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    Re: "Super-Lune du siècle"
    From: Frank Reed
    Date: 2016 Nov 21, 19:40 -0800

    Ed Popko, you wrote:
    " Thus, for D1, I subtract my off-arc reading from 60? "

    Yes. There are two kinds of people in the world: people who do this in their heads without really thinking about it, and people who explicitly read the number from the micrometer and then subtract from 60 in a separate step. Neither side is "better" than the other. Just different ways of doing it. The "subtract from 60" methodology is perhaps safer when doing Sun-limb index correction tests because it's an easy mistake to make. If the IE is nearly zero, then both the on-arc and off-arc values will be close to 32 minutes of arc. The sextant reading is 32' off when the nominal value displayed by the micrometer is 28' in an off-arc case.

    Frank Reed

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