Theory and Use of Astronomical Instruments. Method of Least Squares (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. 1891 Excerpt: ... upon 0 0', and the mean of the four microscopes gave the circle reading C0 = 359 59' 54."70 (or--0 0' 5."30) The micrometer thread was then brought alternately north and south of its own image in the collimator, so as to form each time a square with the middle transit thread and its image (as in Art. 147), and the micrometer readings were as follows: M = 5' 86f 85 so that M was the reading when the micrometer thread was in coincidence with its image. The telescope was then directed to Polaris at its upper culmination by setting the finder at 229 32' (the latitude being 38 59', the declination 88 32', and the refraction 1', approximately), and at the time of the star's transit, the micrometer thread bisecting the star, there were found Circle reading C = 229 32' 7."47 Microm. M' = 5r 50.G The value of one division of the micrometer was 0."927. Hence C'--C 229 32' 12." 77 M'-M0 = + 13."75 = +12.75 '(iV) = 229 32 25.52 This is the apparent nadir distance upon the supposition that the position of the reading microscopes (which rest on the axis of the telescope) remained absolutely fixed while the instrument revolved from the nadir to the star. To determine this, the spirit level was applied to the microscope frame. At the nadir reading, the inclination of the frame was?' =--1."23, and at the observation of the star it was i' =--1."54; and hence we have (JV) = 229 32' 25."52 f--i0 =--0.31 JV'= 229 32 25.21 In this observation, the circle was east, and the nadir distance was reckoned through the south point. 197. Since C and M0vn be applied in reducing all the observations made on the same day, or so long as these quantities are regarded as constant, it will be convenient to combine ...