From:  lopez@m...
Date:  Wed Oct 24, 2001  4:00 am
Subject:  Re: drift vs error

 
The following information is from the sci.astro.amateur
newsgroup:


Simply put:


For small angles a drift rate of 15.7 arc sec per
minute in declination translates to an alignment error
of one degree for both altitude and azimuth.

reference for the 15.7 constant:

from the usenet news groups:

E = (atan(b1/(15*b2))*360)/(2PI)
E = polar alignment error in arc seconds
b1 drift in arc seconds
b2 drift time in seconds

Or:

15.7 arc seconds per minute translates into an
alignment error of one degree (for alt or az).


Drift method, from many places:

First:
        figure out if hand controller is right.
        second figure out correct orientation of camera

Monitor only declination drift.
Use stars are on the celestial equator.

Star on Medidian

a. If the star drifts south, the polar axis points too far east. 
b. If the star drifts north, the polar axis points too far west. 

Star on eastern horizon (actually 6 hours offset from meridian)

a. If the star drifts south, the polar axis points too low.
b. If the star drifts north, the polar axis points too high.