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    Re: suggestion for a satisfactory celnav narrative
    From: George Huxtable
    Date: 2005 Jun 4, 08:41 +0100

    Bill Noyce wrote-
    >Perhaps the fact that "longitude by noon sun" comes up so often
    >is a good reason that there *should* be a discussion of this
    >method, pointing out why it is a bad idea...
    >Is there any other observation that gives longitude without
    >knowing latitude first?  Maybe this is part of its appeal.
    To my mind, finding latitude at noon is a trivial matter that presents a
    problem only when the sky is cloudy at noon.
    To answer Bill's question, if a time-sight is taken at the moment when the
    Sun is due East or due West of the observer, then his latitude isn't needed
    at all in calculating local time-by-the-Sun. But that can only happen in
    the Summer months.
    But why, in this age, does a mariner still ask for separate determinations
    of latitude and longitude? It's as if we were still stuck in the early
    1800s, and Sumner and St Hilaire had never invented position lines. Why not
    just measure two altitudes of the Sun, at any old times, but times which
    are well separated so that the Sun's azimuth has changed significantly
    between them. Then draw a couple of position lines from some assumed
    position, allow for vessel's run in the interval, see where they cross, and
    that's where you are, in lat and long. Simple as that. Applies to any sight
    of any body at any time: a universal way of doing the job. Who needs
    anything different?
    contact George Huxtable by email at george@huxtable.u-net.com, by phone at
    01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
    Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.

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