A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Bob Crawley
Date: 2017 Mar 1, 11:32 -0800
Frank - that was an interesting point you made which got me digging. From what I can gather from Wikipedia Annual aberration is around 20 arcseconds and the stars appear to move in circles at the poles (I suppose this could be a a change in SHA or DEC) and lines on the equatorial plane (i.e. a change in SHA). As you say this would make an interesting test to measure the interstellar angle at different times of year, perhaps with one star with high DEC and one with low. I think I'll figure out how to mount my sextant on a tripod (also good for Lunars I expect).
I then started comparing this with the monthly 173 stars in the Almanac and the figures are much bigger. I presume that this is due to Precession which accounts nearly an 1 arcminute per year. Is that correct or have I misunderstood?