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    A Lunar alternative?
    From: Peter Fogg
    Date: 2003 Oct 2, 15:59 +1000

    In his book 'Along the Clipper Way' Francis Chichester includes the story of
    how the ship 'Alert' found its way, with difficulty, around Cape Horn in
    mid-winter sometime before 1840. He then muses about the difficulties of
    observing and working a "lunar" then goes on:
    "...and then suddenly thought of a simple solution which I will explain
    briefly: make a simultaneous observation of the sun and the moon for
    altitude when the moon is nearly east or west. From this compute a sun-moon
    fix, using a guessed-at GMT. Now compute a second fix from the same
    observation but using a GMT which differs from the first by half an hour or
    an hour. Now establish the latitude by a meridian altitude of the sun or any
    other body as it crosses the meridian. This observation does not require
    accurate time. Now join the two sun-moon fixes and the point where the line
    joining them, produced if necessary, cuts the known latitude must be the
    correct longitude at the time of the observation. Knowing the longitude
    enables you also to know the correct GMT at the time of the sun-moon fix.
        I fear the accuracy of this method, which depends on the rate of
    movement of the moon in its orbit, would be poor, but it could be a most
    valuable observation ...."

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