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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: B-II Celestial Computer & Three-Minute Adjustments
From: Gary LaPook
Date: 2025 Feb 21, 15:19 -0800
From: Gary LaPook
Date: 2025 Feb 21, 15:19 -0800
Why would anybody prefer a three-minute schedule? Why not two minutes and thirty-seven seconds, that makes just as much sense. A four minute schedule has an inherent advantage as that the GHA of the sun turns exactly one degree in four minutes which simplifies some computations. This also works for star sights since Airies advances one degree-zero-point-2-minutes in four minutes of time. Using the four minute schedule only introduces a 120 foot error in longitude at the equator and only 60 feet at midlatitudes.
That is why HO 249 has a four minute adjustment table, to make it quick and easy. But..but..but "three-minutes," hunh?
gl
