NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: On the Mischief of Geographical Position.
From: Dave Weilacher
Date: 2002 Jan 24, 1:14 PM
From: Dave Weilacher
Date: 2002 Jan 24, 1:14 PM
..and BTW, what does gravity have to do with determining your position with sextent and chronometer? Original Message: ----------------- From- Michael Wescott wescott_mike@EMC.COM Date: Thu, 24 Jan 2002 14:49:20 -0500 To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM Subject: Re: [NAV-L] On the Mischief of Geographical Position. daveweilacher@earthlink.net wrote: >> It is the >> ZENITH that the navigator is attempting to locate in the celestial >> sphere. Once that has been accomplished, he projects it down via the >> local vertical, simply by renaming declination latitude, and GHA >> longitude, and calls it his position . This works on an egg, a pear, a >> lemon or an onion. Rodney Myrvaagnesreplies: > This is rigorously true, but it dodges the question that I think > people meant to ask, vis: If the local vertical (gravitationally > determined) doesn't point to the center of the earth or the celestial > sphere, then where is the position so measured? The actual (meaning the astronomical) latitude and longitude of a place is what is measured. In other words, the position so measured is exactly that place where it is measured. Due to local gravitational anomalies there may even be other places nearby with the same astronomical latitude and longitude. -------------------------------------------------------------------- mail2web - Check your email from the web at http://mail2web.com/ .