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    Re: Long by Chron
    From: David C
    Date: 2016 Dec 7, 19:17 -0800

    A few days ago the weather cooperated and I managed to take a PM sight when the sun was on the prime vertical.

    ZT  171610

    ZD  2016/12/6

    Zone -13

    GMT 041610

    GD 2016/12/6

    ho  35° 50.1'

    GPS 41° 06.5'   175° 05.2'

    t  61 22'  by calculator

    GHA 246°  16.8'

    From which    long =  175° 05.2'  !!!!!!!!

    From Norie  A = .46      B = .46    C = 0

    so azimuth = N 90° W

    Error in long =  error  in lat * C = 0

    I recalculated t for lat +- 6' and confirmed that there was no error in long. A lat error of +-30' gave a small error in long.

    There isn't anything particularly amazing in the above except that it confirms what I learned four decades or more ago. A method used by 19th century navigators really does work!!!!!!!

    The telescopes on my sextant do not work (I am missing a tube) and usually I use a sight tube. For the above sight I used the binoculars with one objective covered with a piece of thick card. The larger images made it much easier to touch limbs.

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