More specifically, the ICRF is an inertial barycentric reference frame whose axes are defined by the measured positions of extragalactic sources (mainly quasars) observed using very-long-baseline interferometry while the Gaia -CRF is an inertial barycentric reference frame defined by optically measured positions of extragalactic sources by the G...

The International Celestial Reference Frame (ICRF) is the realization of the International Celestial Reference System (ICRS). It comprises a catalog of precise equatorial coordinates of extragalactic radio sources observed by Very Long Baseline Interferometry ( VLBI ) .

The ICRS is materialized by precise equatorial coordinates of extragalactic radio sources observed in Very Long Baseline Interferometry (VLBI) programmes. This first realization of the ICRF, although officially adopted in 1998, was elaborated by the IAU Working Group on Reference Frame (WGRF) during 1995.

2020年10月26日 · This new realization, referred to as ICRF3, is based on nearly 40 years of data acquired by very long baseline interferometry. The ICRF3 includes positions at 8.4 GHz for 4536 sources, supplemented with positions at 24 GHz for 824 sources and at 32 GHz for 678 sources, for a total of 4588 sources.

ICRF = realization of the ICRS . through a sufficient number of coordinate pairs (𝛼𝛼,𝛿𝛿) of extragalactic radio sources determined by geodetic / astrometric analysis of VLBI observations • An . extragalactic radio source . is associated with a shock region of a relativistic jet of an active galaxy, the shock region is not entirely ...

Derived using data from August 1979 through March 2009, it is a great improvement over the original ICRF with 3414 extragalactic radio source positions, a noise floor of 40 microarcsec, and axis stability of 10 microarcsec. Significant refinements were made in the selection of defining sources, modeling, and the integration of CRF, TRF, and EOP.

The orientation of the ICRF axes was deemed to be accurate to 20 microarcseconds (μas) while source coordinates had a noise floor of 250 μas. As a consequence of the ICRS definition, all source positions in the ICRF were independent of epoch.

2022年7月7日 · We briefly review the history of the transition from the Fundamental Katalog 5 (FK5) optical frame to VLBI-based frames with attention to each of the three generations: ICRF-1, ICRF-2, and...

2021年4月30日 · The new frame includes positions at 8.4 GHz for 4536 extragalactic sources. Of these, 303 sources, uniformly distributed on the sky, are identified as “defining sources” and as such serve to define the axes of the frame. Positions at 8.4 GHz are supplemented with positions at 24 GHz for 824 sources and at 32 GHz for 678 sources.

2020年10月26日 · This new realization, referred to as ICRF3, is based on nearly 40 years of data acquired by very long baseline interferometry. The ICRF3 includes positions at 8.4 GHz for 4536 sources, supplemented...