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    Re: The Star of Bethlehem and Navigation
    From: George Huxtable
    Date: 2009 Jan 4, 11:38 -0000

    Marcel Tschudin wrote-
    | I would have assumed that the information on the eclipses would
    | provide information on both, deltaT and nutation. May be someone who
    | has the article on how deltaT was evaluated can be more precise.
    | Geoffrey?
    
    I haven't been following this "Star of Bethlehem" business, but the most
    respected workers in this field of understanding past delta-T have, for some
    years, been Morrison and Stevenson, and I attach a definitive paper on the
    topic from 2004. It gives several other references. I can't help with more
    recent references than that one.
    
    Marcel doesn't need to worry about the effects of nutation, which are
    cyclic, so never build up to more than a fraction of a minute. The tilt of
    the Earth's axis with respect to the ecliptic, however, decreases
    progressively by about 8 arc-minutes per millennium, in a way that's very
    precisely calculable.
    
    contact George Huxtable, at  george{at}hux.me.uk
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
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