolarimetry. The sky was a complete mess with varying amounts of cirrus plus mid-level clouds, both products of monsoon storms that fired up during the afternoon just south of the international border. Even with the ample clouds shown on the satellite image, amazing opportunities presented themselves and a good number of targets were successfully observed. This would have been impossible with a bright moon in the sky. After midnight, conditions improved a bit and even a little differential photometry was attempted. The seeing was excellent throughout, usually hovering around 1 arcsec.
Although it is impossible to truly predict what the monsoon will do from day to day, the forecast has much wetter and stormy conditions hitting southeast Arizona starting tomorrow and lasting through to the end of the campaign. However, tonight and the previous night insure that the campaign isn't total bust.