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    Re: About Lunars, part 3 (correction)
    From: George Huxtable
    Date: 2002 Feb 15, 23:42 +0000

    In my reply to Chuck Griffiths, sent a few minutes ago, there was an error
    which needs correcting.
    What I said was-
    "Try this out on a globe of the world, in exaggerated form. Forget about
    the continent-markings on it, we aren't using it as a model of the World,
    just as a sphere to show up the spherical geometry. In fact, we only need
    the upper hemisphere.
    The equator represents the plane of the observer's horizon, and the
    observer is at the centre of the globe.
    Mark a spot at say zero longitude, 30 N latitude, and another at 90
    longitude, 30N latitude. These spots represent the two stars, in GHA and
    altitude.  Measure the distance between the spots (the interstellar
    distance) with a piece of string, along the shortest path (a great circle).
    This length corresponds to the length of the ars between the two stars as
    seen by the observer..."
    Where I referred to the spots representing two stars "in GHA and altitude",
    I should have said "in azimuth and altitude". The globe, as a model, makes
    more sense that way.
    Oh, and where I aid ars, it should have been arc, of course!
    Sorry about that.
    George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    Tel. 01865 820222 or (int.) +44 1865 820222.

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