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Aldebaran Aldebaran W Antares W Apparent Declination apparent noon APPARENT PLACES Apparent Right Ascension Aquarii Arietis ASCENSION AND DECLINATION Auriga beginning Cancri Capricorni Center Ceti computed CONSTANTS OF STRUVE Date eclipse Equation Frid FRIDAY Geminorum given GREENWICH MEAN NOON h m h m Hour July June JUPITER W Latitude Leonis Libræ Logarithm longitude LUNAR DISTANCES Mean Solar Date Midnight Minute MONDAY Month Moon MOON'S RIGHT ASCENSION Motion Name and Direction Ophiuchi P. L. of Diff Piscium Pollux Reduction Regulus Right Declina Sagittarii SATURN Scorpii Semi semidiameter Sept Sidereal Spica W star STRUVE AND PETERS Subtracted SUN W SUN'S SUNDAY Tauri Thur THURSDAY tion Ascension tion North tion South TRANSIT AT WASHINGTON Tues TUESDAY UPPER TRANSIT VENUS Virginis WASHINGTON MEAN WEDNESDAY ΙΟ
Page 530 - 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 536 - 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 529 - 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 530 - 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 535 - ... letter W. or E. is affixed to the name of the sun, planet or star, to indicate that it is on the west, or east side of the moon. An observer on the earth's surface having measured a lunar distance, corrected it for errors of his instrument and for the...
Page 535 - Greenwich mean time, beginning at noon; the dates are therefore astronomical. All the distances that can be observed on the same day, are grouped together under that date; and the columns are read from left to right, across both pages of the same opening. The letter W. or E. is affixed to the name of the sun, planet or star, to indicate that it is on the west, or east side of the moon. An observer on the earth's surface having...
Page 531 - If great exactness is desired, we find the amount of this hourly difference for the time which is half way between Greenwich noon and the time of observation; that is, for 6 hours after Greenwich noon of the 2nd, this being half of 12 hours.
Page 534 - Columns adjoining those of the horizontal parallax give the change of that quantity in one hour, by means of which it can be reduced to any other Greenwich mean time, in the same way as the Sun's declination and the equation of time in the preceding examples. The sign plus or minus is prefixed to the hourly differences, according as the horizontal parallax is increasing or decreasing.