[time-nuts] Sidereal time

Magnus Danielson magnus at rubidium.dyndns.org
Sat Jan 16 03:23:56 UTC 2010

Hej Bruce,

Bruce Griffiths wrote:
> Hej Magnus
> No one bothers with such gear ratios for a modern telescope as its 
> cheaper to use a computer than have a set of custom gears made.
> In any case, direct drive of the axes is sometimes used - no gears:
> http://www.halfmann-teleskoptechnik.com/e_index.htm
> Calculating the time is just the beginning if you want to point to 
> Saturn for which the RA and DEC vary over time and the simple model 
> isn't very accurate:
> http://ssd.jpl.nasa.gov/horizons.cgi

I was meaning mathematical gears, not mechanical gears.

The simplified approach was just to present an alternative for those in 
need of a little less precission as their scopes and associated pointing 
needs is a little less than the large scopes. Just as an idea. The main 
idea was that the open-loop calculations could be simplified if a 
calibration would create a closed-loop for the offset part and remaining 
open-loop errors would be relative negligable for the application.


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