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    Re: Compare Methods: Lat/Lon Near Noon
    From: Herman Dekker
    Date: 2021 Sep 15, 13:40 -0700

    Lat/Lon near Noon one other way to calculate it.

    I thought I calculated Frank’s problem by the TI-89 calculator with Starpilot program.

    First calculate with CoarseMadeGood and SpeedmadeGood program the result of boat and current movement.

    Outcome Course 158° Speed 4,3 Kt


    The TI-89 calculator asks the DR position and the HE , for the sight reduction
    that is not given so I had to calculate roughly myself.

    I am educated by Frank LAT=ZD + Dec. ZD= (90°-Ho)
    I choosed the sight with max measured height.
    UT 16:39 Hs=73,075° Ho=73,075+0,216=73,291°

    Almanac for 22-mai-2022 midday gave about Dec=20,44
    Sun shadow points North. So LAT=+ZD + Dec

    LAT=(90°-73,291°) + 20,44=37,15° N
    Noon is around max. measured height at ~UT=16:39
    Converted UT to Lon, at UT 16:39 Lon = 69,75° W
    For HE, reverse calculated from given info HE=8,3 feet

    Now typed al six sights in the Sight reduction program.
    Then simplistic did Fix by computation at UT 16:39:15 and the answer is:
    LAT 37°11,4’ N
    LON 70° 12,5 W
    Even as the lops cross under shallow angles, a good result.

    At UT 17:00:00 the position is:
    LAT 37°10’N
    LON 70°11.8’W

    This my contribution on the Noon problem.
    HermanD

       
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