# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Sunrise, Sunset, LAN, LMT
From: Dan Allen
Date: 2004 Aug 3, 17:30 -0700
Are you trying to determine the position of the sun at 12:00 GMT?

Or are you trying to determine "high noon" for a given location?

Tables are usually used.  The formulas to determine the position of the sun are about one page printed out.  They involve lots of calls to sin and cos.  Do you have tables of those as well?

I think the best pencil and paper almanac would be one with a print out for a year with values of GHA and Declination for each day of the year, or every other day to save space, and then you could interpolate between those values.  That is doable.

Am I answering the right question?

-- Dan

-----Original Message-----
Sent: Tuesday, August 03, 2004 12:17 PM
Subject: Sunrise, Sunset, LAN, LMT

I am slowly teaching my self celestial navigation.  I have a copy of Dutton, which many of you on this list recommended to me, and a downloaded copy of Bowditch.  I am working my way through noon sight and grasping the concepts, the online almanacs I am finding to be pretty good and easy to understand.

Now I come to my problem.  I downloaded a problem from the website www.oceannavigator.com entitled "Navigating without a clock."  This problem deals with a noon sight to determine latitude but there is no clock on the ship.  Lest anyone get to worried, the author of the problem does make several assumptions to make the problem solvable.

I have looked in a number of places for a paper and pencil method to determine GMT as well as sunrise and sunset.  I have found a basic computer program from Sky and Telescope magazine in 1994 which shows how to determine sunrise and sunset at a selected position, but so far no way to determine noon GMT.  I know that this information is provided in the nautical almanacs on the daily pages, but I am looking for a way to calculate this number using a pencil and paper.  I have a pretty good feeling this is going to be somewhat difficult, but I am willing to make the attempt.  I know that there are spreadsheets, and computer programs capable of doing this, but I am looking for pencil and paper

If anyone can direct me to a reference or a guide either online or in print I would greatly appreciate it.

I will keep plugging away at this.  Thanks for all your help.

Andrew

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