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• IAA VLBI Analysis Center
• IAA GNSS Analysis Center
• IAA SLR Analysis Center
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General Information

Earth Orientation Parameters (EOP) Service is operated by the Laboratory of Space Geodesy and Earth Rotation (LSGER) of the Institute of Applied Astronomy of the Russian Academy of Sciences (IAA). The main milestones of the IAA EOP Service history are:

March 1995		First IAA SLR EOP submission to IERS Annual Report
April 1995		Beginning of operational processing of SLR observations
May 1995		First appearance of IAA SLR EOP in the IERS Bulletin B
July 1995		First appearance of IAA SLR EOP in the IERS Bulletin A
February 1996		Beginning of operational processing of VLBI observations
March 1996		First IAA VLBI EOP submission to IERS Annual Report
		First appearance of IAA VLBI EOP in the IERS Bulletin B
August 1999		First appearance of IAA VLBI EOP in the IERS Bulletin A
October 2001		Beginning of operational processing of GPS observations
January 2002		First appearance of IAA GPS EOP in the IERS Bulletin B
March 2002		First IAA GPS EOP submission to IERS Annual Report
April 2004		Beginning of regular prediction of observed corrections to the IAU2000A model
August 2005		First issue of the weekly Bulletin

Now both operative and final EOP series have being computed. The IAA EOP series are routinely submitted to the IERS and IVS and are included in their operative and final combinations. Everyday operative processing of SLR, GPS and VLBI Intensive observations is fully automated.

CDDIS (NASA Goddard Space Flight Center, Greenbelt, MD, USA) is used as primary data center for VLBI, SLR and GPS observations, and EDC (Deutsches Geodätisches Forschungsinstitut, Munich, Germany) is used as supplement center for operational SLR data.

We use several program packages for analysis mostly developed at the IAA: GROSS for processing of the SLR observations and analysis of EOP and coordinates time series, OCCAM/GROSS for computation of EOP, station coordinates, and troposphere parameters time series from the VLBI observations, GRAPE for processing of GPS observations.

Special software has been developed for automatic data and results exchange inside IAA and between IAA and outer services and data centers and support of data bases related to the IAA EOP Service activity.

Software used for analysis includes both MS DOS/Windows (data analysis, internal data exchange, data storage) and Unix (data exchange with outer centers, web and ftp servers) components.

Products

Estimates of the full set of EOP (Earth pole coordinates Xp and Yp with rates Xp_rate and Yp_rate, Universal Time UT1-UTC or TAI-UT1, length of day LOD, celestial pole coordinates dPsi, dEps or dXc, dYc) are computed using observations collected from global VLBI, SLR and GPS networks. SLR series is updated daily, other series are updated 3-4 times per week. Accuracy of EOP is about 0.10-0.25 mas depending on technique.

• SLR series: daily estimates of Xp, Yp, LOD, TAI-UT1 with delay 2-3 days obtained from Lageos1&2 observations beginning from 1992 with one year prediction. TAI-UT1 series is aligned to IERS UT1 series for long-term variations. The series also includes interpolated FCN data described below. At the moment this series is recommended to the users interested in operational values of full set of EOP and prediction.
• 2nd SLR series: daily estimates of Xp, Yp, LOD, TAI-UT1, Xp_rate, Yp_rate with delay 1-2 days obtained from Lageos1&2 observations beginning from 1997 with one year prediction (PM rates are not presented in the file). TAI-UT1 series is aligned to IERS UT1 series for long-term variations. The series also includes interpolated FCN data described below.
• VLBI "24h" series: estimates of Xp, Yp, UT1-UTC, Xc, Yc at epochs of VLBI sessions with delay 1-2 weeks beginning from 1979.
• VLBI Intensives series: estimates of UT1-UTC at epochs of VLBI sessions with delay 2-8 days beginning from 1979.
• GPS series: daily estimates of Xp, Yp, Xp_rate, Yp_rate, LOD with delay 1-2 days beginning from 2000.
• Mean Pole coordinates beginning from 1965 with one year prediction. This data are recommended for computation of the Earth rotational deformations (pole tide) for high-accuracy station coordinates and satellite orbits.

Related links

• IERS:  International Earth Rotation and Reference Systems Service
• IVS:  International VLBI Service for Geodesy and Astrometry
• IGS:  International GNSS Service
• ILRS:  International Laser Ranging Service

Contact:   Dr. Iskander Gayazov, gayazov@ipa.nw.ru