A Manual of Spherical and Practical Astronomy; Spherical Astronomy Volume 1

A Manual of Spherical and Practical Astronomy; Spherical Astronomy Volume 1

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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. 1874 edition. Excerpt: ... 42 33.9a from Greenwich. 233. Corresponding observations at places whose difference of longitude is greater than two hours.--Having found a, and a2 as in the preceding case, we employ in this case an indirect method of solution. For each assumed longitude we interpolate the right ascension of the moon's limb from the Moon Culminations in the Ephemeris to fourth differences. Let A, Aa = the interpolated right ascensions of the moon's limb for the assumed longitudes Z, and L, respectively, If the correction of the Ephemeris on the given day is e, the true values of the right ascension for Lx and L2 are Ay + e and At + ', the error of the Ephemeris being supposed to be sensibly constant for a few hours; but their difference is (A, + e)-(Al+e) = A, -Al so that the computed difference of right ascension is the same as if the Ephemeris were correct. If now the observed difference a%--a, is the same as this computed difference, the assumed difference of longitude, or L2--Lv is correct; but, if this is not the case, put r =(-.-., )-(A-AJ (408) and d.L = the correction of the uncertain longitude, which we will suppose to be Lt then r is the change of the right ascension while the moon is describing the small arc of longitude &L; and for this small difference we may apply the solution of the preceding article, so that we have at once Az =-L. (in hours) (409) or QOAA L.L--yY. (in seconds) (409) in which the value of H must be that which belongs to the uncertain meridian L2, or, more strictly, H must be taken for the mean longitude between L2 and L2 + A-L; but, as Az is generally very small, great precision in H is here superfluous. However, if in any case &L is large, we can first find /Tfor the meridian L2, and with this value an approximate...show more

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  • Paperback | 164 pages
  • 189 x 246 x 9mm | 304g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236585941
  • 9781236585943