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Old 17-06-2015, 03:34 AM
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Dark sky rules !

skysurfer is offline
Join Date: Dec 2011
Location: 52N 6E (EU)
Posts: 1,150
Best polar alignment star ?

For astrophotography I use a polar scope of the Vixen Super Polaris mount of 25 years old. There is a template in it showing northern Polaris plus the trapezoid consisting the south pole star sigma Octantis, but calibrated for epoch 1990.

But due to the precession the template is outdated but the arc minute scale and the center cross (which should match the celestial pole) are still usable.

So in the northern hemisphere I put the cross to 40' from Polaris at the right RA.

In the south I use BQ Octantis, much closer to the pole (only 14' now, 10' in 2027) which is +6.9 and easily visible in the polar scope. No such star visible in the polar scope exists closer to the North pole than Polaris.

And, when using BQ set to 14' off-pole at the proper RA, the mount is very well polar aligned.

Does somebody use this star as polar alignment ?
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