hour angle

The angular distance west of a celestial meridian or hour circle; the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of a celestial meridian or hour circle and the hour circle of a celestial body or the vernal equinox, measured westward through 360°. At any instant, hour circles are coincident with particular celestial meridian. There are three types of hour angles: sidereal, Greenwich, and local. The sidereal hour angle is the angle of the celestial pole between the celestial meridian of the first point of the Aries and the celestial meridian of the body, measured westward from the celestial meridian of the first point of Aries. The Greenwich hour angle is the arc of the equatorial measured westward through 360° measured from the celestial meridian of the Greenwich to the hour circle of the body. The local hour angle is the angle at the celestial pole measured westward from the observer’s meridian to the celestial meridian of the body.

Aviation dictionary. 2014.

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  • Hour angle — Hour Hour, n. [OE. hour, our, hore, ure, OF. hore, ore, ure, F. heure, L. hora, fr. Gr. ?, orig., a definite space of time, fixed by natural laws; hence, a season, the time of the day, an hour. See {Year}, and cf. {Horologe}, {Horoscope}.] 1. The …   The Collaborative International Dictionary of English

  • hour angle — n. Astron. the angle formed at the pole, or its arc on the celestial equator, between the hour circle of a celestial object and the observer s celestial meridian measured in hours, minutes, etc.: it represents the elapsed time since the object… …   English World dictionary

  • hour-angle — hourˈ angle noun (astronomy) The angle (usu measured as time) between the declination circle of a body observed and the observer s meridian • • • Main Entry: ↑hour …   Useful english dictionary

  • Hour angle — In astronomy, the hour angle is one of the coordinates used in the equatorial coordinate system for describing the position of a point on the celestial sphere.The hour angle of a point is the angle between the half plane determined by the Earth… …   Wikipedia

  • hour angle — noun 1. the angular distance along the celestial equator from the observer s meridian to the hour circle of a given celestial body (Freq. 1) • Hypernyms: ↑distance 2. (astronomy) the angular distance of a celestial point measured westward along… …   Useful english dictionary

  • hour angle — Astron. the angle, measured westward through 360°, between the celestial meridian of an observer and the hour circle of a celestial body. Cf. sidereal hour angle. [1830 40] * * * ▪ astronomy  in astronomy, the angle between an observer s meridian …   Universalium

  • hour angle — valandų kampas statusas T sritis fizika atitikmenys: angl. hour angle vok. Stundenwinkel, m rus. часовой угол, m pranc. angle horaire, m …   Fizikos terminų žodynas

  • hour angle — hour′ an gle n. astron. the angle, measured westward through 360°, between the celestial meridian of an observer and the hour circle of a celestial body • Etymology: 1830–40 …   From formal English to slang

  • hour angle — noun Date: circa 1837 the angle between the celestial meridian of an observer and the hour circle of a celestial object measured westward from the meridian …   New Collegiate Dictionary

  • Greenwich hour angle — hour angle measured from the meridian of Greenwich, England. * * * …   Universalium

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