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Re: Position discepancy
From: Gary LaPook
Date: 2011 Dec 13, 13:00 -0800

I don't know exactly what you are saying. Did you take observations of Polaris and Jupiter with a sextant? Bubble sextant? Marine sextant? sea horizon? artificial horizon? Did you make all the necessary sextant corrections? Did you reduce the sights using the Navy calculator with your known position?

http://aa.usno.navy.mil/data/docs/celnavtable.php

We need more information.

gl

--- On Tue, 12/13/11, Fred Stevens <fredstevens@yahoo.com> wrote:

From: Fred Stevens <fredstevens@yahoo.com>
Subject: [NavList] Position discepancy
To: NavList@fer3.com
Date: Tuesday, December 13, 2011, 10:43 AM

I have a known location... well, "known" as far as Google
Earth goes. I am assuming that it is a correct position
since it is verified by GPS. When I go to either the NA or
online almanacs, like USNO Almanac or Henning Umland's to
verify the coordinates using Jupiter and Polaris, there is
always a significant discrepancy between them and those from
GPS/GoogleEarth, a few nautical miles at the very least.
Enough to be worrisome if at sea.
Any idea why so much difference?

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