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    Article on Equation of Time
    From: Frank Reed
    Date: 2014 Apr 8, 09:24 -0700

    There is a very brief article on the equation of time by David Berson today at the Ocean Navigator web site: http://www.oceannavigator.com/Web-Exclusives-2014/Equation-of-time/

    No serious errors that I can see... He does suggest that the equation of time is partly due to the variable rate of rotation of the Earth, and that might be considered an error in the historical meaning of the equation of time, but I could go either way on that. In any case, the variable rotation of the Earth is just a small fraction of a second difference in any given year, while the other two factors add up to about a half hour of variability. That's the best reason not to mention the variable rotation rate of the Earth: it's trivial compared to the changing angular speed of the Sun across the sky from January to July and the semi-annual declination effect.

    The primary influence of the equation of time in "modern" celestial navigation is now hidden in the Sun's GHA, so most navigators are unaware of its impact. In traditional celestial navigation (the "Old Navigation", before GHA), it was front and center.


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