International Celestial 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

• Good narrative description
• Overview of ICRS and ICRF
• IERS Conventions 2003 (defines ICRS and other related standards)
• General information on the ICRS
• ICRS Product Center