The Astronomical Ephemeris Volume 1855 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1852 Excerpt: ... below it: that is, in the instance referred to, the Equation of Time is to be added to Apparent Time from the 1st of April to the instant at which the equation becomes om o," which happens between the noons of the 15th and 16th days of the month; but after that instant the equation is to bp subtracted from Apparent to obtain Mean Time. Page II. of each Month. The Sun's Apparent Right Ascension and Declination at mean noon have been deduced from its Apparent longitude and latitude given at page IIL, and the apparent obliquity of the. ecliptic at page 242. They denote the apparent position of the true Sun with reference to the equator, and the true equinox, at the instant the Greenwich mean time clock, or chronometer, indicates o1' om os, or when the hour angle of the true Sun is equal to the equation of time. To find the Right Ascension and Declination for any other mean time and place, as at 9 l 20'" A.M. March 2, 1855, in longitude 980, or 6h 32m, West of Greenwich. The astronomical time, corresponding to 9h 20m A.M. March 2, is 2ih 20ra from the noon of March 1, or March id 2111 20m, agreeably to what has been said before. Thelongitude, being West of Greenwich, must be added to March id 2 ih 20"1, and the result, March 2d 31' 52'," is the corresponding Greenwich mean time, for which the Right Ascension and Declination are to be found. The difference between the Right Ascensions on March 2, and March 3, is 3"143s 94, that is, in the 24 mean hours succeeding the Moan Noon of March 2, the Right Ascension has increased by this quantity; it will, therefore, have received a proportional part of the increase in 3'" 52m, and the amount is readily obtained by this proportion 241' 3'" 43s'94:: 3h 52m: 36s-08; which, being added ...