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    Re: Eclipse computations with Lunar4
    From: Frank Reed
    Date: 2016 Oct 11, 11:14 -0700

    Paul Hirose, you wrote:
    "For utmost accuracy, check the "Moon center of figure correction" box. It applies the standard correction of +.5″ longitude and -.25″ latitude to the center of gravity positions that you get from an ephemeris. The Astronomical Almanac eclipse data includes this correction, but I don't think it's important and in fact didn't use it in the above computations."

    Straight out of the 1950s! Unfortunately, this center of figure correction is seriously antiquated. With or without it, you will not get the sort of accurate eclipse data that will be relevant to resolving minor disagreements over the duration of next summer's eclipse. We now have highly accurate DEM (digital elevation model) data for the lunar surface, derived from unmanned spacecraft observations in the past decade. Despite the enormous and impressive effort you have put into your "Lunar4" software, you have neglected the single most important advance in lunar timings in a century. To address this deficit, you'll have to abandon your peculiar design principle of making your product smaller than a megabyte (which matters to no one in the world, except as a stunt, in the year 2016), but in principle it's not too difficult. This could potentially make your prediction data world-class. You're only one step away. I do understand that this involves "getting into the dirt" of the Moon --literally. Many people who enjoy creating astronomical software balk at the unpleasantness of mountains and valleys on the lunar surface. It's so un-astronomical. But fear not! It's a nice clean dataset amenable to the same exacting calculations and geometric principles that provide pleasure in more ethereal astronomical computations.

    Frank Reed
    Conanicut Island USA

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