higher than that

Joe wondered about adding a Sky Quality Meter to the new weather station equipment at the David Dunlap Observatory so to monitor trends.

Paul replied and pointed out the Unihedron units are pretty expensive. He also noted that periodic measurements had been taken. "We already know that a clear dark moonless night around Richmond Hill is 18.3 mag/arcsec²." He suggested downtown Toronto would be 17.0 or worse. Kitt Peak is 21.8. He wondered out loud what the CAO number might be, guessing 20.0 or better.

I checked my notes. The best I had ever seen was 21.20 in late Sep, last year. And in July 2010, had hit 21.16.

§

Stu reported that they reached as dark as 20.9 at Long Sault. But the last time was 20.5.