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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Parallactic retardation - don't give up so easily.
From: George Huxtable
Date: 2004 Jan 9, 19:44 +0000
From: George Huxtable
Date: 2004 Jan 9, 19:44 +0000
Bill Noyce wrote, supported by Fred Hebard- >Imagine you and I take a lunar sight at the same instant. You >measure the apparent distance exactly correctly; I have an error >of 1'. If parallactic retardation is severe, our cleared distances >will differ by nearly 2'. Yes, Bill, I agree that the nub of the matter lies there. But if the effect of the clearing process is to ADD (or subtract) a correction, mostly as a result of changing parallax, won't it add the same small angle to my observation as it does to your observation, keeping the difference as 1'? The approximate method of clearing the distance, which we know works, depends on calculating an increment to apply to the apparent distance. Why should that increment differ in the two cases? Do argue back if you think I am wrong. It's a funny position to be in, arguing against my previous convictions, and so needing to convince those who agreed then that they were wrong too. I am by no means certain that I am on firm ground. George ================================================================ contact George Huxtable by email at george@huxtable.u-net.com, by phone at 01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. ================================================================
