The American Ephemeris and Nautical AlmanacU.S. Government Printing Office, 1911 - Nautical almanacs |
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Common terms and phrases
1.0 Mean Solar 9 ΙΟ Apparent Declination APPARENT PLACES Apparent Right Ascen Arietis ASCENSION AND DECLINATION Auriga Besselian Boötis Camelop Cancri Cephei Ceti CIRCUMPOLAR STARS Cygni d h m D'ya Day of Month Decl Declina Mean Right Diff Draconis Dw a Dy eclipse Ephemeris Eridani Geminorum GREENWICH MEAN NOON Groombridge h m h m Heliocentric Herculis Horizontal Parallax Hour II.I II.N July June Latitude Leonis Libræ longitude Majoris Mean Place Mean Right Declina Mean Solar Date Merid meridian MOON'S RIGHT ASCENSION North Observatory Octantis Ophiuchi Parallax Pegasi Piscium PLACES OF CIRCUMPOLAR Right Declina Mean Sagittarii Scorpii Semidiameter Sept Sidereal sion Sun's Tauri Thur tion N tion Solar Ascen TRANSIT AT WASHINGTON 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 708 - 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 702 - 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 - When the time of observation is only a few hours before Greenwich noon, it may be better to count the longitude backward from this nearest noon. Thus, in the example just given, the time iß 11.978'' before Greenwich noon of May 3; half this interval is about 0.25 of a day, and the hourly motion for the middle of the interval is 44.52".
Page 701 - 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 iii - Greenwich, gives the ephemerides of the sun and moon, the geocentric and heliocentric positions of the major planets, the sun's coordinates, and other fundamental astronomical data for equidistant intervals of Greenwich mean time ; Part II, Ephemeris for the meridian of Washington gives the ephemerides of the fixed stars, sun, moon, and major planets for transit over the meridian of Washington ; and Part III, Phenomena, contains predictions of phenomena to be observed with data for their computation.
Page 702 - 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.
Page 706 - Page III contains, for Greenwich mean noon of each day, The Sun's True Longitude and Latitude, and the Logarithm of the Radius Vector of the Earth. The longitudes of the Sun are the true geometric longitudes, not corrected for aberration. They are given in two columns, headed, respectively, A.
Page 98 - The sign +• prefixed to the hourly change of declination indicates that north declinations are increasing and south declinations are decreasing.
Page 708 - The heliocentric latitude is counted from the true ecliptic of the date The Logarithm of Radius Vector is the logarithm of the distance of the center of the planet from that of the Sun, at the Greenwich mean noon whose date is given in the first column. The last two columns give, respectively, the logarithm of the true distance of the center of the planet from that of the Earth, for the Greenwich noon indicated on the...