Will Hakusan Creation
C14 EdgeHD, C11 EdgeHD Zhumell 8" f/6 Newt AP1200GTO, CGEM DX, CG5-ASGT Rob Miller Tri36M tripod Canon Rebel XS, Atik 314L+, DSI pro I,II, QHY5L-II SX 7 FW with Astrodon LRGB, Ha 5nm Hutech OAG5, Rainbow Optics Grating Scorpio Observatory
Quote:the sidereal tracking rate is exact in the mount (it is crystal controlled and checked here for accuracy). however, the starsdo not move at exactly the sidereal rate everywhere in the sky. the only place they move at that rate is straight overhead.As soon as you depart from that point in the sky, the stars will be moving more slowly, especially as you approach thehorizons. thus, it looks like the mount is moving slightly faster than the sidereal rate. Just because you have done a classicdrift alignment, does not mean that the stars will now be moving at the sidereal rate everywhere in the sky.in order to increase the area of sky from the zenith that will give you fairly good tracking, you will need to offset the polaraxis by a small amount. the amount will depend on what your latitude is. the other approach is to vary the tracking rate fordifferent parts of the sky. ray Gralak’s Pulse Guide will allow you to dial in an exact tracking rate for any part of the sky.
Quote:Hi all,Does anyone here know how the various mounts implement sidereal tracking?I assume the non-GoTo mounts all track at the average King rate, which is 86188 seconds per sidereal day.However, the GoTo mounts know where they are pointing in the sky, so in theory they would be able to vary their tracking rate to account for atmospheric refraction. I'm fairly sure that the Paramount does this, since it is totally reliant on its PC and pointing model, might as well do the right thing.But what about all the other GoTo mounts - Nexstar, Synscan, Gemini 1 and 2...?
Uncle Rod Uncle Rod's Astroblog: http://uncle-rods.blogspot.com/