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    Re: Sextant accuracy (was : Plumb-line horizon vs. geocentric horizon)
    From: Bill B
    Date: 2005 Feb 20, 20:16 -0500

    > So if I were to use a distant power line (or other narrow straight feature) to
    > get the index correction of my sextant, I should be able to get very accurate
    > results. But what about the sea horizon? Can the eye detect discontinuities in
    > the visual horizon (which is not a line but instead a boundary between light
    > and dark) with the same hyperacuity?
    
    Question.
    
    Given the problem with using a near object is parallax error created by the
    index mirror being higher than the horizon glass.
    
    Could one use a nearer power line at some measurable distance, and adjust
    that IC with a parallax correction using the vertical distance between the
    centers of the index and horizon mirror vs. the distance from the power
    line?
    
    Bill
    
    
    

       
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