[AZ-Observing] Re: [hac] Sky Brightness Update for metro Sierra Vista area
- From: "Wayne (aka Mr. Galaxy)" <mrgalaxy@xxxxxxxx>
- To: haclist@xxxxxxxxxxxxxxx
- Date: Thu, 24 Mar 2011 16:43:11 GMT
Benson, AZ 85602
hm ph: 520-586-2244 I had a pleasant night here until moonrise. Seeing was much
better than it has been lately. I was able to resolve quite readily the double
star alpha Comae Berenices (about 0.6 arcsec separation) with my 13-inch
reflector at about 500x. I also scanned around the Virgo Cluster of Galaxies
and saw nearly 100 galaxies in the area. The transparency was surprisingly good
since smoke from the Duke Fire was blowing this way. I could see down to about
magnitude 6.5 according to the Globe at Night charts of Leo. Clear skies,
Wayne (aka Mr. Galaxy)
---------- Original Message ----------
From: "Doug Snyder" <starhaven@xxxxxxxxxxxxx>
To: <haclist@xxxxxxxxxxxxxxx>
Subject: Re: [hac] Sky Brightness Update for metro Sierra Vista area
Date: Thu, 24 Mar 2011 08:28:52 -0700
Hi Mike, Thanks for the input and I kind of agree with you about the degree of
darkness those readings show and that it does appear to get 'darker' after
midnight (in some areas). It's just that the moon rose about 11:30 pm last
night, so I wanted to get the readings well before then. So I am inclined to
think that there is somewhat of a variability beteen time of night, season, and
of course changing sky transparency due to wind, humidity, larger area fires,
etc. A couple of us will be getting additional SQM readings this saturday
night over at Kartchner Caverns during the 'star night' there, and you're most
welcome to come on over and have some views - heck, we'll even be able to bask
in, well, at least view, the Tucson sky glow. I'll see that Don Brush gets a
copy of that email. Thanks. Doug ----- Original Message -----From: Mike
ShadeTo: haclist@xxxxxxxxxxxxxxxxxxx: Thursday, March 24, 2011 7:06 AMSubject:
RE: [hac] Sky Brightness Update for metro Sierra Vista area I am a little
surprised by some of the readings showing it being as dark as it is. I think
that Don Brush may be interested in seeing these�although I think it
would be interesting to see them replicated later at night or early morning.
My subjective experience suggests that the sky in Sonoita gets darker after
about midnight, especially towards the east (Sierra Vista area). The biggest
issue seems to be the fort. Wonder if it would be possible to correlate these
results with other variables such as season, time of night, and so on. Would
also be interesting to see them for the Tucson area.
From: haclist@xxxxxxxxxxxxxxx [mailto:haclist@xxxxxxxxxxxxxxx] On Behalf Of
Doug Snyder
Sent: Thursday, March 24, 2011 12:05 AM
To: haclist
Subject: [hac] Sky Brightness Update for metro Sierra Vista area
To HAC List readers, contributors, and lurkers,
Jean and I just returned from a two-hour, 48 mile round trip, sky brightness
measurement 'tour' of ten locations located between our Palominas Observatory
and Sierra Vista City Hall (near Coronado and Hwy. 90 Bypass). This tour was
conducted on March 23, 2011 beginning at 2000 hrs MST (8 pm) and completed at
2200 hrs (10pm) on the same date. The sky conditions were excellent - No moon
present, zero clouds, slight breeze, excellent transparency, and astronomical
twilight began at around 1955 hrs (7:55 pm). This same 'tour' was conducted
two years and five months ago on October 21, 2008, using the same sky
brightness meter from Unihedron (an 'L' version). The readings from the sky
brightness meter are in magnitudes per arcsecond squared (search Google for
explanation!) The same ten locations were measured during both tours, and I
include below the readings taken on each of the two 'tours'. For the HAC
people in Cochise County, I show the 10 locations as road/street/landmark
names, but for any possible future GLOBE AT NIGHT submittals, I will include
the lat./long. coordinates taken from Google Earth.
For darkness examples, a reading of 22 on the meter would be very dark sky, and
a reading of 17 would be a quite bright sky. For the readings shown, all
attempts were made, as much as possible, to avoid being close to near-by
lights, and also avoiding any parking lot lights, and traffic!.
The readings below consist of location number, roads or landmark, time of the
2011 reading (MST), Sky Brightness Reading (The mean of three readings), and
any of my comments. The first reading is what was measured in 2008, and the
second is the reading for 2011.
1. Palominas Observatory, 2000hrs., 21.15 (2008), 21.20 (2011)
2. Palominas Rd./Hereford Rd., 2019hrs., 21.23, 21.25
3. Moson Rd./Hereford Rd., 2027hrs., 21.14, 21.15
4. Madera Dr./Arabian Rd., 2036hrs., 21.03, 21.00, Near Junk Bond Observatory -
site of past HAC public star parties
5. Ramsey Rd./Hwy. 92, 2045hrs., 20.80, 20.75, A traffic signal and a few
street lights now exist - were not there in 2008
6. Hwy. 92/Glenn Rd. 2051hrs., 20.30, 20.35, Sierra Vista city boundary
7. Hwy. 92/Buffalo Soldier Trail (SE), 2056hrs., 20.22, 20.15
8. Avenida Cochise/ Hwy. 92 (NE), 2103hrs., 17.50, 17.90, The Mall At Sierra
Vista - NE lot, just north of Dillards
9. Veteran's Memorial Park, 2114hrs., 19.00, 18.65, Soft ball field next to new
city skate park; lights were on at skate park; former location of HAC event
10. Sierra Vista City Hall (Coronado/ Tacoma), 2120hrs., 18.20, 17.25, many
more buildings, ongoing construction and lights now in this area
1. Repeat measurement upon return to Palominas Observatory, 2200hrs., 21.35,
21.30, the difference from 2000hrs. reading due to sky rotation
Perhaps the 'surprising' readings were taken at the Mall (location 8); even
though showing an 'improvement' from 2008, the variability of the lighting
in the mall complex is significant and it is certainly not to be
considered a 'dark sky site'.
I'll continue to observe from my Palominas location for a while longer.
Your comments or questions can be entertained (or equally ignored).
Clear, Dark Skies,
Doug Snyder
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