International GNSS Service (IGS)

The CDDIS serves as a Global Data Center for the IGS, supporting the archive and distribution of data from the global network of permanent receivers and the IGS products derived from these data.


The mission of the International GNSS Service (IGS) is to provide the highest quality GNSS data, products, and services in support of the terrestrial reference frame, Earth observations and research, positioning, navigation, and timing (PNT), and other applications that benefit the scientific community and society.


The IGS was established by the International Association of Geodesy (IAG) in 1993 and began formal operation in January 1994. The IGS is a federation of over 200 worldwide national agencies, universities, and research institutions in more than ninety countries. The IGS provides GNSS orbits, tracking data, and other data products in support of geodetic and geophysical research. The IGS also supports a variety of governmental and commercial activities and develops international GNSS data standards and specificiations.

Data and Products

The IGS collects, archives, and distributes GNSS (operationally GPS and GLONASS ) observation data sets of sufficient accuracy to meet the objectives of a wide range of scientific and engineering applications and studies. The IGS has developed a worldwide system, comprising satellite tracking stations, data centers, and analysis centers, to put high-quality GNSS data on-line within hours and data products on-line within days and weeks of observations.

The GNSS data sets are used to generate the following products:

  • GNSS satellite ephemerides
  • Earth rotation parameters
  • Global tracking station coordinates and velocities
  • GNSS satellite and IGS tracking station clock information
  • Zenith tropospheric path delay estimates
  • Global ionospheric maps

These products support Earth science analyses and other efforts, such as:

  • Improving and extending the International Terrestrial Reference Frame (ITRF) maintained by the International Earth Rotation and Reference Systems Service (IERS)
  • Coordinated Universal Time (UTC)
  • Measuring and monitoring the length of day
  • Monitoring deformation of the Earth
  • Monitoring Earth rotation
  • Monitoring the composition and state of the troposphere and ionosphere
  • Determining orbits of scientific satellites
  • Comparison of clocks
  • Other diverse applications

GPS orbits provided through the IGS are on the order of 2-5 cm, the highest precision in the world; precise positions are on the order of 5 mm for over 450 worldwide reference stations. All products are mutually consistent in the IGS realization of the ITRF.

The IGS continues to develop new applications and products in working groups, pilot projects, and dedicated services.