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    Re: Swinging the Arc
    From: Alexandre Eremenko
    Date: 2004 Dec 5, 16:40 -0500

    On Sun, 5 Dec 2004, Frank Reed wrote:
    
    > 3) Swinging the "right" way by rotating about the line of sight
    > to the Sun.
    > Sun's image remains essentially centered in the field of view.
    
    How can you possibly do this in practice??
    Except by invereting your sextant and looking at the Sun through
    the horizon mirror?
    
    I mean when you look through the telescope how can you feel the
    correct direction to the Sun to swing about it?
    
    Maskelyne also asks the same question and concludes that one
    has to rotate the sextant about BOTH horizontal and vertical axes.
    When the altitude is small it is enough to rotate
    about horizontal axis,
    when it is large, the main part of the motion is about the
    vertical axis.
    
    Alex.
    
    
    

       
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