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    A Nautical Almanac question
    From: Stan K
    Date: 2016 Nov 23, 18:52 -0500
    Is the d value listed at the bottom of the sun and planets columns of the daily pages of the Nautical Almanac the average (or mean) hourly change in the sun's declination for the three days listed (as stated in the Nautical Almanac and other references) or the amount the declination changes between 1200 and 1300 on the middle day of the three shown (as stated in Bowditch)?

    I did one page of the sun values in the 2017 Almanac and found that, after rounding to tenths of an arc-minute, the average was 1.0', the change between 1200 and 1300 on the middle day was 1.0', and the value at the bottom of the declination column was 1.0'.  I suspect that I would find the same thing on other pages, but I'm curious if anyone knows for sure.  My suspicion is that Bowditch is correct, and the references using "average" or "mean" are just simplifying the explanation.

    Stan

       
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