The GCRF frame is essentially the ICRF frame, but with a slightly different relativistic time scale. The JPL ephemerides (the underlying basis of JPL Horizons and JPL's SPICE system) treat the J2000 frame and the ICRF frames as equivalent.

The geocentric celestial reference system (GCRS), also created by the IAU in 2000, is a similar standard coordinate system used to specify the location and motions of near-Earth objects, such as satellites. [1] Its center of coordinates is the center of mass of the Earth.

A reference frame is an ordered set of three mutually orthogonal (possibly time dependent) unit-length direction vectors, coupled with a location called the frame’s “center” or “origin.”

The International Celestial Reference Frame (ICRF) is a realization of the International Celestial Reference System using reference celestial sources observed at radio wavelengths.

the definition (within the GR framework) of the celestial and terrestrial space-time reference systems (GCRS, GTRS, ITRS) and the transformation between them in the PN approximation,

A coordinate or frame in the Geocentric Celestial Reference System (GCRS). GCRS is distinct form ICRS mainly in that it is relative to the Earth’s center-of-mass rather than the solar system Barycenter. That means this frame includes the effects of aberration (unlike ICRS).

Other terrestrial reference frames are the World Geodetic System 84 (WGS-84), which is applied for GPS, the Parametry Zemli 1990 (Parameters of the Earth 1990) (PZ-90) for GLONASS, or the Galileo Terrestrial Reference Frame (GTRF) for Galileo system.

Jul 24, 2017 · A kinematically non-rotating reference frame is one in which the remote stars, or more recently, the remote quasars, do not appear to be rotating with respect to the origin of the frame of reference.

The ICRS, BCRS and GCRS, ITRS: astronomical reference-systems and frames in the framework of Relativity, problems of nomenclature Michael Soffel & Sergei Klioner

Celestial Reference System (CRS) has its origin in the Earth's centre of mass or Geocentre, its fundamental plane is the mean Equator plane (containing the Geocentre) of the epoch J2000.0, and the principal axis x is pointing to the mean Vernal equinox of epoch J2000.0. The three axis defining this coordinate are shown in Figure 1.