10:48. And shaking. Tried to split Porrima. It can be done at 217x but it's not great. The split is clear at 391x but the seeing is really bad so everything jumping around.
Tempted to try measuring it with Geoff's eyepiece. What the heck! I'm gonna pop it in...
11:03. I think the split is about one-half or one-third of a single tick (without a doubler). I'll calculate that later. By the way, the Celestron Micro Guide eyepiece is 12.5mm (yielding just over 300x).
It's tough to say for certain. In addition to the seeing conditions, the wind is shaking the 'scope. The 10 Minute Average Wind Speed is 20.9 km/h. The Davis Instruments weather station shows a high of 32.2.
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The linear scale divisions are approximately 5.3 arc-seconds (in the C14). So the separation is approx. 2.6" to 1.8". This seems inconsistent with estimates in wikipedia... But Eric said in his The Sky This Month May presentation that they were 1.25" apart.
Hmm. If I divide by 4, I get a separation of 1.32!
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I wonder if, with extremely tight doubles, it would be worth increasing the magnification even more, say with a Barlow. Then, the apparent image would be larger. Instead of having stars between the tick marks, you'd have them spanning several.
Friday, June 05, 2009
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