Quote:Ok, here is where I think I'm confused. I was always under the impression that Dec drift is always due to polar alignment error and RA drift was always due to tracking accuracy. After some investigation I'm thinking that RA drift can be due to polar alignment error too. Roland stated this in an email recently but I just couldn't get my head around it or past my previous assumptions. He said that RA drift was due to altitude error.So it could be my polar alignment that is off. With some clear skies I may be able to test this theory. Perhaps sometime in October. The good news is that my AP900 mount was then showing dramatically good tracking! 3 arc seconds peak to peak is remarkable without PEC on.
Uncle Rod Uncle Rod's Astroblog: http://uncle-rods.blogspot.com/
"Don't sweat the petty things and don't pet the sweaty things" - George Carlin deanrowe.net/astro Whats with that avatar?