![]() Once a field of view away from the equator is chosen, drift in that field is sensitive to both degrees of freedom of polar misalignment and one can think about polar alignment without moving between fields. The fact that no drift of the stars in a field near that axis of rotation will be seen is what requires a second equatorial field to align the polar axis. While most S&T readers understand this well, what may not so well known is that from the perspective of a tracking OTA with some polar-axis misalignment, the celestial sphere is rotating about an axis through the equator determined by the polar-axis orientation. MacRobert's article outlines the drift method for polar alignment as it is universally quoted, where the drifts of stars in two equatorial fields are used to determine the direction towards which to move the polar axis to better align the it with the celestial pole. ![]() When followed, you will end up with accurate polar alignment to help your astrophotography - enjoy! ![]() If you're in the Earth's Southern Hemisphere, reverse the words "north" and "south." If your eastern sky is blocked, you can use a star low in the west and reverse the words "too high" and "too low" in the above instructions. When all visible drift is eliminated the telescope is very accurately aligned, and you can take long deep-sky exposures.
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