NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Star - Star Observations
From: George Huxtable
Date: 2010 Mar 11, 11:11 -0000
From: George Huxtable
Date: 2010 Mar 11, 11:11 -0000
Brad wrote- Now for the fun part, I have two objects already selected. My location N40d 53.0m W72d 48.0m GMT 10-March-10 00-57-00 Object 1: RA 6h 45.22m Dec -16.7175 Object 2: RA 9h 27.68m Dec -8.6678 Therefore D = 40d 21m 12.41s H1 = 28.63501 d H2 = 37.80218 d a1 = 0.03025 d a2 = 0.02135 d Corner Cosines factor 1 = 0.43592 factor 2 = 0.02371 And consequently d, Corner Cosines = 40d 22m 1.7s d, Youngs = 40d 24m 45.84s I find a difference of 2m 44.14s between the two computations. The first assumption is that I erred again (a too often occurrence IMHO) ! The second assumption is that Young's equations are rigorous while the corner cosines are only an approximation, therefore a small difference is to be expected and that Young's equations are the ones to follow. Some further commentary would certainly be helpful! =================== Comment from George. We need to resolve some serious discrepancies first. I take the two stars to be Sirius and Alphard. From 40º53'N, on 10 March 2010, at 0hrs 57 min GMT, I get the predicted altitude of both stars to be a few minutes less than 32º. Not anything like the values given by Brad, of Sirius 28.63501º, Alphard 37.8021º. One of us is doing something wrong. Is it Brad, or is it me? George. contact George Huxtable, at george@hux.me.uk or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.