NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sun sights during an eclipse: "bad limb" calculation
From: David Pike
Date: 2023 Oct 10, 14:53 -0700
From: David Pike
Date: 2023 Oct 10, 14:53 -0700
Just to start the ball rolling, here is my estimate of time to 0.5’ error in LL, which will probably be completely wrong.
On 14th Oct 2023, the Sun will be overtaking the Moon in the horizontal plane at 15x60 - (14x60 + 34) minutes/hour = 26’/hr. For small differences in the bottom of a circle, in losing 0.5’ vertically, the horn travels root (16x16 -15.5x15.5)’ = root (256-240.25) = root 15.75 = 4’ horizontally. Time taken for 0.5’ error = 4x60/26 = approximately 9 minutes of time. For 0.1’ it’s about 4 minutes of time. All + or – about 41%. It must be a bit like plotting the Sun through noon to get longitude. For a long time in the middle, you hardly seem to get any movement vertically, well not with a peri-sextant. DaveP
