Expirements at COE

Greg Claytor

I enjoyed Saturday night with TACos and SJAAers atop the hills of Coe where I embarked on spider experimentation, testing my new robot eye and engaging in another one of my favorite astro tasks. socializing.

The night began well before sunset parked between Laflamme and Baker. We kibitzed as I cut out an aperture mask for the Zeiderscope. I managed to turn a 17" newt into a quasi 6.5" refractor. The point of this exercise was to test the different diffraction spikes generated by 3 and 4 straight vane spiders and 4 vane curved vane spiders. I have a few choices to make in order to complete the 16" scope I'm working on and thought this might help lead to some conclusions.

I used hack saw blades for the straight spider and 1/8 inch solder for the curved compliments of our own Grande Fromage of Plumbing, Mr. LaFlamme. What we discovered has already been well documented; however, to recap: 4 vanes produce four spikes. 3 vanes produce six spikes yet shorter than those of a 4. Doubling the thickness of the spiders does in fact extend the length and brightness of the diffraction spikes. The surprise came from the 1/8 thick curved solder spider. The spikes completely disappeared. We later straightened out the solder, laid them out across the mask and the spikes were the brightest we viewed, so curved vanes definitely diffuse scattered light. With only 6.5" of aperture it was hard to observe increased background brightness.

My rebuilt left eye was the next test subject. The first thing I noticed was that it took some precision to line up my new eye with the eyepiece. If you've ever held your eye away from an eyepiece and watched as the small cone of visible light move about the top of the lens and tried to center your vision on that target, then this is similar to what I observed; however, my eye was against the rubber eyegaurd. Next, I noticed that my lens adds a bluish tint whereas my natural eye adds gold or yellow. I was happy with the contrast though. Lights were bright and blacks were black. I tested the sharpness difference on Saturn. The banding was hands down more apparent with a natural eye. The sharpness was similar, but the detail was harder to see with the rebuilt eye. It almost seemed too bright. I'd like to try this again using some filters. My goal here is to note what it might take to get the rebuilt eye as close to my natural eye as possible that way when the day comes to replace the good eye I'll already have things figured out.

The rest of the evening was spent checking out different scopes, equipment and objects. I started with the differences between Argo Navis and Sky Commander. Thanks Greg L, Dan K and Michael Schwartz for walking me through the menus and allowing me to navigate them. In the end I favor the Argo Navis for the simple reason that I can see it better in the dark. Michael's Plettstone is magnificent. Got some ideas. Scott baker was imaging with his TeleVue, Dan was picking off objects left and right. I don't think Scott likes anything brighter than mag 12 in his little 10" dob. My buddy Chris showed up and was picking off his list of gotta sees as was Greg LaFlamme. There was considerable chatter about "The Wanderer", what it was, etc. Mark Johnson switched from Bonny Doon to Coe at the last minute. It was nice to him again as well.

See you TACos next time out.