NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: AP terminology, WAS: 2-Body Fix -- take three
From: Frank Reed
Date: 2009 Nov 12, 23:18 -0800
From: Frank Reed
Date: 2009 Nov 12, 23:18 -0800
John, you wrote: "If we can't agree on the label for this point, let's call it the "controversial Point", the CP." Let's see... I think it's called Z, isn't it? ZPS triangle?? And which point do you choose for its Z (projected onto the celestial sphere)? In some methods you can use the DR (or the EP if you define these differently, or a GPS position if you have one since it then *immediately* gives you an estimate of your sight errors). In other methods you choose a specific "AP" to get the numbers to work out right. I have long felt that there are too many of these acronyms floating around, just on aesthetic grounds, whether they're a source of confusion or not! :-) And John you wrote: "Then, for List members, I can rephrase my favorite question: Why does the St. Hilaire method use a CP instead of just calculating the LOP directly? (I think Frank says there's no confusion on the answer to this question.)" Did I say that? Really, I'm not entirely sure just what you're trying to ask here, so I maybe I should stay neutral on whether there's confusion on this :-). Of course, celestial navigation has always been taught as a "practical art". Students learn it, understand the underlying principles in some sense varying from completely clear, for the geometrically clever, to hazy at best, for the geometrically challenged. Point being, it's not taught like math of physics, from first principles. It's taught to get the job done. Because of that tradition (which may be historical now), there's bound to be confusion about the "real" reasons for doing things among many navigators who know how to do the practical work with perfect competence and confidence. -FER --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com -~----------~----~----~----~------~----~------~--~---