Conventional International Origin

The Conventional International Origin , abbreviated to CIO , is the central northern pole of rotation of the earth determined by a five-year measurement campaign from 1900 to 1905 .

The ongoing measurement of the current pole of the earth's rotation , which carries out a cyclical movement of a few meters radius - the pole fluctuation - and a slow, secular movement towards North America, refers to it .

The current pole coordinates are specified in angular seconds with respect to the CIO in a 2D Cartesian coordinate system, the x-axis of which was placed in the Greenwich zero meridian .

In addition to the 5 stations of the International Broad Service , numerous other observatories and institutes also took part in the campaign to determine the CIO . Today the International Earth Rotation Service (IERS) is responsible for monitoring the Earth's rotation .