0 - Technical description of solution aus2019a.cat

 1 - Technique:   VLBI

 2 - Analysis Centre:
     Geoscience Australia

 3 - Software used:
     OCCAM 6.3

 4 - Data span:
     May, 1993 - March, 2019
     9,358,512 group delays 
     Weighted rms is 20.0 pks


 5 - Celestial Reference Frame: ICRF3

     a - Nature:

         extragalactic

     b - Definition of the orientation:  ICRF3

 6 - Terrestrial Reference Frame: itrf2008 and associated
                                  itrf2008 velocity field


     a - Relativity scale:

         Solar System Bary Center (SSB)

     b - Velocity of light:

         299792458 m/s

     c - Geogravitational constant:

         not applicable

     d - Permanent tidal correction:

         no

     e - Definition of the origin:

         NNT constraints on the daily basis for all
         VLBI stations, except Tigoconc, Yarra12M, Kath12M, Ishioka, Kunming, WETTZ13N,
         Metsahov, DSS65A, Parkes and Tsukub32, after the 2011 earthquake

     f - Definition of the orientation:

         NNR constraints on the daily basis for all
         VLBI stations, except Tigoconc, Yarra12M, Kath12M, Ishioka, Kunming, WETTZ13N,
         Metsahov, DSS65A, Parkes and Tsukub32 after the 2011 earthquake

     g - Reference epoch:

         2005.0

     h - Tectonic plate model:

         itrf2008 velocities used as apriori;
         exponential model for Gilcreek after the Denali, 2002
         earthquake [Titov, Tregoning; 2004]

     i - Constraints for time evolution:

         None


 7 - Earth orientation:

     a - A priori precession model:

         IERS 2003

     b - A priori nutation model:

         MHB2000

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

         Model used according to: R.Eanes (2000) as in IERS
         Conventions 2000


 8 - Estimated Parameters:

     a - Celestial Frame:

         - right ascension and declination of 4529 sources with three  
           and more observations (group delays) as global parameters;
           LOOSE (!) NNR constraint (1.d6) was imposed on 303 ICRF3 defining sources 
           during each session.
          
         - all sources are estimated as global parameters except to the
           39 ICRF2 unstable sources, 1038+52A and HR1099



     b - Terrestrial Frame:

         Daily  x, y, z values for all sites
         with further estimation of (x0,y0,z0) referred to
         2005.0 and corresponding velocities

     c - Earth Orientation:

         xp, yp, UT1-UTC, dpsi, deps

     d - Others:

         - clock offsets, rates and 2nd derivatives;
         - wet zenith tropospheric delays;
        

         Clock offsets, wet delays and EOP were
         considered as stochastic parameters with relevant
         covariance functions. VMF1 mapping function [Boehm,
         Schuh; 2004] has been applied for the troposphere
         modeling

         - wet troposphere gradients were estimated as daily parameters
           for comparison

         - Downweighting procedure: The observations below elevation 
           of 15 degrees were downweighted, but without addition of the extra
           noise in quadrature as it is done in CALC/SOLVE. 

         - Earlier observations betweem 1979 and May 1993 were not used because they are awful

         - Secular aberration drift is applied in accordance to the IVS WG8 recommendations [MacMillan et al., 2019]
 

    References:

Boehm J., H.Schuh, Vienna Mapping functions in VLBI analysis,
Geoph. Res. Lett., 31 L01603 DOI10.129/2003GL018984, 2004.
Eanes R., private communication, 2000.
Ma, C., et al., The International Celestial Reference
Frame as realized by Very Long Baseline Interferometry, AJ, 116,
516-546, 1998.
Titov O., P. Tregoning, Post-Seismic Motion of Gilcreek Geodetic
Sites Following the November, 2002 Denali Earthquake, in
International VLBI Service for Geodesy and Astrometry 2004
General Meeting Proceedings, edited by Nancy R. Vandenberg and
Karen D. Baver, NASA/CP-2004-212255, 2004.