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Re: Polaris' PM in RA?
From: Roger W. Sinnott
Date: 2020 Sep 23, 18:29 +0000
From: Roger W. Sinnott
Date: 2020 Sep 23, 18:29 +0000
Sean,
When a star is near a pole, it is very important to apply the proper-motion adjustment BEFORE precessing the position away from 2000.0. (This is another way of saying the proper-motion components have equinox 2000.0 associated with them, just like the coordinates themselves.) This particular error drove me batty, many years ago, when working on the original edition of Sky Catalogue 2000.0.
Also, I don't think you mentioned nutation. Are you also correcting for that?
Roger S.
