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    Re: Unexpected USNO height correction precepts
    From: Andrés Ruiz
    Date: 2018 Sep 18, 16:58 +0200
    Hello dear Antoine,

    Interesting disquisitions!

    With a marine sextant, in sights for altitude or lunar distance, I have always treated Venus as a bright spot.
    It is true that sometimes you can see its phase with a 7x50 binoculars, or a good sextant telescope. But I never worry about that.

    So for me: Beating around the bush!


    18/03/1977
    00:02:17 UT1

    Bap = -27.583333 º = -27º 35.0'
    Lap = 144.895000 º = 144º 53.7'

    NAUTICAL ALMANAC
    Venus
    GHA = 156.142468 º = 156º  8.5'
    Dec = 16.316548 º =  16º 19.0'
    SD = 0.4181 '
    HP = 0.4406 '

    ALTITUDE CORRECTION
    Limb: center
    Ref: SeaHorizon
    Hs = 18.0617 º =  18º  3.7'
    ic = 0.0000 '
    heas = 4.5720 m
    T = 10.0 ºC
    P = 1010.0 hPa
    Hoi = 18.0617 º
    dip = 0.0627 º
    Ha = 17.9989 º =  17º 59.9'
    R = 0.0499 º
    OB = -0.00000816 º
    HP = 0.0073 º
    PA = 0.00697593 º

    Without SD correction:
    Ho = 17.9561 º =  17º 57.4'
    Marcq St. Hilaire LoP
    LHA = 301.037468 º = 301º  2.2'
    Hc = 17.9689 º =  17º 58.1'
    Zn = 59.8 º
    p = Ho-Hc = -0.012863 º = -0.771794 '

    With SD correction:
    Ho = 17.9561 º =  17º 57.8'

    Best regards and fair winds!
    --
    Andrés Ruiz
    Navigational Algorithms
    http://sites.google.com/site/navigationalalgorithms/

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