The Lights of Flagstaff

It is Sunday morning, and our first night on the 72-inch is tonight.  The 72-inch Perkins Telescope is located at Lowell's Anderson Mesa Observing Station, about 12 miles south of Flagstaff.  It was established in 1959 as the observatory's dark sky site away from the lights of town.

Even though Flagstaff has 58,000 people, it is as dark as they come for a town of that size.  This is because over the years, it has established aggressive light pollution ordinances.  In 1958, Flagstaff passed what is believed to be the first light-pollution legislation in America. This ordinance prohibited "the use of certain commercial searchlights within the city limits" with a misdemeanor fine of $300 or "imprisonment in the City Jail not to exceed 90 days."

A lighting code was adopted in 1989 establishing dark zones. It was updated in 1992 and 1999. A sign code adopted in 1997 now manages commercial sign design and that mandates light lettering on dark backgrounds instead of the typical dark lettering on bright panels. 

Ralph Megna and I visited Flagstaff last year and were struck by how dark it seemed in the main street in town.  Of course, our eyes were not dark adapted.  Still, it was quite an achievement.  Last night I walked to the Barnes and Noble and took a brightness reading with my Sky Quality meter from a dark corner of their parking lot.  I got a reading of 19.05 magnitudes per square arcsecond with a 4 day old moon in the sky.  As a comparison, my backyard in Rancho Cucamonga normally measures around 18.0 to 18.3 magnitudes.  GMARS will typically be around 21.3 on a moonless night.  I will get a reading from Anderson Mesa later this week.

Flagstaff in a picture taken from Mars Hill in June 2003.  Route 66 crosses town just to the left of center.