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    Re: Almanac
    From: Geoffrey Kolbe
    Date: 2002 Mar 25, 19:17 +0000

    Bowditch used to publish a "Long Term Almanac" for the sun and selected
    stars, all on a few pages. But I think that the 1984 edition was the last
    edition to contain it.
    All is not lost however. With sailors such as Aubrey O'Callaghan in mind,
    where the predicted use of celestial navigation is deemed too occasional to
    warrant the annual renewal of a full Nautical Almanac, I have published a
    "Long Term Almanac 2000-2050 For the sun and selected stars"
    The tables for the sun are based on the four year cycle to which others
    have alluded, and give the GHA and Dec at 00 hrs each day for the four
    years 2000 to 2003. The GHA of Aries is also given.
    Also given are quadrennial corrections so that each of the tables may be
    used for dates exactly four years hence and multiples thereof.
    By applying a single quadrennial correction factor, accuracy to about 0.3'
    can be maintained for 50 years. This accuracy is sufficiently good that
    observational error will still dominate in normal celestial navigation
    usage. Too, the Almanac is good until 2050, which should see most of us
    out. And it should fit in the sextant box!
    The other usual tables for refraction, dip, and how to find the GHA of the
    sun and Aries for any other time of the day are also given.
    A "short" sight reduction method with tables is also provided. The method
    is one of my own devising. But having devised it, I discovered that I had
    re-invented Ageton's method, with a few small differences!
    The book is not long, but neither is it short on explanation. Plenty of
    examples are given.
    Give it a try...
    Geoffrey Kolbe.
    Dr Geoffrey Kolbe, author of "Long Term Almanac 2000-2050" for sun and
    selected stars, with concise sight reduction tables.
    Available online from www.pisces-press.com

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