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. 1915 Excerpt: ... which 5 is the apparent declination and j is the latitude. If the latitude is accurately known, the resulting azimuth should be in error less than 05." Six place logarithms should be used. (4) If an error of 01' in the calculated azimuth of the line is allowable, points need not be set beneath the star. Instead, the ...
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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. 1915 Excerpt: ... which 5 is the apparent declination and j is the latitude. If the latitude is accurately known, the resulting azimuth should be in error less than 05." Six place logarithms should be used. (4) If an error of 01' in the calculated azimuth of the line is allowable, points need not be set beneath the star. Instead, the horizontal angle between the line of reference and the line of sight tothestar may be measured with circle right and circle left as in direct solar observations (Problem 51, p. 130). (5) A very satisfactory target for night work is a strongly illuminated card upon which a line has been drawn of sufficient weight to be clearly seen through the telescope from the observer's station. The source of illumination should be shielded from the observer, for otherwise the target will appear indistinct. (6) The time between sights to the star should be as short as possible, but there is no necessity for extreme haste in setting the ground points, since the azimuth of the star is changing very slowly. At latitude 400 this change amounts to about 01.5" when the star is 05TM from elongation, and about 06" when the star is 10m from elongation. (7) If it is necessary to observe Polaris when not at elongation but near that position, the correction to be applied to the azimuth at elongation is expressed approximately by C = o.o6w2 (for observations south of latitude 500) in which n is the time in minutes before Or after elongation and C is in seconds of arc. - More exactly the correction is o.052n2 for latitude 300. o.os8n2 for latitude 40, and 0.069M2 for latitude so0. Practical Applications.--Because azimuth determination by observation on Polaris does not depend upon a timepiece and because the horizontal movement of the star is comparativ...
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