The American Ephemeris and Nautical Almanac

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Page 410 - In the year 1887 there will be four eclipses, two of the Sun and two of the Moon. I. — A...
Page 495 - Mean Time, which is perfectly equable in its increase, is measured by the motion of this Mean Sun; the latter at certain periods agrees with the real sun, then again is in advance of it, and at other times is behind it.
Page 495 - Sidereal Time. — Sidereal time is measured by the daily motion of the stars; or, as it is used by astronomers, by the daily motion of that point in the equator from which the true right ascension of the stars is counted.
Page 501 - Time, given at the end of the volume for 1871, eaves the operation of reducing degrees, (or hours) and minutes to seconds, and the reverse. As the PL of Diff. in the Ephemeris varies, the Greenwich time, found by the methods just described, may not be sufficiently exact. To correct it for such variation, or 2d difference, take the difference between the.
Page 496 - ... mean noon. The civil day begins twelve hours before the astronomical day; therefore the first period of the civil day answers to the last part of the preceding astronomical day, and the last period of the civil day corresponds to the first part of the same astronomical day.
Page 496 - The Civil Day, according to the customs of society, commences at midnight, and comprises twenty-four hours, from one midnight to the next following. The hours are counted from 0 to 12 from midnight to noon, after which they are again reckoned from 0 to 12 from noon to midnight. Thus the day is divided into two periods of 12 hours each...
Page 518 - NEWCOMB'S Investigation of the Distance of the Sun and the Elements which depend on it,\ is 8".848. The adopted Semidiameter of the Sun at the Earth's mean distance is 16
Page 496 - Ascension and Declination, and the Equation of Time. Adjoining columns contain the differences of these quantities for one hour. By multiplying this difference by the hours and parts of an hour from Greenwich apparent noon, and adding the amount to. or subtracting it from, the quantity at noon, according as that quantity is increasing or decreasing, we obtain the value of any quantity for any given Greenwich apparent time.

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