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    Re: Angular Distance Between Stars By Camera and Sextant
    From: Brad Morris
    Date: 2012 Sep 18, 13:48 -0400

    If I am measuring star-to-star distances, then I fail to understand how dip of the horizon is important

    Shouldn't the calculated altitude of the two objects be sufficient to determine the refraction? 

    Dip would be part of reducing the measured altitude, no?

    Best Regards

    On Sep 18, 2012 1:04 PM, "Marcel Tschudin" <marcel.e.tschudin@gmail.com> wrote:
    Andrés, you clarified

    On Tue, Sep 18, 2012 at 7:08 PM, Andres Ruiz <navigationalalgorithms@gmail.com> wrote:

    Hc = Hc( B, L, Dec, GHA )
    Z  = Z( B, Dec, Hc, LHA( L, GHA ) );
    iterate to find Hs ( Hc = Ho = Hs + IE - dip - R )
    Ha = Hs + IE - dip;
    R = Refraccion( Ha, T, P );

    Ok, yes, I completely forgot that your program is for verifying sextant observations and does therefore more than just calculating the difference in star coordinates. However, since both star positions contain the same dip this should have no influence on the calculated star distance. The difference of 0.4 moa still waits to be understood.

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