Proper noun
ICRF (uncountable)
(astronomy) Initialism of International Celestial Reference Frame (the current standard celestial reference system adopted by the International Astronomical Union (IAU).)
The observations allow the determination of a measure of the Earth's angle with respect to the ICRF, called the Earth Rotation Angle (ERA, which serves as a modern replacement for Greenwich Mean Sidereal Time ). Source: Internet
The ICRF launched with nearly $23 million in initial donations, including $4 million from Governor Pritzker’s family and his foundation. Source: Internet