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Subject: Re: Timing noon.
From: George Huxtable (george@XXX.XXX)
Date: Fri Apr 12 2002 - 01:09:08 EDT
In response to the following question about estimating the time of local noon-
>"As I see it, no other input is required than altitudes of the Sun
>measured
>at suitably chosen times, a knowledge of the North-South component of the
>ship's speed, and the rate of change of declination. Does Walter agree?"
Walter Guinon said-
>I think the E/W component of the ship's speed must also be incorporated in the
>solution.
Well, I doubt that, and invite Walter to reconsider his opinion. As I see
it, Easterly motion, against the Sun, increases both the rate of rise of
Sun's altitude before noon, and the rate-of-fall after noon, without
affecting the symmetrical moment of noon itself. The maximum altitude will
occur at the same moment for a vessel heading East as for a stationary
vessel. Similarly, Westerly motion reduces those rates of change. So such
motion has no effect on the result, though it may change the shape of the
curve that Walter's proposed method is trying to fit. Can he persuade me
otherwise?
George Huxtable.
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george@XXX.XXX
George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
Tel. 01865 820222 or (int.) +44 1865 820222.
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