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    Re: AP terminology, WAS: 2-Body Fix -- take three
    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
    
    
    
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