Earth Orientation parameters from the Matera Space Geodesy Center solution 
				
V. Luceri
e-GEOS, ASI/CGS, Matera, Italy

G. Bianco
Italian Space Agency (ASI), CGS, Matera, Italy

 
 The ASI EOP time series, submitted as operational series to IERS, provides 
 daily EOP and LOD from Lageos-I, Lageos II, Etalon I and Etalon II 
 data  collected from the worlwide network.
 The normal points are analysed in a 8-week arc, using the models listed 
 below in the technical description 
 Residual unmodelled effects in the orbit are minimized by the 
 estimation of empirical accelerations : 4-day constant and once-per-rev along 
 track acceleration and once-per-rev cross track acceleration for Lageos, 7-day 
 constant and once-per-rev along track for Etalon. 
 The normal equations are built up for all the parameters to be estimated, but 
 at this stage, they are solved only for the arc parameters, namely those 
 related to the orbit (state vector at the beginning of the arc and empirical 
 accelerations) and to the laser tracking systems (range biases for some 
 stations). 
 This arc inversion is performed with a bayesian least square procedure by the 
 NASA/GSFC GEODYNII software.
 All the normal equations with the updated arc parameters are then combined 
 solving for all the parameters in a least squares sense using the 
 NASA/GSFC SOLVE software: 3-D site coordinates, EOP (X,Y,UT1R-UTC) and LOD.
 The terrestrial reference frame is defined by fixing the coordinates and 
 velocities of 10 core sites to their ITRF values. 
 The estimated UT1-UTC are not delivered with this solution.
 The time series is weekly updated with the latest 8-week estimates. 
                                                                                
 
Contact person:

Vincenza Luceri
e-mail: cinzia.luceri@e-geos.it

 
 
		  Technical description of each arc solution 


 1 - Technique:                 SLR to Lageos-I, Lageos-II, Etalon I and Etalon II

 2 - Analysis Centre:           Centro di Geodesia Spaziale (G. Colombo), Matera, Italy

 3 - Software used:             GEODYN II and SOLVE

 4 - Data span                  latest 8 weeks

 5 - Celestial Reference Frame: 

     a - Nature:                        dynamical

 6 - Terrestrial Reference Frame: 

     a - Relativity scale:              LET

     b - Velocity of light:             299792458 m/s

     c - Geogravitational constant:     398600.4415 km3/s2

     d - Permanent tidal correction:    No

     e - Definition of the origin:      10 core stations fixed to ITRF2008 values

     f - Definition of the orientation: 10 core stations fixed to ITRF2008 values

     g - Reference epoch:               mean epoch of the arc

     h - Tectonic plate model:  	ITRF2008

     i - Constraint for time evolution:  SSV fixed to ITRF2008 values

 7 - Earth orientation: 

     a - A priori precession model:     IAU2000A

     b - A priori nutation model:       IAU2000A

     c - Short-period tidal variations in x, y, UT1:    modeled in UT1 but not in x, y

 8 - Estimated Parameters:

     a - Celestial Frame:     6 satellite elements every arc, 
					Lageos: constant and once-per-revolution along track 
					acceleration , once-per-rev cross track
					acceleration 
					Etalon: constant and once-per-revolution along track 
					acceleration 

     b - Terrestrial Frame:             site position

     c - Earth Orientation:             daily X, Y , UT1R and LOD 

     d - Others:                        range biases for a set of stations