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International VLBI Service for Geodesy and Astrometry (IVS)

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


The charter of the International VLBI Service for Geodesy and Astrometry (IVS)) is to provide a service which supports geodetic and astrometric work on reference systems, Earth science research, and operational activities. The goals of the IVS are:

  • To provide a service to support geodetic, geophysical and astrometric research and operational activities.
  • To interact with the community of users of VLBI products and to integrate VLBI into a global Earth observing system.
  • To promote research and development activities in all aspects of the geodetic and astrometric VLBI technique.


The IVS is an international collaboration of organizations which operate or support Very Long Baseline Interferometry (VLBI) components. IVS is a Service of the International Association of Geodesy (IAG) and of the International Astronomical Union (IAU).

IVS fulfills its charter through the following objectives:

  1. Foster and carry out VLBI programs. This is accomplished through close coordination of the participating organizations to provide high-quality VLBI data and products.
  2. Promote research and development activities in all aspects of the geodetic and astrometric VLBI technique.
  3. Advance the education and training of VLBI participants through workshops, reports, and other means.
  4. Support the integration of new components into IVS.
  5. Interact with the community of users of VLBI products.

IVS represents VLBI in the Global Geodetic Observing System (GGOS) of the IAG and interacts closely with the International Earth Rotation and Reference Systems Service (IERS).

Data and Products

VLBI data products contribute uniquely to these important activities:

  • Defining and maintaining the celestial reference frame,
  • Monitoring universal time (UT1),
  • Monitoring the coordinates of the celestial pole (nutation and precession).

These results are the foundation of many scientific and practical applications requiring the use of an accurate quasi-inertial reference frame, such as high-precision positioning, navigation, and timing. In addition IVS provides a variety of VLBI products with differing applications, timeliness, detail, and temporal resolution, such as:

  • All components of Earth orientation parameters,
  • Terrestrial reference frame,
  • Baseline lengths,
  • Tropospheric parameters.

All VLBI data and products are publicly available in appropriate formats from IVS Data Centers like the CDDIS.

From: IVS web site