Reference frame
The International Celestial Reference Frame (ICRF3)
The practical realisation of the International Celestial Reference System — a catalogue of precise positions for several thousand extragalactic radio sources, mostly quasars, measured by very-long-baseline interferometry. Its third realisation, ICRF3, was adopted in 2018; because quasars are effectively fixed, it provides the quasi-inertial grid to which optical frames such as Gaia's are aligned.
Highlights
- ›Quasar positions by VLBI — the fixed grid behind ICRS
Related systems & concepts
Across the reference systems
Knowledge connections
- Associated withThe International Celestial Reference System
- Associated withGaia
- Associated withInternational Earth Rotation and Reference Systems Service (IERS)
- Associated withSpace Astrometry
- Associated withInternational Earth Rotation and Reference Systems Service (IERS)
Sources
The primary and reference sources this topic draws on.
- IAUInternational Astronomical Union
Official naming, definitions, constellation boundaries, and astronomical nomenclature.