|
|
|
|
|||||
|
||||||
Subject: Re: Timing noon.
From: George Huxtable (george@XXX.XXX)
Date: Wed Apr 10 2002 - 04:31:03 EDT
Walter Guinon said-
>When declination and Latitude are changing appreciably perhaps the most general
>method of estimating the time of local noon is:
>1) Take altitude measurements of the sun when you can, hopefully between
>sunrise and sunset.
>2) The clock time of noon is that which gives a least mean squares fit of this
>altitude/time data to the computed altitude at the DR position.
George Huxtable responds-
This, to me, is a bit too general to be really helpful. I wonder if Walter
Guinon could be a bit more specific, please, about points 1 and 2.
Should the navigator spend the whole day measuring, or are there times that
are more useful than others?
What is the "DR position" that he refers to, and what measurements has it
been derived from? Having chosen that position, how does he make the
least-squares fit?
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?
------------------------------
george@XXX.XXX
George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
Tel. 01865 820222 or (int.) +44 1865 820222.
------------------------------
|