Overview

The EPN is a European network of continuously operating GNSS reference stations. Its coordination and daily operations are managed by the EPN Central Bureau (EPN CB), hosted at the Royal Observatory of Belgium.

GNSS Tracking Network

• Stations equipped with geodetic GNSS receivers on stable monuments.
• Operated by agencies, universities, or research centres under EPN guidelines.
• Adheres to standards for data formatting, metadata, and communication protocols.
• New station proposals via the station integration procedure.

M³G – Metadata Management and Distribution System

Authorized agencies (called "Metadata Maintainers") use M³G to:

• Upload, validate, and publish station metadata, including:
  • IGS-style site logs
  • RINEX data licenses and usage terms
  • DOI assignments and citation information
• Ensure metadata compliance across networks such as EPN and IGS.

M³G improves interoperability and findability by consolidating station metadata in a single centralized system.

Station Owners

Each EPN station is owned by a local institution, listed as the “Responsible Agency” in the station site log. The Station Owner ensures proper operation and EPN compliance, and remains fully responsible even if tasks (such as metadata maintenance) can be delegated to an external agency.

Station Owners are responsible for:

• Validating GNSS observation data at the source.
• Converting raw receiver data to the standardized Receiver Independent Exchange Format (RINEX)
• Compressing RINEX files and, where applicable, generating real-time data streams.
• Uploading data to the appropriate EPN Data Centres and Broadcasters via the Internet.
• Maintaining and updating all station metadata, including:
  • The IGS-compliant station site log
  • Data licensing information
  • Contact details and station documentation

The role of the Station Owner is critical for maintaining the reliability of the EPN, ensuring that each station contributes high-quality data to the EPN.

Metadata Maintainers

Metadata Maintainers are authorized agencies responsible for keeping station metadata accurate and up to date within M³G. This role is typically held by the Station Owner, but when delegated to an external agency, that agency is granted a user account in M³G to manage the metadata directly. The tasks of the Metadata Maintainers include:

• Creating and regularly updating IGS site logs for each station.
• Documenting all equipment changes, firmware updates, and local site conditions.
• Ensuring alignment with EPN metadata standards and FAIR principles.
• Coordinating with the EPN Central Bureau to validate submitted metadata.

Accurate metadata is essential for ensuring traceability, reproducibility, and high-quality geodetic products.

Data Centres

EPN Data Centres provide access to EPN station data and/or EPN products:

• Local Data Centres (LDCs): Collect and distribute station data of a local or national network.
• Regional Data Centres (RDCs): Provide access to the data from all EPN stations and relay them to the IGS
• High-Rate Data Center: Provides 1 Hz data.
• Historical Data Center: Provides a full data archive.

In addition, broadcasters provide access to real-time 1 Hz data streams in the RTCM format using Ntrip.

Analysis Centres

Analysis Centres process, according to well-defined standards, the RINEX data from agreed-upon EPN subnetworks and provide estimates of daily/weekly station positions and hourly troposheric zenith path delays. Combined solutions feed EPN’s official coordinate and troposphere products, essential for ETRS89/ITRS reference frame maintenance and climate research.

Data Products, Tools & Services

• Station coordinate and velocity updates for ETRF/ITRF.
• Tropospheric zenith path delays.
• ETRS89 satellite orbit and clock correction streams.
• OpenAPI-compliant REST API for programmatic access to metadata, data, information files, and products.
• Transformation for ETRS89 ↔ ITRS.
• Documentation & Guidelines.

Governance & Contact

The EPN Central Bureau, led by Dr. Carine Bruyninx, is supported by:

• EPN Coordination Group: Oversees operations and policies.
• EUREF Governing Board: Sets strategic direction and endorses updates.

Contact:
Royal Observatory of Belgium
av. Circulaire 3, 1180 Brussels, Belgium
Email: epncb@oma.be
X: @be_GNSS