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    Re: Difficult observations
    From: Ronald P Barrett
    Date: 2009 Nov 20, 09:51 -0800
    As a long time flight nav (old), I know from an aviation point of view, in the weather, night, turbulent flying, star observations to be difficult, especially with a hand held sextant as flown in the 30s and early 40s. Even worse was a sextant with no averager! One great improvement that was so simple: was the sky-hook. You could they hang onto the sextant and be somewhat more stable in your effort to get a sighting. An even worse condition was when the battery that supplied power to the bubble lamp went dead... you were all but sunk! I often wonder if that was Amelia Earhart's Nav-Noonan's problem on his long 20hr flight in to Howland Island. He had all of the above "worse conditions." Ron Barrett, President Air Force Navigators Observers Association (AFNOA)

    --- On Fri, 11/20/09, Anabasis <jcaoy---.com> wrote:

    From: Anabasis <jcaoy---.com>
    Subject: [NavList 10767] Difficult observations
    To: "NavList" <navlist@fer3.com>
    Date: Friday, November 20, 2009, 11:17 AM

        In the world of taking observations, as opposed to reducing them, I
    was thinking of the observations that are the most difficult to shoot
    at sea and thought that I’d make a short list.  I am wondering what
    others might think and how they rate different observations in order
    of observation difficulty.  I am not going to list such main stays as
    sun lines, azimuths, and upper transits.
        By difficulty I mean to not only observe them, but to get useful
    data.  In any case, here is the list of exotic sights that I’ve taken
    in order of difficulty

    1)    High altitude sights of the moon (Ho >89 degrees)
    2)    High altitude sights of the sun
    3)    Amplitudes of stars/planets
    4)    Amplitudes of the moon
    5)    Nighttime (by moonlight) star fix
    6)    Lower transit of a star (due mostly to low altitude)
    7)    Lunar distances

    I’d be interested in hearing what other sights have proven troublesome
    to navigators out there.

    Jeremy

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