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    Fwd: Sextant Accuracy and anomalous dip.
    From: Peter Fogg
    Date: 2003 Mar 18, 13:24 +1100

    
    > From: Gary Harkins 
    > Imagine yourself on top of a mountain taking a sight.  Imagine that 
    > the sight measures 45 degrees using a bubble horizon or artificial 
    > horizon.  At sea level and the same geographic location (if that were 
    > possible) the sight would measure higher.  If you measured the same 45 
    > degrees at sea level you would have to be further away from the sun's 
    > GP.
    Only by the difference of distance? Since the distance to the celestial 
    sphere is, by definition, infinity it would not seem to matter? Sun and 
    esp. Moon corrections include factors for parallax, the difference 
    between taking sights from the surface rather than the centre of the 
    earth. Is it related to that?
    >   I hope that's clear, it's easier to show using a sketch.
    Yep, its a real challenge to explain these concepts using only words. 
    Can only imagine (hope) that one day it will be as quick and easy to 
    include a crude sketch as it is now to type text.
    
    
    
    

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