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Originally Posted by g__day
WoW!
So the Sun (and presumeably all Star's) arcs do change significantly over the sesaons by the above post - but the SCP doesn't alter - its that the answer to this apparent conumdrum?
The pier is dead level on the mounting plate - both by a spirit level and the GE mount's bubble - so any error is my procedural fault I'm sure. I just have linited NW view and not to the full meridan so it makes drift alignment much more challenging for me.
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The answer is that the two have nothing to do with one another. Polar alignment is simply the means by which you make your mount's polar axis parallel to the earth's rotational axis. Precession doesn't afffect polar alignment, because the whole earth wobbles - including you and your mount.
As stated earlier, levelling does not affect polar alignment. A level mount makes it 'easier' to polar align, by limiting the affect that the adjustment of one axis has on the other. However, you can polar align without a level mount.
A mount is a very dynamic system. It is possible that it is 'flexing' out of alignment in various parts of the sky - particularly if you have a heavy instrument on a small mount, loose screws, floppy optics etc. etc.
Have fun !