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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Sextant calibration (arc error)
From: Frank Reed CT
Date: 2005 May 14, 23:24 EDT
From: Frank Reed CT
Date: 2005 May 14, 23:24 EDT
I experimented with a method for testing arc error last week. Off southeastern Connecticut there are numerous lighthouses seemingly at every direction around the horizon. So I measured all possible horizontal angles between five of them and then compared. I'm still looking at the results, but for those of you who want to look for arc error, this seems to be a good way to do it. It follows from the simple fact that the angles should add up: if the angle from lighthouse A to C is 120.1 degrees while the angle from A to B is 50.0 degrees and the angle from B to C is 70.0 degrees, then there must be arc error up around the high end of the sextant arc. This sort of thing might serve as a consistency check for tests done with star-star distances, etc. -FER 42.0N 87.7W, or 41.4N 72.1W. www.HistoricalAtlas.com/lunars
