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    Re: lat/long from meridian passage
    From: Antoine Couëtte
    Date: 2011 Jan 23, 23:33 -0800

    RE : http://www.fer3.com/arc/m2.aspx?i=115413
    [NavList] lat/long from meridian passage
    From: goold---edu
    Date: 22 Jan 2011 20:43


    Dear Patrick,


    From your own data, summarized as follows :

    22 Jan 2011 (TT-UT=67.2 s) SUN Local Apparent Noon
    Fixed Position T=-4�C, P=1013.25 mb/Hpa = 29.92", Height of Eye = 0 ft
    All Heights "H" herebelow are "as would be observed in the Sextant and corrected for only instrument error",

    1 - UT=17h00m00.0s H=33�08'0
    2 - UT=17h15m00.0S H=33�18'0
    3 - UT=17h17m00.0s H=33�17'8
    4 - UT=17h19m23.0s H=33�18'0
    5 - UT=17h34m20.0s H=33�08'0

    Without knowing your position I derive the following results :


    SUN transit, i.e. "crossing" the Observer's Meridian happened at Time UT = 17h17m00.3s

    Observer's Position : N36�49'3 W076�21'9
    Standard deviation of your 5 data set : 0.7 NM
    Uncertainty in Longitude (1 Sigma) = 2'6

    EXCELLENT LUCK for your first Local Apparent Noon Observation. Your CelNav Observed Position falls quite close (0.7 NM !!!) from your actual GPS position recorded as N36�50'0 W076�21'7

    Also - and as just recently noted too by Jeremy - Latitude determination is generally (very) much better than Longitude determination when performing LAN's Observations, a fact which has long been recognized. See in particular "Calculator Navigator" by M. Mortimer Rogoff.

    Best Regards


    Antoine


    Antoine M. "Kermit" Cou�tte

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