American practical navigator: an epitome of navigation and nautical astronomy (1914)
Bowditch, Nathaniel, 1773-1838, United States. Navy Dept. Bureau of Equipment, Logan, George Wood, 1868-1915 · Washington, Govt. Print. Off. · leaf 125
rth, is ZAS;seen from C it is ZCS; the parallax is the dif-ference of these angles, ZAS —ZCS=ASC. Parallax in altitude is, then, the angle atthe heavenly body subtended by the radiusof the earth. If the heavenly body is in the horizon asat H, the radius, being at right angles to AH,subtends the… … Fig. 47. Let par. = parallax in altitude, ASC; Z = SAZ, the apparent zenith distance (corrected for refraction); R=AC, the radius of the earth; and D==CS, the distance of the object from the center of the earth. Then, since SAC = 180°-SAZ, the triangle ASC gives: R sin Zsm par. = j^—. If the object…
Navigation · Nautical astronomy
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