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    Re: instances of the use of "horizon grazing" technique
    From: John Huth
    Date: 2009 Oct 23, 14:06 -0400
    Brad -

    Exactly!!!    What amazes me is the long shelf-life of these.  

    For the record, I actually tried this technique as an experiment in late October last year, and was off by 300 miles of latitude - it is only "reliable" (and I use the word advisedly) near the solstices.   My house had a good view of the horizon of both rising and setting sun, and, yes, I applied a correction for refraction, as if that mattered.

    Also - for the record - in the approximation where the solar declination doesn't change over the course of 24 hours, the equation is:

    Lat = arctan( (cos (d/2))/tan(decl))

    Where d = length of day in degrees or radians.     It obviously breaks down when decl=0.    Try remember this and calculate this on a life raft.

    John H.

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