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Old 16-09-2009, 12:57 PM
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mtodman (Matt)
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Join Date: Oct 2007
Location: Arcadia, NSW, Australia
Posts: 191
Polar misalignment - Maximum exposure times

OK, I've come to the end of my tether with trying to guide out the dec drift on my equatorially (wedge) mounted LX200GPS. I have permanently mounted my scope on a pier and have now achieved very good polar alignment (after much fiddling). I'm getting no noticable drift in 5 minute subs with Dec guiding turned off. The problem is that I am now very reluctant to remove my scope from the pier as I would need to go through the reallignment procudeure again.
I therefore have the following question.
Assuming that I only guide in RA, is there a way for me to work out the maximum single exposure duration I could achieve for a given polar misallignment before I notice elongated stars due to a drift in DEC? I assume a number of variables would come into play?
Polar misallignment amout
Focal Length
Imaging resolution (arc secs per pixel)
RA Position of object

Is there some lovely equation or software out there that can help me out?

Cheers
Matt

Last edited by mtodman; 16-09-2009 at 01:10 PM.
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