International Celestial Reference System

(astronomy) A system that is realized by the International Celestial Reference Frame, made up from the positions of extragalactic radio sources, and that encompasses the standard reference frames, the transformations between them, and all the constants and motions involved, as well as the time scales specified for the reference frames and origins involved. It was adopted by the International Astronomical Union in 1994 as the fundamental reference system.

The International Celestial Reference System (ICRS) is the current standard celestial reference system adopted by the International Astronomical Union (IAU). Its origin is at the barycenter of the solar system, with axes that are intended to be "fixed" with respect to space. ICRS co-ordinates are approximately the same as equatorial co-ordinates: the mean pole at J2000.0 in the ICRS lies at 17.3±0.2 mas in the direction 12 h and 5.1±0.2 mas in the direction 18 h. The mean equinox of J2000.0 is shifted from the ICRS right ascension origin by 78±10 mas (direct rotation around the polar axis).

See also

• International Celestial Reference Frame
• International Terrestrial Reference System
• Astronomy
• Astrometry

References

• Very good ICRS and ICRF overview
• IERS Conventions 2003 (defines ICRS and other related standards)
• General information on the ICRS
• ICRS Product Center

This astronomy-related article is a stub. You can help Wikipedia by expanding it.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)