NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Latitude AND Longitude by Noon Sun
From: George Huxtable
Date: 2004 Jan 24, 00:56 +0000
From: George Huxtable
Date: 2004 Jan 24, 00:56 +0000
Frank Reed has described a method for determining the maximum altitude around noon. But what is needed for a simple calculation is the moment of local apparent noon (LAN). This is NOT the same as the moment of maximum altitude. The two are the same only when the vessel has no North or South component of velocity and when the Sun's declination is constant (at the solstices). He then, correctly, addressed the question of the Sun's changing declination, but ignored the (potentially much-greater) effects of the vessel's velocity. I suggest that it's important, even for a sailboat, to consider the effects of any North-South component of velocity on the time-difference between maximum Sun altitude and LAN. This was discussed in section 2 of my posting, of 23 Jan 2004, in the thread "Re: [NAV-L] Timed Noon sights for position". It's a matter that has otherwise been generally ignored in the recent discussions on this topic. George. ================================================================ contact George Huxtable by email at george@huxtable.u-net.com, by phone at 01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. ================================================================