From: Mark Gaffney <markgaffney@me.com>

Date: December 8, 2009 5:53:36 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] cold weather..


Hi Milton, 

I`ve got a lemonade & some ice-blocks here now! Talk about two different extremes of weather at different parts of the globe! Your Crab Nebula looks a little better than the previous one with the Grasshopper! (although I don`t have them here to compare side to side). Thanks for the details of exposures. They`re beginning to make more sense to me due to a little more experience (though not really practical) with these things. I`m ordering an Atik FIRA 1 filter wheel on Christmas eve but it`ll be a while before I can get the Astrodon`s. With a bit of luck I`ll be able to take some B/W shots of one DSO or another this summer. It`d be nice to get some results of the moon to compare favourably with Howard`s using the Scorpion though. He seems to be the yard-stick..i.e. the other person posting moon images on the group with this camera. I can`t work out whether I`ve got some setting wrong but my fine focus whilst OK with the Flea 2 is lacking with the Scorpion...


Mark.

On 09/12/2009, at 9:49 AM, Milton Aupperle wrote:

Hi Mark;


Nope never heard of them before. Thanks for the link.


On a related "extreme weather" topic, I managed to capture a fairly decent  image  of the "Cold Crab" M1 last night despite the frigid well below normal temperatures.


http://groups.yahoo.com/group/Astro_IIDC/files/DSO/ColdCrab_M1_LRGB_20091207_MJA.jpg 


I shot eight 12 minute Luma and then turned on Binning 2x2 to shot the RGB color channels as five frame each of R 5, G 3 and B 2 minutes exposures. This is on the C8 at 1150 mm focal length and I had the Grasshopper EXHAD camera cooled to -45°C. Applied darks (including synthetic darks), flats, stacked it and then did some image processing in Astro IIDC.


I think some of the color cast issues are due to frost / ice on the CCD, as the corrector plate had some frost on it at 2:30 am when I finished up and the CCD in the camera was 20°C colder than that. I probably should not have cooled the camera at all.


It was -28°C outside (that's 14°C below normal temps) and the air had moderate ice crystals which added haze and raised the sky background light pollution substantially, even with the Hutech IDAS LPR in place. The slightest breeze drove the temp down well below -35°C. The firewire cables were like solid rods and caused some tracking issues because they wouldn't flex as the mount moves, so I need to rethink my cable management set up. The GPUSB and Keyspan RJ12 cables were like fragile little pieces of balsa wood, stiff and ready to snap. I had a heating pad under the laptop and both of them inside a clear plastic bag to keep the heat in, which worked well as the laptop hard drive didn't freeze solid like last year, but it makes it awkward to use for focus and capture. I wrapped another heating pad around the mounts main axis, gearing and motors which worked well at eliminating binding of the HEQ5 mount with these large temperature swings. It basically can not handle more than about 15°C swing in temperatures without needing to be re-tuned, which means removing the front electronics plate screws, then loosening the 3 bottom hex bolts and then with another allan key, loosen or tighten the worm positioning bolts, all barehanded. If you live in a cold climate, don't buy a Synta HEQ5 / HEQ6 (or Sirius/ Atlas mount) or your just asking for heart ache.


One nice thing about temperatures below -25°C is you get virtually no mirror flop on the C8, as the focus knob is so stiff and slow to turn that it barely moves. I imaged M45 first then swung over to M1 and no shift in the image or change in focus.


TTYL..


Milton Aupperle



On 8-Dec-09, at 2:17 PM, Mark Gaffney wrote:



Hi Milton, were you aware of this group, 


Mark..

http://tech.groups.yahoo.com/group/extremeastronomy/