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    Re: AM and PM time sights
    From: Herman Dekker
    Date: 2021 Nov 9, 13:06 -0800

    I came over this old post from David C and could first not understand what was wrong with the 2 calculated Longitude values.

    I asked Starpilot the correct Hc data for the date Time and DR sight and calculated the Longitudes.
    I then draw the position line and concluded (as David did) the longitudes are wrong but why?
    I used the calculation many times without problems.
    Then I realised that the rules learned in the Modern Celestial Navigation Class are not compleet
    for this case.
    If Longitude >360° subtract 360° If longitude<0° add 360°

    I think I need one extra rule.
    If calculated Longitude is >180° and <360° then Longitude is 360°-calculated, that is East Longitude.

    I wonder if the rule:If longitude<0° add 360° can be replaced with the rule:
    If Longitude<0° make value positive en write East Longitude.

    See attache Pdf's for Calculation and Plot.

    If I am wrong pleace comment.

    Kind regards

    HermanD

    File:
    Gen.Long-Sight-near-Dateline-outcome-01.pdf
    File:
    Gen.Long.Sight-PLOT-01.pdf
       
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