Re: [APML] Leonid plans

[Aplanatic@aol.com]

Matt,

Here's an approximate, but easily remembered, formula for field rotation:

http://astro.umsystem.edu/apml/ARCHIVES/APR99/msg00553.html

Considering only field rotation, for a 10 minute exposure you should try to get within about 1/2 degree of the pole.  This should be easily achieved with a polar alignment scope.  

Now consider trailing in declination for an unguided exposure.  Let's say you don't want more that 25 microns of trailing in a 10 minute exposure through a 50 mm lens.  This implies that the total dec drift must be less than 1/2000 radian (25 microns/ 50 mm).  Once again, the polar alignment error must be less than 1/2 degree to satisfy this condition.

In other words, you should be fine with bore scope alignment and unguided, 10-minute exposures.

Dave Rowe

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