The right ascension of a point on the celestial sphere is the angle measured eastward along the celestial equator from the vernal equinox to the meridian containing the point. Follow edited Nov 29 '13 at 21:55. fundamental-astronomy ascension declination. The angle from the vernal equinox eastward to the foot of that hour circle is the star's right ascension. Credit: NASA Follow @heavensabovecom: Developed and maintained by Chris Peat, Heavens-Above GmbH. 147 1 1 gold badge 2 2 silver badges 8 8 bronze badges. This equation computes the right ascension of the ascending (R.A.A.N) node, Omega, of an orbit from the inputs: n_x - the x-component of the nodal vector; n - the nodal vector's magnitude; The right ascension of the ascending node is the angle from a reference direction, called the origin of longitude, to the direction of the ascending node. For Right Ascension, astronomers always use the convention of Hours:Minutes:Seconds. If you have a question about what an entry box is asking for, … Unlike the Nautical Almanac and ICE (Interactive Computer Ephemeris), MICA only provides the Right Ascension… Share. One hour of right ascension (1 h) is 15°. Right ascension 22 h 1 m 21 s: Declination -12° 6' 29" Range (AU) 0.9880891: Constellation Aquarius: Position of the Sun Latest image of the Sun from the SDO Satellite. Right ascension and declination and are used as longitude and latitude respectively, to locate/specify the direction to celestial objects. Geocentric sun right ascension [degrees] Geocentric sun declination [degrees] Observer hour angle [degrees] Sun equatorial horizontal parallax [degrees] Sun right ascension parallax [degrees] Topocentric sun declination [degrees] Topocentric sun right ascension [degrees] Topocentric local hour angle [degrees] For example, if the right ascension is 2 hours, 30 minutes and 45 seconds, then this time in decimal form is 2 + 30/60 + 45/3600 = 2.5125. Purpose of use simulation of the starry night Comment/Request I need to simulate stary night for simulation of a star sensor. Peter Jansson. Improve this question. Right Ascension (RA) Right Ascension is measured in hours (h), minutes (m) and seconds (s) and is similar to longitude on Earth. As the Earth rotates, stars appear to rise in the East and set in the West just like the Sun. … Proper motion is ignored. There is one oddity in right ascension: the unit used to report the angle. Description: This calculator has been developed primarily to extract the Greenwich Hour Angle, GHA, of a celestial body from MICA (Multiyear Interactive Computer Almanac) in a convenient way, but it can be used in combination with other almanac software or printed almanacs as well. Right ascensions are always recorded in terms of hours, minutes, and seconds. For this purpose, I utilize HIPPARCOS catalog for stars, but in order to complete my simulation, I need the position of the sun, moon and the planets of the solar system in right ascension coordinate system (right acension and declination). There are 24 hours of RA around a circle in the sky, because it takes 24 hours for the Sun to move all the way from sunrise to the next sunrise. How can I calculate the right ascension and declination? Right Ascension 06:45:09, Declination -16:42:58 meaning the Right Ascension is 6 hours, 45 minutes, 09 seconds Astrometric Position Calculator Use this page to compute accurate equatorial coordinates (Right Ascension and Declination) for an object in your image --- an asteroid or comet, for example. Right Ascension hours can be entered in a variety of formats. 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