The lab was in a bio lab, so the AC was set to STP. Well, mostly. Just having a warm person breathing in the tiny room was enough to throw the mirrors off. Sinc

The lab was in a bio lab, so the AC was set to STP. Well, mostly. Just having a warm person breathing in the tiny room was enough to throw the mirrors off. Since we were doing active tuning and development on the optics, we had to be in there, and it took a bit to get the room to a steady state with us in it. Fortunately, during the summer or winter, the only thing what would change was humidity, not the temperature, and that seemed to not affect things too much. Also, not a stupid question. We thought of it too and it took us a week to collect enough data to rule out the AC system as a cause.