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International Celestial Reference Frame (ICFR)

The International Celestial Reference Frame (ICFR) is an extragalactic reference frame adopted in 1998 by the International Astronomical Union. It is defined with respect to 618 remote extragalactic radio sources (mostly quasars) whose positions have been accurately determined using very long baseline interferometry. Positions of stars in our galaxy are now tied to the ICFR, as are measurements of Earth's orientation.

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