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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Star-star distances for arc error
From: Bill Morris
Date: 2009 Jul 3, 13:36 -0700
From: Bill Morris
Date: 2009 Jul 3, 13:36 -0700
Frank You wrote, in commenting on R B Gordon's paper in the Journal of the Royal Institute of Navigation (1964) 17. pp 125 - 147: "The author describes his attempts to measure INDEX ERROR using stars. He describes his miserable results which he clearly cannot explain, and then from that experience he asserts (without evidence; without data; much as you have done) that star-star sights for arc error wouldn't work. He has ZERO data on the topic of using star-star distances for arc error." What you say about his lack of data is fair enough, but isn't estimating index error by using a star the simplest case of a star-star sight? If one accepts this, may we then accept that sights using two stars are likely to have similar errors? In my case, using a SNO-T sextant with x6 telescope clamped atop a theodolite tripod the standard deviation of index error observations using a star was 0.17 minutes (n = 30). I am not a fan of Galilean 'scopes and Gordon seems to have been particularly unlucky with his if he found "...a star image will superimpose over a range of 5'." Bill Morris Pukenui New Zealand --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---