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    Re: Longitude by Sunrise example
    From: Gary LaPook
    Date: 2010 Feb 04, 16:51 -0800

    The N.A. states that the table allows for a S. D. of 16' and a
    refraction of 34' (the value in the refraction table for zero altitude)
    so the Ho is actually -50' when the UL is on the horizon when observed
    from sea level. To this you would also have to allow for dip.
    Apache Runner wrote:
    > The typical correction at the horizon is around 30-some odd arc
    > minutes for refraction at the horizon.   The sun appears to be higher
    > in the sky than it really is.    So, that means that the sun is
    > visible after it has "set".   You would have to take a slightly
    > earlier time for sunset - say when the lower limb is 15 arc-minutes
    > above the horizon (since the diameter of the sun is approx. 32
    > arc-minutes).
    > Or something like that....
    > On Thu, Feb 4, 2010 at 4:32 PM, Marcel Tschudin
    > > wrote:
    >     Jeremy, I would like to give it an other try using the GPS data. What
    >     was the latitude, or did I miss it? Marcel

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