. Tables of calculated hour-angles and altitude azimuth table 30N. to 30S. : ex-meridian tables 60N. to 60S. and calculated reductions ans azimuths of bright stars from 1 hour to 3 hours from Meridian / c by Blackburne . In the above-mentioned case it is recommended to calculate arc (2) after the azimuthhas been calculated by the following formula as deduced from the spherical triangle MZD,viz. :— Above-Pole Observation.—Tan arc (2) =cos Z . cot alt. Below-Pole Observation.—Cot arc (2) =cos Z . cot alt. As the azimuth is nearly always required to make use of an observation taken out ofthe
. Tables of calculated hour-angles and altitude azimuth table 30N. to 30S. : ex-meridian tables 60N. to 60S. and calculated reductions ans azimuths of bright stars from 1 hour to 3 hours from Meridian / c by Blackburne . In the above-mentioned case it is recommended to calculate arc (2) after the azimuthhas been calculated by the following formula as deduced from the spherical triangle MZD,viz. :— Above-Pole Observation.—Tan arc (2) =cos Z . cot alt. Below-Pole Observation.—Cot arc (2) =cos Z . cot alt. As the azimuth is nearly always required to make use of an observation taken out ofthe meridian, this last-mentioned formula is preferred to the foregoing one, and is in thewriters opinion the best formula for an ex-meridian latitude that he knows of. Foraccuracy the azimuth should be calculated by the following formula :—Sin azim. =sin cos decl. sec alt. CALCULATION OF EX-MERIDIAN LATITUDES. No. i MethodExamples to Illustrate each CaseCase No. i.— 3 h. 00m., decl. 22° o S., alt. 22° 2i-8 3h. 00m. Cos 9-84948 Decl. 22° o S. Cot 0-39359 Cosec 0-42642 Arc (i) 29° 44J S. Cot 0-24307 Sin 9-69558 Alt. 22° 2i-8 Sin 9-58033 Arc (2) 59° 44r 30° o N. Cos 9-70233. XXIV EXPLANATION AND USE OF TABLES Case No. 2.— 2 h. 40 m., decl. 50° N., alt. 54° z-G 2h. 40m. Cos 9-88425 Decl. 50° o N. Cot 9-92382 Cosec 0-11575 Arc(i) 57°i6N. Cot 9-80807 Sin Arc (2) 27° 16 S. Lat. 30° o N. 9-92490 Alt. 54° 2-6 Sin 9-90819 Cos 9-94884tablesofcalculat00blacrich
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