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Author
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Topic: 100 Problems in Celestial Navigation
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brokesailor
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posted February 02, 2015 12:27 PM
I am trying to use this book to practice celestial. On problem 1 he precomputes the stars to be taken. When he solves for LHA of Aries he uses LMT for civil twilight. Shouldn't it be done using GMT?
From: ChesBay
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David Burch
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posted February 02, 2015 02:14 PM
We cannot evaluate another book or investigate their style of cel nav.
Please refer to our text Celestial Navigation for the ways we recommend.
Also please note there is an errata for that book which we have somewhere on our website. Might try searching the home page master search engine.
Note too this may be a matter of terminology rather than differences in procedure. ie we do not use the term LMT, but simply refer to the times in the nautical almanac as the GMTs of the events observed from Greenwich.
To us the concept of LMT only asks for trouble and there is no need for it in practical cel nav.
in fact, during the entertainment section of our course we read the Bowditch Definition of LMT, which you can look up online. all of Bowditch is online.
From: Starpath, Seattle, WA
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David Burch
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posted February 02, 2015 02:19 PM
To save some time on the above suggestion, here is the official definition
local mean time
The arc of the celestial equator, or the angle at the celes-
tial pole, between the lower branch of the local celestial meridian
and the hour circle of the mean sun, measured westward from the
lower branch of the local celestial meridian through 24 hours; local
hour angle of the mean sun, expressed in time units, plus 12 hours.
Local mean time at the Greenwich meridian is called Greenwich
mean time, or Universal Time.
From: Starpath, Seattle, WA
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brokesailor
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posted February 03, 2015 01:19 AM
Thank You Dave!
From: ChesBay
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