Re: [APML] Declination drift error quantified?

[Aplanatic@aol.com]

This one is really simple.  The apparent declination of a star, as seen by the misaligned scope, is sinusoidal with a period of one day and has an amplitude equal to the misalignment.  In mathematical terms:

delta_declination = A*sin(2*pi*t/1440 + theta)

where t is in minutes of time, A is the polar misalignment in degrees and delta_declination is the apparent declination error as seen by the scope in degrees.  Theta is just some phase angle that depends on the scope's pointing direction and the direction of polar misalignment.

The rate of declination drift is the derivative of the above, and has a maximum of:

dec_drift_rate(max) = (2*pi/1440)A

where dec_drift_rate is in degrees/minute of time.

So, for a one degree error in alignment, the worst case drift rate is 15.7 arcseconds/minute.

Dave Rowe





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