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    Correcting an Out of Date Nautical Almanac
    From: Greg Rudzinski
    Date: 2019 Oct 9, 07:56 -0700

    Appendix H pages 697 - 699 of the 1981 Bowditch vol. 2 does a decent job of correcting Nautical Almanacs that are multiples of 4 years out of date. For the Sun GHA and declination use the quad correction for the needed date multiplied by the number of four year multiples out of date (example: the 2007 NA would use Sun look-ups summed with the quad correction x 3  for use in the year 2019). For Aries use the column D value of appendix H for the number of 4 year multiples to sum with the out of date NA  Aries look-up (example: the 2007 Aries correction value would be +5.5' for use in the year 2019).  For star SHA and declination corrections multiply the annual correction in appendix H by the total number of years the NA is out of date.

    Why not keep a photo copy of Bowditch appendix H with out of date Nautical Almanacs as a useful book mark.

    Greg Rudzinski

       
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