The purpose of the IRIS-S sessions is to continue the series of measurements for the determination of earth rotation parameters. IRIS-S experiments are set up to provide all earth orientation parameters (UT1, polar motion, and nutation), baseline components and positions of extragalactic radio sources. With the addition of Fairbanks this network produced excellent EOP results. This network with long north-south and east-west baselines as well as the wideband capability provides a good EOP determination even with the inclusion of the O'Higgins antenna.

Network

The standard configuration of the monthly observed IRIS-S (South) experiments consists of four stations. One station in the United States (Westford,Ma), one station in South Africa (HartRAO), one radio telescope in Europe (Wettzell,Germany) and one radio telescope in South America (Fortaleza,Brasil). Since January 1997 the network is augmented by station Fairbanks (Alaska). During the O'Higgins occupations two more stations of the southern hemispere are added to this network. With O'Higgins and Hobart(Tasmania) we will have seven participate station in this network.