The American Ephemeris and Nautical Almanac

Front Cover

Other editions - View all

Common terms and phrases

Popular passages

Page 356 - In the year 1887 there will be four eclipses, two of the Sun and two of the Moon. I. — A Partial Eclipse of the Moon, February 7-8, visible at Washington and also in the Pacific Ocean and part of Asia.
Page 465 - 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 465 - Passage shows the hour, minute and tenth of that passage of the planet over the meridian of Greenwich which occurs next after the noon of the date. The right ascension and declination of a planet are required whenever it is observed for time, latitude or azimuth. The mode of reducing the ephemeris positions of planets to other instants of Greenwich mean time is the same as that given for the Sun on pages 554 — 555.
Page 465 - Solar time is that used for all the purposes of ordinary life, and is measured by the daily motion of the sun. A Solar Day is the interval of time between two successive transits of the sun over the same meridian; and the hour-angle of the sun is called Solar Time.
Page 465 - It also comprises twenty-four hours, but they are reckoned from о to 24, and run from the noon of one day to that of the next following. Astronomical time as well as civil time may be either apparent or mean, according as it is reckoned from apparent noon or from mean noon. The civil day begins twelve hours before the astronomical day; therefore the first half of the civil day corresponds to the last half of the preceding astronomical day, and the last half of the civil day coincides with the first...
Page 357 - The regions within which the eclipses of the sun are visible are laid down on the accompanying charts, from which, by means of the dotted lines, the Greenwich mean...
Page 467 - On very rare occasions an emersion might be seen in the east horizon, or an immersion in the west, when this difference is a few minutes less than an hour. 3. The sun must not be much more than an hour above the horizon at the local mean time T — Л, unless the star is bright enough to be seen in the day time.
Page 465 - Sun for that time, and this being added to the local astronomical mean time will give the sidereal time. The sidereal time of mean noon, reduced for the longitude of the place, is also used in converting sidereal time to mean time. Subtracting the reduced value from the given sidereal time...

Bibliographic information