Re: [Utah-astronomy] SPOC informal member party 20090320 ZLM 5.6
Kurt: I thought the night was pretty good for the season of the year. Anytime you can get mostly clear on a moonless Friday night with no frost you sort of have to do something about it. The cool people at the west end were afflicted with mosquitoes and dated humor from last century. But it was good to be out with friends again. DT --- On Sat, 3/21/09, Canopus56 <canopus56@yahoo.com> wrote:
From: Canopus56 <canopus56@yahoo.com> Subject: Re: [Utah-astronomy] SPOC informal member party 20090320 ZLM 5.6 To: "Utah Astronomy List Serv" <utah-astronomy@mailman.xmission.com> Date: Saturday, March 21, 2009, 2:57 PM
Jay,
The SQM has a precision of 0.1 mags, and the underlying documentation on the NinePlanets TLM charts (after McBeath) have a precision around 0.3 to 0.4 mags. So there is enough overlap from my SQM reading to get within your range of 5.7 to 6.3. TLM at SPOC is variable by the time of year. It is sensitive to atmospheric moisture, which is higher in the spring. More moisture reflects more light pollution from the ground.
It may have been a measurement error on my part. I was closer to the east end of the SPOC lot. There is a line of poorly shielded street lights about 1/4 mile south of the property that may have bled into the meter. Maybe I'm misremembering, but these street lights seem to be new and in any event could be corrected with a minor shield addition. The SQM TLM reading might have been better if I went into the "dark hole" at the west end of the lot where all the cool guys hang out. But they wouldn't let me back there. -:)
I usually just like to post the TLM reading should anyone desire to argue with their astronomy buddies about what DSO's were visible and which weren't.
Even so, the main show was that a good time was had by all. March and April are usually pretty iffy in Utah, with high winds aloft creating alot of sucker nights. By the time you set up, a high cloud layer has blown in - seemingly out of nowhere. So, I was happy to get in at least one March night in with good seeing and transparency. May be one of the few that we get over the next couple of weeks.
- Kurt
P.S. -
My website on TLM measuring - http://members.csolutions.net/fisherka/astronote/plan/tlmnelm/LimitMagFields...
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com
Kurt, I will echo Daniel's comment that it was a pretty good night for SPOC at the spring equinox. My admittedly non-scientific impression is that the sky was noticeably darker to the west and southwest (as it usually is), which may explain why M42 was so outstanding that night. I'm assuming your measurement was for the zenith? Even looking at the winter Milky Way, that part of the sky still seemed darker than other regions. And the transparency was exceptional. Even when the breeze picked up about 10:30, the seeing only degraded marginally. I wish I could have stayed longer, but family obligations prevented me. Still, a few hours is better than nothing. My astronomical juices are flowing again, like sap in the trees. On Sun, Mar 22, 2009 at 2:45 AM, daniel turner <outwest112@yahoo.com> wrote:
Kurt:
I thought the night was pretty good for the season of the year. Anytime you can get mostly clear on a moonless Friday night with no frost you sort of have to do something about it. The cool people at the west end were afflicted with mosquitoes and dated humor from last century. But it was good to be out with friends again.
participants (2)
-
Chuck Hards -
daniel turner