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Old 27-08-2009, 09:18 PM
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bojan
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Join Date: Jul 2006
Location: Mt Waverley, VIC
Posts: 7,105
The circles on your mount are for Hour angle (this one is on the shaft that is at the angle) and Declination (the shaft perpendiculat to the first one).

Declination is easy: you just have to set the Dec angle of the object, found in the catalogue.
Rectascension is trickier: you will find this number in catalogue, however what you will be setting on the circle is Hour angle - and this number must be calculated from Rectascension and Local Sideral time.
Formla is:
Hour angle = Sideral Time - RA

Local sideral time can be calculated from your geographical position and local time.
In the past this time was kept by means of accurate clock.

Last edited by bojan; 27-08-2009 at 09:29 PM.
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