From: Milton Aupperle <milton@outcastsoft.com>
Date: January 10, 2007 12:17:18 PM MST
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Re: New Luna Images
Hi Tim;
The place I was imaging from (Misstussine 1000 feet ASL) was right beside a frozen 300 mile long dammed lake. However the north end where the spillway feeds into the south saskatchewan river is always has open water, so their was a lot of humidity too. In Calgary we are at 3,300 feet ASL and with typically zero humidity so this is rarely a problem.
What worked for me was to wrap the C8 tube with an electric blanket and set it on high. That kept the frost off both the corrector plate and the mirror too. I normally use the blanket with the Laptop to keep the LCD from freezing solid, but it wasn't quite cold enough for that to happen this time. It's too bad that I didn't find this solution earlier on, as I was imaging M37 (very photogenic colorful star cluster) and the horse head in Orion and the corrector plate was 2/3's opaque and the main mirror was white. M37 wound up with a soft glow around the stars, which is sort of a nice effect visually.
The HEQ5 mount got cranky once it dropped below -10°C and then the RA drive would bind, so I only got 15 minutes worth of exposures on the horse head (if you push the image processing a lot, you can make it out). So I hauled the mount inside, let it thaw out and then removed the black gunk that Synta calls "grease" on the RA and Dec worm gears. Even with WD40 it was a PITA to get it off and I had to use a tooth pick to clean out the gear gaps. Greasing with Lithium made a big difference and it moves a lot smoother. However I still had some binding issues because I had the set screws for the worm gear in too tight and they had to be adjusted for temperature too. For example at +5°C their was no binding, but at -20°C it was sporadically binding due to contraction of the metal parts. And fiddling around with a flashlight, a screwdriver and two allen wrenches at -20°C just is not as much fun as it used to be.
But it's all sorted out now and I'll give it a definitive test when it drops down to around -30°C here on tomorrow.
TTYL..
Milton J. Aupperle
President
ASC - Aupperle Services and Contracting
Mac Software (Drivers, Components and Application) Specialist
#1005 - 815 14th Avenue. S.W.
Calgary Alberta Canada T2R0N5
1-(403)-229-9456
www.outcastsoft.com
On 10-Jan-07, at 11:48 AM, Tim wrote:
Milton:
I like the results you're getting with the color flea2! (especially
since I now have one).
I noticed your remark about ice crystals on the corrector. I have
this problem with my C-8 as well, for which I don't have a dew
remover (like I do for the 9.25", but that's not currently mobile).
When I was in Utah in October, I had 5 nights at about 20° F. The
first night was the most humid (high desert at around 5000ft, usually
dry), and I was trying long exposures with various cameras. I slept
during the exposures, and when I went out to put the equipment away,
the corrector on the C-8 and the objectives on the Jaegers 6" and
Megrez 80 were completely opaque there was so much ice on them. I put
them in the spare bedroom in the house without the covers on, so they
could defrost and dry.
At home, when I'm using the C-8 in humid conditions, I actually use a
heat gun to remove the dew, being very careful to keep it moving and
hold it a foot or more away from the corrector.
-Tim.
--- In Astro_IIDC@yahoogroups.com, "Milton Aupperle" <milton@...> wrote:
Hi Folks;
Despite some issues with my HEQ5 mount (it really doesn not like -20°
Centigrade weather), I still managed to get a little bit of imaging in
over X-Mas.
Here is the 15 day old moon and a detailed strip along the western limb.
http://groups.yahoo.com/group/Astro_IIDC/files/Lunar/20070104_MJA_Luna.jpg
It's scaled down by 50% from the original and was shot using a color
Flea2 1032x776 camera with a Focal Reducer on the C8 (1000 mm focal
length). Seeing was about 5 to 6 / 10 turbulence, but I had 50 to 70
km surface winds blowing the mount around. It's a composite of 14
movies for the full disk and the details strip is another 9 movies.
Exposure times were 3 ms per frames, so you can pretty well freeze out
any turbulence.
And here are the normal and enhanced color images of the 7 day old
moon at:
http://groups.yahoo.com/group/Astro_IIDC/files/Lunar/20061227_MJA_Luna.jpg
I also managed to capture the Valentine Dome then too.
TTYL..
Milton Aupperle
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