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TABLES OF THE SUNN'S MEAN RIGHT ASCENSION. By WlL" 



LiAM Galbraith, A.M. Communicated hy the Author, 



The following Tables, adapted to the meridian of Greenwich, 

 have been computed by me, for the purpose of performing a 

 problem, of frequent occurrence in practical astronomy. 



They are founded on late investigations, are more accurate 

 than any with which I am acquainted, and are applied in the 

 following manner. 



Let m be the mean solar time at the place of observation, 

 s the corresponding sidereal time, 

 r the mean right ascension of the meridian, equivalent to the mean 



longitude of the sun, converted into time for the preceding mean 



noon at the place of observation. 

 a the acceleration of the fixed stars for the sidereal time s — r, from a 



table for converting sidereal into mean solar time. See XXXI. of 



my Mathematical Tables. 

 « the acceleration for the mean solar time m, by a table for converting 



mean solar into sidereal time. Table XXX. of my Mathematical 



Tables. 



Then»n = (« — r)— a (I) 



And « = r + m+« (2) 



Now, by Tables I. and II. for years, months, and days, find the mean 

 right ascension of the meridian at mean noon on the given day of any pro« 

 posed year, reckoned from the mean equinox. To this apply the equations 

 firom Tables III. and IV., of which the arguments are S3, O, and ]), and 

 the result will be the right ascension reckoned from the apparent equinox. 

 In the Nautical Almanac for 1834, and succeeding years, the sun's right 

 ascension at mean noon will be given, which will facilitate this problem. 



Example 1. — An eclipse of the first satellite of Jupiter was observed at 

 Greenwich on the 17th January 1825, at 2'' 19"* 49.0* sidereal time by a clock, 

 which was 69M4 fast. Required the corresponding mean solar time ? 



Sidereal time by the clock, . 

 The error of the clock fast, . 



Correct sidereal time, 

 VOL. XV. NO. XXIX. — JULY 1833. 



