[g__day (Matthew)]

This is a question for anyone who has really tried to nail polar alignment on a permanent mount using an SCT - which is exposed to some degree of mirror movement that can confuse the accuracy of your alignment corrections.

I tracked Rigel Kentaurus for about three hours last Saturday - the star was about 1.5 arc minutes off target. Now normally one could do the maths and say well I'm an arc minute off in DEC, but with an SCT life isn't so easy. I went slightly squirrelly earlier this year trying to use PEMPro's polar alignment wizard to nail polar alignment - until I discovered mirror movement was confounding ultra precise alignment.

I switched to a side mounted MAK OTA and got polar alignment much more precise. So now whenever I see drift I wonder how much of it is real and how much is gear or mirror movement?

I have in the past tried MaxPoint to model my pointing parameters - out to 100 stars. My assumption is any mirror shift is consistent all across the sky (a dubious simplifying call).

How do other folk account for this challenge (other than locking your primary mirror in place)? Does Tpoint handle this challenge alot better than MaxPoint anyone?

Many thanks,

Matt