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    Re: Longitude by Sunset
    From: Greg Rudzinski
    Date: 2012 May 7, 08:25 -0700

    Alex,

    -26.4' is what my Palm Pilot Software used for refraction. The Henning Umland online sight reduction produces the same intercept value if 50 F is entered for temperature. At a temperature of 70 F then the intercept increases to 1.1' (see attachments). The ocean temperature here is 60 F and the air temperature was 70 F at the time of the observation. Lots of strange mixing goes on at the surface of the ocean so inconsistencies should be expected.

    Greg Rudzinski


    [NavList] Re: Longitude by Sunset
    From: Alexandre Eremenko
    Date: 7 May 2012 10:01
    Greg,
    What value of refraction did you use
    for the Sun upper limb at sunset ?
    And where did you take it from?

    Alex.

    On Sun, 6 May 2012, Greg Rudzinski wrote:

    >
    > Grabbed a few snaps of todays sunset and low level fog and haze obscures
    limb tangency with the horizon. I was able to get a LOP from an image that
    has the upper limb 39.8' above the horizon using my pixel counting and
    minutes of arc per pixel method. The intercept was 1.0' T with azimuth
    290.7*. This is a good result considering that the Sun is so squashed. (200mm
    lens)
    >
    > Greg Rudzinski
    >

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