Quote:
Originally Posted by rat156
Hi Greg,
You can always tell the nights of good seeing. The auto guider image doesn't jump about all over the place. I usually sit at the computer watching the guide errors to estimate the seeing. If they rarely go above 0.5, it's the best seeing I can remember, probably only happened once or twice, sometimes the maximum guide errors are about 1, but usually they go out to 1.5, which means I have about 3" p-p, what I expect from suburban Melbourne.
Cheers
Stuart
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Yes I do the same. I like to see the guide errors before I walk away and let the scope do its thing. It varies with setups but at about 1260mm focal length at my dark site I would see errors of about .1 to .9 with about .3 being the average. Sometimes it is lower and that would be seeing. You see it in the images though quite easily at long focal length. On bad seeing nights I can't even focus my CDK17 as one image can seem in focus the next with no change is out of focus.
1.5 errors would be too high on my setups and locations. When it starts averaging 1 its getting a bit rough and .4 to .5 is usual for the CDK at 3 metres on a PME (which seems a bit better than the PMX - not much but about 25% better) and .3 average for the TEC180. AP140 widerfield is usually around .25 average guide error on a PMX.
Paul, that is a very valuable location you've got there. What sort of percentage of nights are clouded out?
My dark site has a fairly high percentage of clear nights but occassionally plagued with wind of around 20kts. That's ok for a small refractor but not anything else.
Greg.