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    Re: True Distance vs. Observed Distance
    From: Brad Morris
    Date: 2012 Sep 17, 14:54 -0400

    Well, that certainly clears up my confusion when the objects are 180 degrees in azimuth.

    Is this true for all azimuthal arrangements?   For example, when 90 degrees apart in azimuth?  Now when 0 degrees in azimuth?

    Do the corner cosines ever produce a negative result?  That is, when I add the corner cosine result to the observed (or subtracted from the GC distance) is the corner cosine addition result in a subtraction due to the sign of the number? 

    All of these questions are a function of getting it wrong the first time around.  Dang!  Now I get to do it all over again. 

    Brad Morris

    On Sep 17, 2012 12:48 PM, "Greg Rudzinski" <gregrudzinski@yahoo.com> wrote:

    Linked is a diagram showing how refraction changes observed distance between celestial bodies. For the diagram the bodies have a distance about 45* with the zenith directly above the observer. The refraction correction is added to the observed distance to get a true distance. If starting with a true distance from a GC calculator then the refraction correction is subtracted from the true distance to get the observed distance.

    Greg Rudzinski
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