# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 7 Search : coordinate system
 altazimuth coordinate system   راژمان ِ هم‌آراهای ِ فرازا-سوگان   râžmân-e hamârâhâ-ye farâzâ-sugânFr.: coordonnées azimutales   The coordinate system in which the position of a body on the → celestial sphere is described with respect to an observer's → celestial horizon and → zenith. The coordinates of a point in this system are its → altitude on the → vertical circle, and its → azimuth westward (clockwise) along the celestial horizon from the observer's south. Same as → horizon coordinate system.→ altazimuth; → coordinate; → system. coordinate system   راژمان ِ همارا   râžmân-e hamârâFr.: système de coordonnées   Math: A system for locating each point in space by a set of numbers. Astro: Values in a reference system used to relate the position of a body on the celestial sphere. Four main coordinate systems are utilized in astronomy: the equatorial, horizontal, ecliptic, and galactic coordinates systems.→ coordinate; → system. equatorial coordinate system   راژمان ِ هماراهای ِ هموگاری   râžmân-e hamârâhâ-ye hamugâriFr.: système de coordonnées équatoriales   An astronomical → coordinate system for indicating the positions of → celestial objects on the → celestial sphere. The system consists of two components, → right ascension and → declination. Right ascension is the angle between the → vernal equinox and the point where the → hour circle intersects the → celestial equator. The right ascension is always measured eastward from the vernal equinox, in the units of hours, minutes, and seconds. Declination is the angle between the celestial equator and the position of the star measured along the star's hour circle. It is measured in degrees, minutes, and seconds north or south of the celestial equator. By definition, the vernal equinox is located at right ascension 0h and declination 0°. Equatorial coordinates change with time due to the → precession of the Earth's → rotation axis.→ equatorial; → coordinate; → system. geocentric coordinate system   راژمان ِ هماراها‌ی ِ زمین‌مرکزی   râžmân-e hamârâhâ-ye zamin-markaziFr.: système de coordonnées géocentriques   A coordinate system which has as its origin the center of the Earth.→ geocentric; → coordinate; → system. geographic coordinate system   راژمان ِ هماراهای ِ زمین‌نگاریک   râžmân-e hamârâhâ-ye zaminnegârikFr.: système de coordonnées géographiques   A → ccordinate system on the surface of the Earth that defines every location by a set of numbers and letters, indicating the → latitude and → longitude.→ geographic; → coordinate; → system. horizon coordinate system   راژمان ِ هم‌آراهای ِ افقی   râžmân-e hamârâhâ-ye ofoqiFr.: coordonnées horizontales   The coordinate system based on the position of the observer. The horizontal plane is the fundamental plane and the coordinates are → altitude and → azimuth.→ horizon; → coordinate; → system. supergalactic coordinate system   راژمان ِ هماراهای ابرکهکشانی   râžmân-e hamârâhâ-ye abarkahkašâniFr.: système des coordonnées supergalactiques   A spherical → coordinate system in which the → equator is the → supergalactic plane. Supergalactic longitude, SGL, is measured → counterclockwise from direction l = 137.37 deg, b = 0 deg (between 0 and 360 deg). The zero point for supergalactic longitude is defined by the intersection of this plane with the → Galactic plane. In the → equatorial coordinate system (J2000) this is approximately 2.82 h, +59.5 deg. Supergalactic latitude, SGB, is measured from the supergalactic plane, positive northward and negative southward. The North Supergalactic Pole (SGB=90 deg) lies at galactic coordinates l = 47.37 deg, b = +6.32 degrees, corresponding to the equatorial coordinate system (J2000) 18.9 h, +15.7 deg.→ supergalactic; → coordinate; → system.