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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Mathematical Advancement of a celestial COP
From: Buck Godwin
Date: 1998 Oct 23, 10:24 PM
From: Buck Godwin
Date: 1998 Oct 23, 10:24 PM
On Fri, 23 Oct 1998 14:39:07 -0700, you wrote: > >The COP from the earlier of the two observations must be advanced >along the DR course. In terms of the center of the circle, I propose ... strange you should mention this just hours after i was reading an article in Navigation, The Journal of the Institute of Navigation. according to the article, the problem of obtaining a direct fix from 2 observatinos with an advanced (or retired) COP has not been solved analytically. in a nutshell, assuming the observer moves along a rhumb line, you have to advance each point on the COP along a loxidromic spiral to its new locus. the new loci no longer lie on a circle, so the algorithm is not strictly valid. the 1997 article by Stanley W. Gery references 4 other articles between 1977 and 1981 in the same publication on the same subject. as a practical suggestion, take a run of sights on body 1 and a run on body 2. pick a time between the two runs. extrapolate the first set forward and second set backward to the chosen time. Buck Godwin =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-= TO UNSUBSCRIBE, send this message to majordomo@roninhouse.com: =-=-= navigation =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-
