NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Advancing LOPs for precision fixes
From: Peter Hakel
Date: 2010 Feb 16, 12:14 -0800
From: hch <h.halboth@yahoo.com>
To: NavList@fer3.com
Sent: Tue, February 16, 2010 8:20:41 AM
Subject: [NavList] Re: Advancing LOPs for precision fixes
From: Peter Hakel
Date: 2010 Feb 16, 12:14 -0800
As John Karl writes in his book:
"The Nautical Almanac gives an iterative procedure for calculating a fix from several intercepts and azimuths determined from their St. Hilaire sight reductions."
I would add that this procedure does take the vessel motion (assumed to be constant during the round of observations) into account. I am confident that I am simply restating a fact that is well-known among NavList members. Also, I think it is not unreasonable to assume that the content of the Nautical Almanac reflects common (standard, recommended, accepted, etc.) practice.
Peter Hakel
From: hch <h.halboth@yahoo.com>
To: NavList@fer3.com
Sent: Tue, February 16, 2010 8:20:41 AM
Subject: [NavList] Re: Advancing LOPs for precision fixes
Gary,
You said ... "It is common practice to ignore the movement of the ship during the time period needed to take a round of sights ...", and I am unable to dispute this assertion in the light of today's "it's good enough" approach to Celestial Navigation. I can, however, state in no uncertain terms that this was not the traditional approach - LOPs generated in a round of sights were always advanced or retarted to a common time, so long as the distance run between individual sights was measurable, if for no other reason than professional pride.
Regards,
Henry |
