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Originally Posted by sejanus
i thought I'd make a new thread rather than cluttering my old one.
1) point mount exactly dead south according to magnetic compass
cheers
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As the wise Mr. H0ughy said; you actually want the polar axis pointing to the “geographic” South Celestial Pole (SCP) rather than the “magnetic” S Pole. The SCP is the point on the imaginary celestial sphere around which the stars appear to revolve. It essentially defines the axis of rotation of the Earth as it spins on its axis once every 24 hours.
This “geographic” axis of rotation and the “magnetic” axis defined by a compass do not line up, and their offset varies quite markedly world wide. For me in Brisbane, when the magnetic compass is pointing to magnetic South, the "true" SCP, or axis of rotation, lies 11 degrees to the East.
Just another trap for newcomers to the black art of polar alignment...
Cheers
Dennis
Edit: ...and the wise Mr. Sheeny, I didn't see his very nice explanation before posting...