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    Re: Lunars: how to use the prop.log tables?
    From: Robin Stuart
    Date: 2016 Sep 1, 07:29 -0700

    Tony,

             Thanks for raising this topic and to Ed for his explanation. These arcane proportional logarithms are something I had not encountered before. Since you haven’t had an answer to your follow up question here’s what I notice.

    Ed has clearly done the correct calculation but appears to have made a simple transcription error when writing it up and as you point out chose not to make use of the prop logs in the Almanac. Here’s a modified segment of the explanation at http://fer3.com/arc/m2.aspx/Lunars-how-use-proplog-tables-EdPopko-aug-2016-g36381

    -------------------------------------------------------------------------------------------

    Using your post data ...

    12:00 UT, 84° 35'.2, PL 2620

    pLogD =   2620

    and ...


    d is total change in LD distance from First time (12:00) to your unknown time of lunar sight
    d = 84° 35.2' - 83° 00.0'
      = 1 35.2'
    Looking 1 35.2' up in table ...
    pLogd = 2766

    Thus ...

    --------------------------------------------------------------------------------------------------

    The difference between 2623 calculated directly and 2620 from the Almanac propagates through and changes the final result slightly

    Regards,

    Robin Stuart

       
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