NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Z tangent formula
From: Peter Fogg
Date: 2005 Jul 11, 10:30 +1000
From: Peter Fogg
Date: 2005 Jul 11, 10:30 +1000
> From: george huxtable > But Peter makes it difficult (indeed impossible) for anyone else to > reproduce his calculation, by omitting mention of the values of hour- > angle, > lat, and dec that he has used. If Peter will provide that missing-link, he > might get some more informed responses. Here we go: >The first comes from the problem Mike Burkes >posed, that I worked out and posted here on the 2 July. > >Sun UL Azimuth - in decimal form, and to 3 decimal places if available >101 'Bennett book' azimuth tables >100.9 Sharp nav. calculator >100.982 NavPac, given as 100d 58.9' >100.985 Z tan formula 287d 02' LHA N36d 00' lat S00d 57' dec 13d alt I think I've been able to answer my own question. NavPac (and the nav. calculator) use internally generated values of declination and Local Hour Angle (dec S00d 56.7', LHA 287d 02.1' for NavPac) which could explain the small discrepancy. Substituting these values in the Z tan formula gives an azimuth of 100.9810198d, or 100d 58' 51.6". The answer quoted above of 100d 58.9' could simply be the same answer rounded slightly. Nevertheless, am interested in finding other formulas for the calculation of azimuth for comparison.