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Right ascension is measured eastward up to 24 h along the celestial equator from the primary direction. Right ascension (abbreviated RA; symbol α) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the Earth. [1]
A-type star In the Harvard spectral classification system, a class of main-sequence star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times the mass of the Sun, and have surface temperatures of 7,600–10,000 kelvin.
Alternatively to right ascension, hour angle (abbreviated HA or LHA, local hour angle), a left-handed system, measures the angular distance of an object westward along the celestial equator from the observer's meridian to the hour circle passing through the object. Unlike right ascension, hour angle is always increasing with the rotation of Earth.
α - RA, right ascension, if the Greek letter does not appear, á letter will appear. δ - Dec, declination, if the Greek letter does not appear, ä letter will appear. P or P orb or T - orbital period; a - semi-major axis; b - semi-minor axis; q - periapsis, the minimum distance; Q - apoapsis, the maximum distance; e - eccentricity; i ...
Regulus is the brightest star in the constellation of Leo (right tip, below is bright Jupiter in 2004). Regulus is a multiple star system consisting of at least four stars. Regulus A is the dominant star, with a binary companion 177" distant that is thought to be physically related.
The change μ α, which must be multiplied by cosδ to become a component of the proper motion, is sometimes called the "proper motion in right ascension", and μ δ the "proper motion in declination". [11] If the proper motion in right ascension has been converted by cosδ, the result is designated μ α*.
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Right ascension (blue) and declination (green) as seen from outside the celestial sphere. The orbiting body direction cosine vector can be determined from the right ascension and declination (from Topocentric Equatorial Coordinate System) of the orbiting body from the observation points via: