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    Refractional flattening of sun or moon
    From: Marcel Tschudin
    Date: 2010 Apr 3, 10:57 +0300

    In the thread "Sun Moon Lunars to 155 degrees" Antoine mentions that
    this effect should be included when clearing navigational
    observations.
    
    My first reaction was "no", at least not more than what you do by
    considering the refraction obtained from one of the various empirical
    transfer-functions which calculate the refraction as a function of
    altitude. It is the highly non-linearity of those functions near the
    horizon which cause this flattening. The refraction at the LL is
    higher than at the UL, the flattening is thus caused by the refraction
    difference which is already considered when using one of those
    transfer-functions.
    
    However, Frank mentions in his reply: "Today, oblateness and
    refractional flattening are as easy to include as any other aspects in
    the lunars clearing process so by default they are "on" in the
    clearing tool on my web site." What do you mean here Frank? Are you
    really doing more than just applying the "normal" refraction? Could it
    be that you eventually correct the empirical refraction values
    obtained from the transfer-function according to e.g. the body's
    height to width ratio measured at different altitudes?
    
    Marcel
    
    
    
    

       
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