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Therefore, the horizontal coordinate system is sometimes called the az/el system, [1] the alt/az system, or the alt-azimuth system, among others. In an altazimuth mount of a telescope , the instrument's two axes follow altitude and azimuth.
Horizontal (also called alt-az or el-az) Observer Horizon: Zenith, nadir: Altitude (a) or elevation Azimuth (A) North or south point of horizon Equatorial: Center of the Earth (geocentric), or Sun (heliocentric) Celestial equator: Celestial poles: Declination (δ) Right ascension (α) or hour angle (h) March equinox: Ecliptic: Ecliptic ...
RA radio altitude or radar altimeter: RA resolution advisory In the context of TCAS: RAAS Runway Awareness and Advisory System: RAAS remote airport advisory service Rad Alt Radio Altitude Radar: RAdio Detection And Ranging RAI Radio altimeter indicator RAIM Receiver Autonomous Integrity Monitoring: Or: remote autonomous integrity monitoring RALT
Altitude-azimuth, alt-azimuth, or alt-az may refer to: Horizontal coordinate system, or altitude-azimuth coordinates; Altazimuth mount, a two-axis telescope mount
In the largest telescopes, the mass and cost of an equatorial mount is prohibitive and they have been superseded by computer-controlled altazimuth mounts. [5] The simple structure of an altazimuth mount allows significant cost reductions, in spite of the additional cost associated with the more complex tracking and image-orienting mechanisms. [6]
Coordinate conversion is composed of a number of different types of conversion: format change of geographic coordinates, conversion of coordinate systems, or transformation to different geodetic datums. Geographic coordinate conversion has applications in cartography, surveying, navigation and geographic information systems.
The right ascension symbol α, (lower case "alpha", abbreviated RA) measures the angular distance of an object eastward along the celestial equator from the March equinox to the hour circle passing through the object. The March equinox point is one of the two points where the ecliptic intersects the celestial equator.
Alternatively, the conversion can be considered as two sequential rectangular to polar conversions: the first in the Cartesian xy plane from (x, y) to (R, φ), where R is the projection of r onto the xy-plane, and the second in the Cartesian zR-plane from (z, R) to (r, θ).