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Between any two points on the Earth's surface can be traced three different curved lines: a Great Circle Arc, a rhumb line and an isoazimuthal. The line or curve called isoazimuthal "IsoZ(X,θ)", is the locus of the points on the earth's surface whose initial orthodromic course with respect to a fixed point X, it is constant and equal to θ. (It is also called capable spherical arc) That is, if the initial orthodromic course from S to X is 80 degrees, the associated isoazimuthal line is formed by all points whose initial orthodromic course respect point X is 80 °. == From a star== In this case the X point is the illuminating pole of the observed star, and the angle θ is its azimuth. The equation of the ''isoazimuthal'' curve (or capable spherical arc),〔Le segment capable sphérique. Navigation Nº.116 Vol.XXIX, Institut français de navigation, Oct / 1981.〕 for a star with coordinates (Dec, Gha), -''Declination'' and ''Greenwich Hour Angle''-, observed under an azimuth Z is given by: where lha is the local hour angle, and all points with latitude B and longitude L, they define the curve. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Isoazimuthal」の詳細全文を読む スポンサード リンク
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