ascensiondeclination

Ascensiondeclination is not a standard term in astronomy. It is sometimes used informally or in fictional contexts to refer to the two coordinates that specify a position on the celestial sphere within the equatorial coordinate system: right ascension and declination. In formal astronomy, the pair is known as right ascension (RA) and declination (Dec), and “ascension” is not part of the official nomenclature.

Right ascension measures how far east along the celestial equator an object lies, typically expressed in hours, minutes, and seconds. Declination measures the angular distance north or south of the celestial equator, expressed in degrees, arcminutes, and arcseconds. These two components together locate objects on the sky much like longitude and latitude locate places on Earth. RA is usually measured from the vernal equinox and increases eastward; Dec is bounded between +90 and −90 degrees.

Coordinates are defined for a specific epoch because celestial objects move over time due to precession and proper motion. The most common reference epoch in modern astronomy is J2000.0. Observers often convert between coordinate systems (for example, to galactic or ecliptic coordinates) or adjust for epoch differences when planning observations.

In practice, astronomers rely on RA and Dec rather than a single combined term. The occasional use of ascensiondeclination may appear in educational or fictional writing as a shorthand for the two-coordinate description, but it does not replace the standard framework of right ascension and declination.