0 - Technical description of solution iaa2008a.crf

 1 - Technique:   VLBI

 2 - Analysis Centre:
       IAA
     
 3 - Software used:
       QUASAR
     
 4 - Data span:
     Jan 1980 - Mar 2009
     6353387 observations total.

 5 - Celestial Reference Frame: ICRF-Ext2 

     a - Nature:
     
         extragalactic

     b - Definition of the orientation:
         no-net-rotation using 203 defining radio sources of the ICRF (see Appendix B).

 6 - Terrestrial Reference Frame: vtrf2008 and associated 
                                  vtrf2008 velocity field 
                                  
        
      Definition of the origin:
     
         No net translation condition for 11 stations in the TRF
         (KOKEE   , WETTZELL, WESTFORD, ALGOPARK, NYALES20, ONSALA60,
          LA-VLBA , MATERA  , FORTLEZA, NOTO    , MK-VLBA)

	 i.e. sum over all translations of these stations is zero.

      Definition of the orientation:
     
         No net rotation condition for 11 stations in the TRF
         (KOKEE   , WETTZELL, WESTFORD, ALGOPARK, NYALES20, ONSALA60,
          LA-VLBA , MATERA  , FORTLEZA, NOTO    , MK-VLBA)
	 i.e. sum over all rotations of these stations is zero.

       Reference epoch:
     
         2000.0

     Constraints for time evolution:
     
         No net velocity adjustment condition in translation 
         and rotation for 11 stations in the TRF 
         (KOKEE   , WETTZELL, WESTFORD, ALGOPARK, NYALES20, ONSALA60,
          LA-VLBA , MATERA  , FORTLEZA, NOTO    , MK-VLBA)
        i.e. sum over all velocities adjustments in translation 
         and rotation of these stations TRF is zero.
         
     VLBI antenna axis offsets:      
     
       The values of VLBI antenna axis offsets were taken from official IVS list.


 7 - Earth orientation:

     a - A priori precession model:
     
	IAU 2000A Precession-Nutation Model
         
     b - A priori nutation model:
     
	IAU 2000A Precession-Nutation Model

     c - Short-period tidal variations in x, y, UT1:

    IERS convention 2003 model

 8 - Estimated Parameters:

    a. celestial frame: right ascension, declination (global)
 
    b. terrestrial frame:  X, Y, Z, Xdot, Ydot, Zdot (global)
 
    c. Earth orientation: Xp, Yp, UT1-TAI, Xc, Yc (local)
 
    d. zenith troposphere:   linear + stochastic signal (local).
 
    e. troposphere gradient: east and north (local)
 
    f. station clocks: quadratic (local) + stochastic signal (local).
 
 9 - Comments
 
   For coordinates of sources that observed lesser than 5 times the soft 10m constraint was applied.
   For velocities of station that operated less than in 5 session or time span less than 1 year
   the soft 10cm constraint was applied. (List of that sources and stations in Appendix A)