The American nautical almanac, Volume 1911

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Page 257 - 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 266 - In the case of total and annular eclipses, a rough estimate of the magnitude of the eclipse may be obtained from the position of the place relatively to the central line and to the limit. On the central line, the eclipse is annular or total, while on the limit, the limb of the moon only grazes that of the sun. More Accurate Computations.
Page 263 - 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.
Page 225 - The sign + prefixed to the hourly change of declination indicates that north declinations are increasing or south declinations are decreasing. The sign — indicates that north declinations are decreasing or south declinations increasing. 226 GREENWICH MEAN TIME. MAY. JUNE. Month. •я Apparent Right Ascension. Var.
Page 258 - The sidereal hours are counted from 0 to 24, commencing with the instant of the passage of the true vernal equinox over the upper meridian, and ending with its return to the same meridian. About March '21st of each year the sidereal clock agrees with the mean time, or ordinary clock, and the former gains on the latter about 3"1 56...
Page vii - ... to the chronologists, to the 747th, and, according to the astronomers, to the 746th year, before the birth of Christ...
Page 93 - The semidiameter for mean noon may be assumed the same as that for apparent noon. The sign -+- prefixed to the hourly change of declination indicates that north declinations are increasing; the si^n — indicates that north declinations arc decreasing.
Page 264 - By a table of common logarithms, or a table of logarithms of small arcs, the reduction of the Greenwich time would be found thus: — From Ephemeris . . . . . . . PL 0.3276 Diff. of distances, 8' 35" = 515
Page 263 - Time, given at the end of the volume for 1871, saves 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 second difference, take the difference between the PL of Diff! used and the one which follows it in the Ephemeris, (or, more strictly, half the difference of the preceding and following ones).
Page 257 - Moon, the obliquity of the ecliptic, the nutation, the positions of 383 standard stars, the ephemeris for the meridian of Washington, etc. TIME. Astronomers make use of three different kinds of time, namely: First, true or apparent solar time; second, mean solar time; third, sidereal time. True or Apparent Solar Time. — This species of time is called indiscriminately either true solar time or apparent solar time, and is measured by the motion of the true Sun; the length of the...

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