The American Ephemeris and Nautical AlmanacU.S. Government Printing Office, 1911 |
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Common terms and phrases
1.0 Mean Solar 9 ΙΟ Apparent Declination apparent noon APPARENT PLACES Apparent Right Ascen Aquilæ Arietis ASCENSION AND DECLINATION Aurigæ Besselian Boötis Camelop Cancri Capricorni Capricorni Cephei Ceti CIRCUMPOLAR STARS Cygni d h m D'ya Day of Month Decl Declina Diff Draconis Dwa Dy eclipse Ephemeris Eridani Frid Geminorum GREENWICH MEAN NOON Groombridge Heliocentric Herculis Horizontal Parallax Hour Angle II.I July June Latitude Leonis Leonis Libræ Logarithm longitude Majoris Mean Place Mean Right Decli Mean Solar Date Merid meridian Moon MOON'S RIGHT ASCENSION nation Solar Ascen North O.II Octantis Ophiuchi Pegasi Persei PLACES OF CIRCUMPOLAR Sagittarii satellite Scorpii Semidi Semidiam Semidiameter Sept Sidereal sion Sun's Thur tion tion N TRANSIT AT WASHINGTON True Equinox Tues UPPER TRANSIT Ursa Minoris Virginis WASHINGTON MEAN ΙΟ Ο.ΟΙ
Popular passages
Page xiii - the 2588th year since the era of Nabonassar, which has been assigned to Wednesday the 26th of February of the 3967th year of the Julian Period, which corresponds, according to the chronologists, to the 747th, and, according to the astronomers, to the 746th year, before the birth of Christ ;
Page 698 - The civil day begins at midnight and comprises 24 hours, the hours being counted from 0 to 12 in two scries, the first marked am running from midnight to noon and the second marked pm running from noon to midnight. The astronomical day begins at noon on the civil day of the same date, the...
Page 704 - 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 697 - Therefore clocks and chronometers can not be regulated to apparent solar time, which may, however, be determined by observations of the Sun when visible. Mean Solar Time is measured by the motion of a fictitious body called the mean Sun, which is supposed to move uniformly in the celestial equator, completing the circuit in one tropical year. Since mean solar tune is uniform and regular in its passage, clocks and watches may be regulated to it, and those in ordinary use are usually so regulated.
Page xiii - The year 1333 of the Mohammedan era, or the era of the Hegira, begins on the i gth day of November, 1914.
Page 702 - A column of hourly differences enables the computer to obtain the sun's longitude for any hour from noon. The hourly differences of the logarithm of the radius vector are likewise given. The latitude is referred to the ecliptic of the date.
Page 718 - H — \, taken without regard to sign, must be less than the semi-diurnal arc of the star by at least one hour. 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 699 - The heading of the column directs the manner in which the equation ig to be applied. When there is a change in the course of the month from addition to subtraction or the reverse (as in the months of April and June), the two different directions are separated by a line, while a corresponding line below points out the dates between which the change takes place.
Page xvi - Conjunction, or having the same Longitude or Right Ascension. D Quadrature or differing 90° in...
Page 698 - 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 half of the astronomical day of the same date. Thus, January 9, 2 o'clock, AM, civil time, is January 8, i4h, astronomical time; and January 9, 2 o'clock, PM, civil time, is also January 9, 2h, astronomical time.