[AZ-Observing] Re: Sky brightness versus aerosols

  • From: Michael Collins <cal_donley@xxxxxxx>
  • To: az-observing@xxxxxxxxxxxxx
  • Date: Fri, 10 Apr 2015 17:26:15 -0700

On 04/10/15 16:43, Brian Skiff wrote:

You'd need a lot more sample nights to test this better, but the
trend suggests the sky is very slightly brighter on nights with
higher aerosols.

I wonder how many of those aerosols are suspended high enough above
the mesa to have a direct line of sight to the millions of lights here
in the Valley. They probably wouldn't have to be very high above ground
level for that to be the case. Also, how well is the performance of a
typical SQM determined as a function of temperature? If the air
temperature was different by even a few degrees between the two nights,
it could affect the accuracy of the readings.

Anyone ever compared the readings of two or more SQMs at the same
time, to see how much variation there is from one unit to the next. I
know they claim to be calibrated, but it might be interesting to know
how precisely.

Thanks for the report, Brian. I'd have expected a bit more of a
difference than your numbers indicate.

-- Mike --
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