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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sumner's Line (Navigation question)
From: George Huxtable
Date: 2006 Feb 17, 09:30 -0000
From: George Huxtable
Date: 2006 Feb 17, 09:30 -0000
In the mailing I sent last night on this topic I made a careless mistake when I wrote, at the end, about working a time-sight- | | To work the problem by a calculator, rather than with logs, it's easier to use another expression | from Bowditch para 2106, | | cos (HA) = (sin lat - sin lat sin dec) / cos lat cos dec, | | and then convert angle to hours by dividing by 15. | | Again, lat and dec should be North-positive. ============= That expression should have read- | cos (HA) = (sin alt - sin lat sin dec) / cos lat cos dec. It makes a big difference. Sorry about that. George.
