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    Re: Small booklet of EOT and Dec
    From: Frank Reed
    Date: 2018 May 21, 09:18 -0700

    Yes, such things have existed in a variety of forms through the decades. You can find tailored tables of this sort published annually even today in Eldridge's Tide Tables, for example. Many short tables existed, but most were intended only for short-term or "lifeboat" use. Some USN Mk II sextants from the 1940s included short tables of dec and equation of time printed on bakelite plastic and glued into the top of the sextant case.

    In all my celestial classes, I supply long-term Sun data either as equation of time (in minutes and second) and Declination (in degrees and minutes) or as GHA and Dec at Greenwich midnight (both in decimal degrees). Note that GHA Sun at any fixed GMT, whether midnight or noon or any other, is functionally equivalent to th equation of time. It's possible to use one year of tables through four years if you apply a rule that adjusts the GMT by 6,12, or 18 hours based on the year. Personally I don't think this is worth the economy: you can print one year with the added complexity of this rule on a single-side of a standard page of paper, but you can just as easily print the full four years, without the special rule on two standard sheets of paper double-sided. These tables can be used with minimal loss in accuracy for up to two leap year cycles (yielding a total of twelve years from two sheets of paper).

    Speaking of classes, my last of the season is this weekend at Mystic Seaport Museum: Modern Celestial Navigation.

    Frank Reed

       
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