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IGS Products

The IGS collects, archives, and distributes GPS and GLONASS observation data sets of sufficient accuracy to meet the objectives of a wide range of scientific and engineering applications and studies. These data sets are analyzed and combined to form the IGS products shown in the table below.

IGS products support scientific activities such as improving and extending the International Terrestrial Reference Frame (ITRF) maintained by the International Earth Rotation and Reference Systems Service (IERS), monitoring deformations of the solid Earth and variations in the liquid Earth (sea level, ice sheets, etc.) and in Earth rotation, determining orbits of scientific satellites, and monitoring the troposphere and ionosphere.

IGS Product Table [GPS Broadcast values included for comparison] -- updated for 2009!
Accuracy Latency Updates Sample Interval Archive locations
GPS Satellite Ephemerides/
Satellite & Station Clocks
Broadcast orbits ~100 cm real time -- daily CDDIS(US-MD)
SOPAC(US-CA)
IGN(FR)
Sat. clocks ~5 ns    RMS
~2.5 ns SDev
Ultra-Rapid (predicted half) orbits ~5 cm real time at 03, 09, 15, 21 UTC 15 min CDDIS(US-MD)
IGS CB(US-CA)
SOPAC(US-CA)
IGN(FR)
KASI (KOREA)
Sat. clocks ~3 ns    RMS
~1.5 ns SDev
Ultra-Rapid (observed half) orbits ~3 cm 3 - 9 hours at 03, 09, 15, 21 UTC 15 min CDDIS(US-MD)
IGS CB(US-CA)
SOPAC(US-CA)
IGN(FR)
KASI (KOREA)
Sat. clocks ~150 ps RMS
~50 ps   SDev
Rapid orbits ~2.5 cm 17 - 41 hours at 17 UTC daily 15 min CDDIS(US-MD)
IGS CB(US-CA)
SOPAC(US-CA)
IGN(FR)
KASI (KOREA)
Sat. & Stn. clocks ~75 ps RMS
~25 ps SDev
5 min
Final orbits ~2.5 cm 12 - 18 days every Thursday 15 min CDDIS(US-MD)
IGS CB(US-CA)
SOPAC(US-CA)
IGN(FR)
KASI (KOREA)
Sat. & Stn. clocks ~75 ps RMS
~20 ps SDev
Sat.: 30s
Stn.: 5 min
Note 1: Orbit accuracies are 1D mean RMS values over the three XYZ geocentric components. IGS accuracy limits, except for predicted orbits, are based on comparisons with independent laser ranging results and discontinuities between consecutive days. The precision is better.
Note 2: The accuracy (neglecting any contributions from internal instrumental delays, which must be calibrated separately) of all clocks is expressed relative to the IGS timescale, which is linearly aligned to GPS time in one-day segments. The standard deviation (SDev) values are computed by removing a separate bias for each satellite and station clock, whereas this is not done for the RMS values.
GLONASS Satellite Ephemerides
Final ~3 cm 12 - 18 days every Thursday 15 min CDDIS(US-MD)
IGN(FR)
Geocentric Coordinates of IGS Tracking Stations (>250 sites)
Final positions horizontal 3 mm 11 - 17 days every Wednesday weekly CDDIS(US-MD)
SOPAC(US-CA)
IGN(FR)
vertical 6 mm
Final velocities horizontal 2 mm/yr 11 - 17 days every Wednesday weekly CDDIS(US-MD)
SOPAC(US-CA)
IGN(FR)
vertical 3 mm/yr
Earth Rotation Parameters:
Polar Motion (PM)
Polar Motion Rates (PM rate)
Length-of-day (LOD)
Ultra-Rapid (predicted half) PM ~200 µas real time at 03, 09, 15, 21 UTC daily integrations at 00, 06 12, 18 UTC CDDIS(US-MD)
IGS CB(US-CA)
SOPAC(US-CA)
IGN(FR)
KASI (KOREA)
PM rate ~300 µas/day
LOD ~50 µs
Ultra-Rapid (observed half) PM ~50 µas 3 - 9 hours at 03, 09, 15, 21 UTC daily integrations at 00, 06, 12, 18 UTC CDDIS(US-MD)
IGS CB(US-CA)
SOPAC(US-CA)
IGN(FR)
KASI (KOREA)
PM rate ~250 µas/day
LOD ~10 µs
Rapid PM ~40 µas 17 - 41 hours at 17 UTC daily daily integrations at 12 UTC CDDIS(US-MD)
IGS CB(US-CA)
SOPAC(US-CA)
IGN(FR)
KASI (KOREA)
PM rate ~200 µas/day
LOD ~10 µs
Final PM ~30 µas 11 - 17 days every Wednesday daily integrations at 12 UTC CDDIS(US-MD)
IGS CB(US-CA)
SOPAC(US-CA)
IGN(FR)
KASI (KOREA)
PM rate ~150 µas/day
LOD ~10 µs
Note 1: 100 µas = 3.1 mm of equatorial rotation; 10 µs = 4.6 mm of equatorial rotation.
Note 2: The IGS uses VLBI results from IERS Bulletin A to partially calibrate for LOD biases over 21-day sliding window, but residual time-correlated LOD errors remain.
Atmospheric Parameters
Final tropospheric zenith path delay 4 mm < 4 weeks weekly 2 hours CDDIS(US-MD)
IGN(FR)
KASI(KOREA) SOPAC(US-CA)
Ultra-Rapid tropospheric zenith path delay 6 mm 2-3 hours every 3 hours 1 hour CDDIS(US-MD)
KASI(KOREA)
Final ionospheric TEC grid 2-8 TECU ~11 days weekly 2 hours;
5 deg (lon) x 2.5 deg (lat)
CDDIS(US-MD)
IGN(FR) KASI(KOREA)
Rapid ionospheric TEC grid 2-9 TECU <24 hours daily 2 hours;
5 deg (lon) x 2.5 deg (lat)
CDDIS(US-MD)
IGN(FR)
KASI(KOREA)

See which products were most recently released on the product availability page, or view the traditional product summaries for the CB and the Global Data Centers: CDDIS, IGN and SIO.


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