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Subject: Re: Lunar distances
From: Eric Haberfellner (ehaberfe@XXX.XXX)
Date: Sun Jan 27 2002 - 22:16:28 EST
I recieved this message WS Murdoch. It provides more information on what is
in the Lechter Book.
Thank you Mr Murdoch.
Eric Haberfellner
-----Original Message-----
From: WSMurdoch@XXX.XXX]
Sent: Sunday, January 27, 2002 6:20 PM
To: ehaberfe@XXX.XXX
Subject: Re: Lunar distances
In a message dated 1/26/02 1:39:28 AM Eastern Standard Time,
ehaberfe@XXX.XXX writes:
I am not an expert on Lunars, but I believe that Lechter gives a complete
solution. He states:
"In discovering a way to solve it [GMT by lunar distance] using only the
Nautical Almanac and the ordinary sight reduction tables I had on board
(H.O. 214), I experienced one of the great intellectual triumphs of my
life.
On the 25th day of the passage, with 500 miles to go, I was able to prove
beyond all doubt that my clock was correct, within one minute of GMT, so
my
longitude was gound within 30 miles or so - ample precision for the
upcoming
landfall"
This was in 1963. Did the Nautical Almanac still have Lunar distance
tables
at that time? I will have to dig into this material to figure out what
information he actually uses from the Nautical Almanac. I don't have time
right now.
He has some equations, and gives complete examples.
Self Contained Celestial Navigation with H.O. 208 by John S. Letcher
contains two chapters on lunars. The first chapter (and method) is a
slightly simplified standard determination of the time by lunar observation
using a modern almanac. The second is the line of position method which has
been discussed on this list before. He describes his discovery of this
second method and dates it as 1963. He published the method in Yachting
(February 1964) previous to Chichester's 1966 Along the Clipper Way.
The line of position method needs nothing more than the normal almanac data,
a means of sight reduction, some plotting, a favorable alignment of the
moon, and enough bodies for a fix.
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