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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] When paired with declination, these astronomical coordinates specify the location of a point on the ...
In this case, the longitude is also called the right ascension of the ascending node (RAAN). The angle is measured eastwards (or, as seen from the north, counterclockwise) from the FPA to the node. [2] [3] An alternative is the local time of the ascending node (LTAN), based on the local mean time at which the spacecraft crosses the equator.
Model of the equatorial coordinate system. Declination (vertical arcs, degrees) and hour angle (horizontal arcs, hours) is shown. For hour angle, right ascension (horizontal arcs, degrees) can be used as an alternative. The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects.
Setting circles consist of two graduated disks attached to the axes – right ascension (RA) and declination (DEC) – of an equatorial mount. [1] The RA disk is graduated into hours, minutes, and seconds. The DEC disk is graduated into degrees, arcminutes, and arcseconds. Since the RA coordinates are fixed onto the celestial sphere, the RA ...
It was incorporated in Pennsylvania on September 17, 1997, as Right Ascension, Inc. With $6,000 in start-up funds, the company became a full-time occupation for the two partners. The site's design aimed for ease of navigation, and allowed customers to edit every aspect of their orders prior to shipment, and were the first to offer pre-ordering ...
Hour angle. The hour angle is indicated by an orange arrow on the celestial equator plane. The arrow ends at the hour circle of an orange dot indicating the apparent place of an astronomical object on the celestial sphere. In astronomy and celestial navigation, the hour angle is the dihedral angle between the meridian plane (containing Earth's ...
This is located within the constellation of Hercules, around coordinates right ascension 18 h 00 m and declination 30° 00′. [5] The north pole of the supergalactic coordinate system is located within this constellation at right ascension 18 h 55 m 01 s and declination +15° 42′ 32″.
IAU designated constellations in equirectangular projection (epoch B1875.0) In contemporary astronomy, 88 constellations are recognized by the International Astronomical Union (IAU). [ 1] Each constellation is a region of the sky bordered by arcs of right ascension and declination, together covering the entire celestial sphere.