TIO – Terrestrial Intermediate Origin

The Terrestrial Intermediate Origin (TIO) is a reference point on the Earth’s equator used to define Earth’s rotation angle relative to the International Terrestrial Reference Frame (ITRF). It complements the Celestial Intermediate Origin (CIO) and Celestial Intermediate Pole (CIP) in modern Earth rotation modeling. The TIO ensures precise determination of Earth rotation and supports accurate satellite navigation, geodesy, and timekeeping.

More Info: https://geodesy.science/item/earth-orientation-parameter