[time-nuts] Sidereal time

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Jan 15 20:43:00 UTC 2010


J. Forster wrote:
> That's the point I was making earlier.
>
> Most telescopes have a FOV of at least 15 arc-minutes. You only need to
> get the guide stars into the field and go from there.
>
> Also, a telescope's pointing can be off in BOTH RA and Dec. Dec has
> nothing to do with siderial time.
>
>    
If the axes arent exactly orthogonal or the polar axis (assuming an 
equatorial mount) then the declination as measured by the telescope 
encoder is dependent on time.
> -John
>
>
>
>    
If the mount is alt-alt altazimuth etc then both axis coorrdinates are 
time dependent.

An automated telescope doesn't always have an observer available to do 
the fine pointing corrections.
Since there has been no statement about the telescope aperture or field 
of view the assumption that the FOV is 15 arc minutes or more may be 
invalid.


Bruce





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