GNSS Ultra-Rapid Combined Earth Rotation Parameter (ERP) Product

doi: 10.5067/GNSS/gnss_igsuerp_001

Data Center Citation

Noll, Carey E., The Crustal Dynamics Data Information System: A resource to support scientific analysis using space geodesy, Advances in Space Research, Volume 45, Issue 12, 15 June 2010, Pages 1421-1440, ISSN 0273-1177,

Data Citation

International GNSS Service, GNSS Ultra-Rapid Combined Earth Rotation Parameter (ERP) Product, Greenbelt, MD, USA: NASA Crustal Dynamics Data Information System (CDDIS), Accessed [[enter user data access date]] at doi:10.5067/GNSS/gnss_igsuerp_001.

Other standard citation formats may be used for this data set and can be found at the DOI Citation Formatter website.

More information about CDDIS data citations and acknowledgments is available.


  • Name: GNSS Ultra-Rapid Combined Earth Rotation Parameter (ERP) Product available from the Crustal Dynamics Data Information System (CDDIS)
  • Format: IGS ERP format, UNIX compressed ASCII
  • Spatial Coverage: 90.0 to -90.0, 180.0 to -180.0
  • Temporal Coverage: 2000-09-17 to present
  • Temporal Resolution: Four times/day
  • File Size: 10 Kbytes/day
  • Platforms: GPS, GLONASS


The IGS ultra-rapid products can be used to determine precise coordinates of the observing stations, gravity field parameters, and Earth orientation parameters. The IGS derived products are essential for Earth science research; multi-disciplinary positioning, navigation, and timing (PNT) applications; and education. The IGS ultra-rapid products are available for near-real time use.

This derived product set consists of Global Navigation Satellite System Ultra-Rapid Earth Rotation Product (ERP) from the NASA Crustal Dynamics Data Information System (CDDIS). GNSS satellites provide autonomous geo-spatial positioning with global coverage. GNSS data sets from ground receivers at the CDDIS consist primarily of the data from the U.S. Global Positioning System (GPS) and the Russian GLObal NAvigation Satellite System (GLONASS). Since 2011, the CDDIS GNSS archive includes data from other GNSS (Europe’s Galileo, China’s Beidou, Japan’s Quasi-Zenith Satellite System/QZSS, the Indian Regional Navigation Satellite System/IRNSS, and worldwide Satellite Based Augmentation Systems/SBASs), which are similar to the U.S. GPS in terms of the satellite constellation, orbits, and signal structure. Analysis Centers (ACs) of the International GNSS Service (IGS) retrieve GNSS data on regular schedules to produce GNSS Earth Rotation products. The IGS Analysis Center Coordinator (ACC) uses these individual AC solutions to generate the official IGS ultra-rapid combined ERP products. The ultra-rapid ERP combination is a sub-daily solution, released four times per day, at 03:00, 09:00, 15:00, and 21:00 UTC (prior to GPS week 1267 they were released twice daily). IGS ultra-rapid ERP files are to be used with the IGS ultra-rapid orbit solution files. All ERP solution files utilize the IGS ERP format.

Data Access

GNSS Ultra-Rapid Combined Earth Rotation Parameter (ERP) Products (GPS and GPS+GLONASS solutions) are online:

Append the following directory and file names to the starting directory:


as described in the table below.

Code Meaning
Dday of week (0-6, 7 indicates weekly)
HH hour of day (00, 06, 12, 18)
.Z UNIX compressed file