Re: [APML] Polar Alignment -- 0 or +10 degrees

[Chris1011@aol.com]

In a message dated 10/14/2002 11:14:15 AM Central Daylight Time, gwhitney@maine.rr.com writes:


> Just a detail of clarification needed:
> When one polar aligns via the drift method, does one choose a star on the
> Meridian at "0" degrees or "+10" degrees and why?  And as a follow up, is
> the optimal declination for the eastern star also the same?  I am interested
> in finding out the why behind the correct answer.  Many thanks.
> George


I would not do a drift alignment with a star in the east. Doing so will not achieve optimum drift because of atmospheric refraction effects. Now that CCDs are the primary imaging tool, very small amounts of RA and Dec drift are glaringly obvious. It is quite easy to eliminate drift in these two axes using the power of the CCD. Adjust the altitude and azimuth axes using a star near the zenith. I have found that the Track&Accumulate graph in CCDOPS is the quickest and most accurate way to zero in on drift. The graph tells you within a few minutes the amount and direction of drift in both axes, and you will be able to make adjustments to the mount quite easily. 

Roland Christen