When you are doing the azimuth adjustment, the ideal is to have the scope pointing to the intersection of the meridian and the celestial equator. In practice 10 degrees away from the meridian will work ok. Away from the equator doesn't affect accuracy, but the further away you are the slower will be the drift, so it takes longer.
For the altitude adjustment, the ideal would be a star on the horizon and on the celestial equator, but atmospheric refraction throws things off a bit, so a compromise is 20-30 degrees above the horizon and on the equator. Again, as you move away from the equator, it still works, but drift is slower.
The further you are away from the ideal positions, the more "cross talk" you get. On the meridian, almost all the drift is caused by azimuth error. As you move away from the meridian, the drift starts becoming more influenced by the altitude error as well, until on the horizon, almost all the drift is due to altitude error.
In summary, think where you have to point the scope, rather than thinking about the positions of the axes.
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Originally Posted by Dennis G
This informative artical will never date and remains a valued tool for those setting up the polar mount. I hope you are still available Geoff to answer this question. The scope in question is a LX90.
You make no mention of set up. I was of the opinion for accurate interpretation of the East or West Star's drift, the Dec pivot of the optic tube must be vertical and remain so while observing the star's drift and the scope must be tracking - driven. For the meridian drift the Dec pivot must be horizontal and the scope travcking while the observation is made. Your comments Geoff would be appreciated.
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