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    Mathematical Advancement of a celestial COP
    From: John Brenneise
    Date: 1998 Oct 23, 3:39 PM

    I have some code that takes the place of H.O. 229 or H.O. 249 by
    numerically solving the following:
    
    sin(h1) = cos(phi)cos(beta1)cos(theta-alpha1) + sin(phi)sin(beta1)
    sin(h2) = cos(phi)cos(beta2)cos(theta-alpha2) + sin(phi)sin(beta2)
    
    where  h1 is the corrected angle of elevation for a circle centered
    at latitude beta1, GHA alpha1 and h2 is the corrected angle of
    elevation for a circle centered at latitude beta2, GHA alpha2.
    
    
    The question concerns running fixes.
    
    The COP from the earlier of the two observations must be advanced
    along the DR course.  In terms of the center of the circle, I propose
    that (beta1,alpha1) must be moved along the loxodrome defined by
    the course angle for a distance to be scaled by a factor related to the
    difference between the course angle and the azimuth angle to the
    celestial object.
    
    
    So, what I need is a good reference and or insight on Spherical
    Trigonometry to test my assumption.
    
    Any ideas?
    
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