High precision orbits for the international GPS service for geodynamics (IGS)

The objectives of the IGS include the regular computation of precise orbits for the GPS satellites, an essential prerequisite for geodetic, geophysical and navigation applications of GPS relying on accuracies at the level of metres to centimetres. This involves the deployment of advanced GPS receivers at a considerable number of globally distributed ground points, including several ESA tracking sites; the largely automated daily retrieval and processing of large amounts of remotely generated data; and regular independent comparisons of solutions computed by the various participating analysis centres, showing for example differences of typically 15 cm in solutions for all orbits in the GPS constellation. The paper reviews the IGS activities being carried out at ESOC in the context of the overall service.