FreeLists / az-observing / [AZ-Observing] SQM Data Plots for Hour of Darkness

[Tom Polakis <tpolakis@xxxxxxx>]

While I was at the Science Center, I pointed my Sky Quality Meter at the 
zenith, and took three readings every 10 minutes.  I walked a couple hundred 
feet from the well-lit star party to a small rise.  The data is plotted here.

http://members.cox.net/tpolakis/astro/sqm_phx_20080329.jpg

The two plots are the same, but the latter plot has an expanded scale that 
shows how much any perceived trends are overwhelmed by scatter.  Not much to 
say, other than that there was no measurable reduction in sky brightness during 
that hour.  Also, it is apparent that twilight was interfering right up to the 
hour in which the lights are supposed to be turned off.  In other words, the 
hour begins too early.  The only ways to get good sky brightness data before 
and after  the hour of darkness would be to either move it to 9-10 p.m. or have 
it closer to the Winter solstice at 8-9 p.m.  Since the Earth hour does not 
revolve around our brightness measurements, I don't see either of these changes 
happening.

Since the Science Center proved incapable of turning off the terribly designed 
lights in the immediate vicinity, even the star party participants were 
deprived of any advantage during the hour of darkness.  The most striking 
difference was the tall buildings such as the nearby Sheraton and APS buildings 
with all of their lights off.  It reminded me of the skyline of Detroit that is 
showcased over the center field wall at Comerica Park, with the difference 
being that the Phoenix buildings are not vacant.

Tom
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