IGS Products

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)
Broadcast	Sat. clocks	~5 ns RMS ~2.5 ns SDev	real time	--	daily	CDDIS(US-MD) SOPAC(US-CA) IGN(FR)
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)
Ultra-Rapid (predicted half)	Sat. clocks	~3 ns RMS ~1.5 ns SDev	real time	at 03, 09, 15, 21 UTC	15 min
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)
Ultra-Rapid (observed half)	Sat. clocks	~150 ps RMS ~50 ps SDev	3 - 9 hours	at 03, 09, 15, 21 UTC	15 min
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)
Rapid	Sat. & Stn. clocks	~75 ps RMS ~25 ps SDev	17 - 41 hours	at 17 UTC daily	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)
Final	Sat. & Stn. clocks	~75 ps RMS ~20 ps SDev	12 - 18 days	every Thursday	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		~5 cm	12 - 18 days	every Thursday	15 min	CDDIS(US-MD)
Final		~5 cm	12 - 18 days	every Thursday	15 min	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)
Final positions	vertical	6 mm	11 - 17 days	every Wednesday	weekly	CDDIS(US-MD) SOPAC(US-CA) IGN(FR)
Final velocities	horizontal	2 mm/yr	11 - 17 days	every Wednesday	weekly	CDDIS(US-MD) SOPAC(US-CA) IGN(FR)
Final velocities	vertical	3 mm/yr	11 - 17 days	every Wednesday	weekly	CDDIS(US-MD) SOPAC(US-CA) IGN(FR)
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.