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Subject: Re: Calculators...it is a shame the moon's motion is so complicated
From: Gene W (genewun@XXX.XXX)
Date: Fri Sep 03 1999 - 07:01:17 EDT
>But, the sun is also the most useful body. You may need no more. (It is a
>shame the moon's motion is so complicated. It woudl be a good second body.)
>
>Bill Murdoch
Hi Bill
Check out this book. You may find it interesting.
Regards
Gene Wunderlin
-----------------------------------------------
TABLES FOR CLEARING THE LUNAR DISTANCE
by Bruce Stark
Think of the satisfaction of aiming your sextant at the moon and
determining time
(GMT) accurately! You can do this anywhere- at sea, in the mountains-
no natural or
artificial horizon is needed. This is the old method of "lunars"
which was used by
mariners (and explorers) to reset their clocks almost until the
beginning of the 20th
century.
Because the moon moves much slower across the sky than the stars, its changing
position can be used in sort of a reverse process of sight reduction
to find the time. The Nautical Almanac no longer has tables of
precomputations for finding the time based on the distance between
the moon and certain selected stars as it once did. Instead, this
book can be used with the modern Nautical Almanac to find the time in
this way with quick and easy computations. That is not to say,
however, that making the observations are so easy. The practicing
navigator will appreciate the opportunity to use the sextant in this
additional way, and the challenge it presents. Even amateur
astronomers may enjoy this interesting pursuit.
The present justification for celestial navigation is that it
provides a backup when
electronics fail. Since electromagnetic shock from a nearby
lightening strike can derange timekeepers as well as electronics, the
celestial solution which includes "lunars" becomes even more powerful.
This book includes a motivating preface, and complete instructions on
its use, as well
as coaching on the observations themselves. SoftCover, 8.5x11 inches
spiral bound, 301 pages, 1997. SW 2.5 lbs.
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