**sidereal hour angle** — Astron. the angle, measured westward through 360°, between the hour circle passing through the vernal equinox and the hour circle of a celestial body. Cf. hour angle. * * * … Universalium

**sidereal hour angle** — noun : a coordinate in the equator system of coordinates used by navigators in place of right ascension, measured westward from the March equinox, and expressed in degrees up to 360° * * * Astron. the angle, measured westward through 360°,… … Useful english dictionary

**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 … Aviation dictionary

**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

**Sidereal hour** — 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** — 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** — 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

**Sidereal time** — is a measure of the position of the Earth in its rotation around its axis, or time measured by the apparent diurnal motion of the vernal equinox, which is very close to, but not identical to, the motion of stars. They differ by the precession of… … Wikipedia

**sidereal time** — n. 1. time measured by the sidereal day: it is divided into the sidereal hour (1/ 24 of a sidereal day), the sidereal minute (1/ 60 of a sidereal hour), and the sidereal second (1/ 60 of a sidereal minute) 2. the hour angle of the vernal equinox … English World dictionary