The foundation of the IGS is a global network of over 400 permanent, continuously operating, geodetic quality stations tracking GPS, GLONASS, Galileo, BeiDou, QZSS, and SBAS.
Station data is archived at four IGS Global Data Centers and multiple Regional Data Centers. Analysis Centers regularly process the data and contribute products to the Analysis Center Coordinator, who produces the official IGS combined products. The Central Bureau is responsible for day-to-day management of the IGS, following policies set by the IGS International Governing Board.
IGS and the International Terrestrial Reference Frame (ITRF)
The IGS contributes to, extends, and densifies the International Terrestrial Reference Frame (ITRF). The ITRF provides an accurate and consistent frame, or datum, for referencing positions at different times and in different locations around the world. The IGS realization of ITRF, which extends the number of stations significantly, makes the reference frame easily accessible.
In particular, the accuracies of IGS products are sufficient for the improvement and extension of the International Terrestrial Reference Frame (ITRF), the monitoring of solid Earth deformations, the monitoring of Earth rotation and variations in the liquid Earth (sea level, ice-sheets, etc.), for scientific satellite orbit determinations, ionosphere monitoring, and recovery of precipitable water vapor measurements.