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    Re: Longitude by Sunrise
    From: Jeremy C
    Date: 2010 Feb 2, 22:59 EST
    I just got the message today.  I don't subscribe so I don't know about the hard issue or when it might appear. 
    Vis horizon LOPs turned out very poorly for me this past trip.  I had intercepts of 5.9' for the UL and 4.1' for the LL. using the standard values from the NA and the GPS fix as the AP.
    In a message dated 2/2/2010 10:52:04 P.M. Eastern Standard Time, jhkarl@att.net writes:

    Without a sextant and timing the green flash, why not just work up the traditional St, Hilaire LOP at zero UL observed altitude?? It's independent of an assumed latitude, which was after all, Sumner's 1837 epiphany.

    Sure the altitude corrections are a little less reliable when the sun is 50' below the horizon, but I think it's better than fussing with sunset times.

    BTW Jeremy, was the piece published in Ocean Navigator? If so, when? Currently, Ocean Nav is sitting on a short article of mine on the above zero-altitude LOP.


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