Participation in international geodetic observations

GSI participates in multilateral joint campaigns and observations.

International VLBI Service for Geodesy and Astrometry (IVS)

What is IVS?

IVS is an international collaborative initiative which was established by International Association of Geodesy (IAG) in 1999 with the purpose of promoting international observation campaigns and technical development on VLBI. Under the cooperation between member organizations, IVS is operating and maintaining global VLBI observation network, analyzing the observation data and providing various information on motion of the earth such as precise coordinates of the stations and the earth orientation parameters.
image of network

International VLBI Observation Network

GSI’s contribution

GSI has been participating IVS from the beginning of the service as a part of VLBI observation network, one of correlators and one of analysis centers, and contributing to development of global geodetic reference frame and monitoring the earth rotation. In order to enhance regional cooperation in Asia and Oceania, IVS established a subgroup of IVS, Asia-Oceania VLBI Group for Geodesy and Astrometry (AOV) in 2014. GSI played a leading role on the establishment of AOV and is actively involved in AOV by carrying out regional observations.

VLBI stations of GSI

GSI is operating a VLBI station in Ishioka, Japan

Ishioka station

VLBI antenna
of Ishioka station

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International GNSS Service (IGS)

What is IGS?

IGS is an international collaborative initiative which was established by IAG in 1994 with the purpose of sharing GNSS observation data and providing GNSS related products such as satellite orbit information. Under the cooperation between member organizations, IGS is operating and maintaining global GNSS observation network, sharing and analyzing GNSS data and providing various GNSS related information such as precise satellite orbit information which is essential for precise GNSS positioning. In order to support its activity, GSI has been participating in IGS from the establishment in 1994.

GSI’s contribution

  • GSI generates GNSS satellite precise ephemeris and routinely provides the products to IGS as one of IGS Analysis Centers (ACs).
  • GSI operates 8 IGS stations and routinely provides the data to IGS.
  • GSI analyzes GNSS data observed at the IGS stations of Japan and surrounding areas as one of IGS Regional Network Associated Analysis Centers (RNAACs).
  • GSI participates in Working Group and Pilot Projects of IGS.
    • MGEX (Multi-GNSS pilot project)
    • RTS (Real-time Service)
    • TIGA (Tide Gauge) Working Group
    • GNSS Performance Monitoring IGMA-IGS Joint Trial Project

Operation of the IGS Analysis Center

GSI, in collaboration with the Japan Aerospace Exploration Agency (JAXA), has been participating in the IGS Analysis Centers (ACs) since December 2023. ACs are IGS-accredited organizations in charge of calculating precise ephemeris for GNSS satellites. The IGS products, widely used as international standards, are calculated by the IGS integrating a total of 13 AC products. As one of the ACs, GSI and JAXA contribute to the generation of IGS products.
Our products are available at the following page with registration:
JGX products providing service
Precise Ephemeris


IGS stations of GSI

GSI is currently operating 8 IGS stations.
8 IGS stations

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