Bureau International de l'Heure

Overview
The Bureau International de l'Heure (BIH) is

"[t]he organization responsible, by international agreement, for coordinating the measurements of time by national observatories and for providing an internationally acceptable and common time. It is also responsible for maintaining the international atomic second. As part of its function, it calculates the position of the Earth's axis of rotation and changes in the Earth's rate of rotation."