CIP – Celestial Intermediate Pole

The Celestial Intermediate Pole (CIP) defines the instantaneous rotation axis of the Earth in space, accounting for precession, nutation, and other small variations. It is a key component of the Earth Orientation Parameters (EOP) that link the International Celestial Reference Frame (ICRF) with the International Terrestrial Reference Frame (ITRF). The CIP, together with the Celestial Intermediate Origin (CIO), enables precise measurement of Earth rotation and supports accurate satellite navigation, positioning, and timekeeping.

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