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The horizontal, or altitude-azimuth, system is based on the position of the observer on Earth, which revolves around its own axis once per sidereal day (23 hours, 56 minutes and 4.091 seconds) in relation to the star background. The positioning of a celestial object by the horizontal system varies with time, but is a useful coordinate system ...
Ecliptic latitude or celestial latitude (symbols: heliocentric b, geocentric β), measures the angular distance of an object from the ecliptic towards the north (positive) or south (negative) ecliptic pole. For example, the north ecliptic pole has a celestial latitude of +90°. Ecliptic latitude for "fixed stars" is not affected by precession.
The equatorial coordinate system on the celestial sphere. Star position is the apparent angular position of any given star in the sky, which seems fixed onto an arbitrary sphere centered on Earth. The location is defined by a pair of angular coordinates relative to the celestial equator: right ascension (α) and declination (δ).
The Sydney 'Star Camera' used in the Carte du Ciel project, original publication, 1892. The Carte du Ciel (French pronunciation: [kaʁt dy sjɛl]; literally, 'Map of the Sky') and the Astrographic Catalogue (or Astrographic Chart) were two distinct but connected components of a massive international astronomical project, initiated in the late 19th century, to catalogue and map the positions of ...
The celestial equator is currently inclined by about 23.44° to the ecliptic plane. The image shows the relations between Earth's axial tilt (or obliquity), rotation axis, and orbital plane. The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth.
The IERS has various components located in the United States, Europe and Australia.Among its other functions, the IERS is responsible for announcing leap seconds.. The Sub-bureau for Rapid Service and Predictions of Earth Orientation Parameters of the IERS, located at the United States Naval Observatory, monitors the Earth's rotation.
The International Celestial Reference System (ICRS) is the current standard celestial reference system adopted by the International Astronomical Union (IAU). Its origin is at the barycenter of the Solar System , with axes that are intended to "show no global rotation with respect to a set of distant extragalactic objects".
A series of shots show the rotation of Earth's axis relative to the south celestial pole. The Magellanic Clouds and the Southern Cross are clearly visible. Near the end of the video, the Moon rises and illuminates the scene. The south celestial pole over the Very Large Telescope [3] Locating the south celestial pole