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    Re: When did "time sights" fade away?
    From: Gary LaPook
    Date: 2011 Jul 21, 10:26 -0700

    The St. Hilaire and the time sight/azimuth methods will produce the same LOP only if the chosen AP for the St. Hilaire computation produces the exact same azimuth which will not normally be the case. However, since it is accepted practice to use an AP withing 30 NM of the DR we accept the slight inaccuracy in the final LOP as it is accurate enough for celestial navigation. The difference also disappears into the inherent errors of the observation. I posted before a study of thousands of observations taken by many experienced navigators and the standard deviation came out to about 1.5' so about a third of observations have errors greater than this. Bowditch, 1938, says to allow a two NM error band on each side of the LOP so the slight differences between these two methods, and with the Sumner method, can be ignored for practical navigation.

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