spu2015a.eops.txt

 Technical description of solution  spu2015a

 1.  Purpose of solution:  Session EOP

 2.  Analysis Center:  Saint-Petersburg University (SPU)

 3.  Short narrative description of solution:

 Observational VLBI groupe delays (IRIS-A and NEOS-A since
 2-Jan-1989 and R1, R4 since 1-Jan-2002) have been analyzed for this solution. 
 Reductional model is realised in accordance with the IERS Conventions 2003.
 Relativistic corrections are calculated in accordance with the IERS consensus 
 model.
 Celestial reference frame was fixed to the ICRF Extension catalogue.
 A priori terrestrial reference frame was the VTRF2005 catalogue, but daily station 
 coordinates have been estimated  under NNR and NNT constraints. VTRF2005 velocity field is used for station coordinates calculation.  
 All parameters under estimation have been adjusted
 using Kalman filter technique. 
 Troposphere wet delay is modeled as a stochastic process like
 random walk with spectral density equal to 0.1
 picosec**2/sec. Clock offset is considered as a random walk stochastic 
 process with spectral density equal to 1.0 picosec**2/sec. 
 Clock rate is considered as a constant parameter. Troposphere gradients 
 are modeled as a constant parameters.

 4.  Estimated parameters:

     a. celestial frame:  No

     b. terrestrial frame:  Yes

     c. Earth orientation:  X, Y, UT1-UTC, dpsi, deps

     d. zenith troposphere:  Random walk process

     e. troposphere gradient:  constant parameters

     f. station clocks:  Offset as a random walk process, rate as a constant

     g. baseline clocks:  No

     h. other:  No

 5.  Celestial reference frame:

     a. priori source positions:  ICRF Ext.2

     b. source positions adjusted in solution:  No

     c. solution identification or reference:  ICRF Ext.2

 6 - Terrestrial reference frame:

     a. priori station positions:  VTRF2005

     b. priori station velocities:  VTRF2005 velocity field

     c. reference epoch:  1997.0

     d. station positions/velocities adjusted in solution:  station positions 
        adjusted on daily basis
        
     l. solution identification or reference:  VTRF2005

 7.  Earth orientation:

     a. a priori precession model:  IAU2000A

     b. a priori nutation model:   IAU2000A

     c. a priori short-period tidal variations in x, y, UT1:
        Model (IERS Conventions 2003)

     d. EOP estimation:  X, Y, UT1-UTC, dpsi, deps every session

 8.  A priori geophysical models:

     a. troposphere: VMF1 mapping function for dry and wet delays

     b. solid Earth tide:  IERS Conventions 2003.

     c. ocean loading:  IERS Conventions 2003.

     d. atmosphere loading: information about local pressure
        for separate VLBI sites has been used from server of
        Onsala Space Observatory

 9.  Data type:  delays

 10. Data editing:  Only data with zero quality flag in NGS format are used

 11. Data weighting:
     Observations with elevation less than 5 degrees to be divided by
     sin(elevation).  Observations with elevation more than 5
     degrees are not weighted as a rule, but Kalman filter
     approach checks a quality of every observation and
     downweights it in case of bad result.

 12. Standard errors reported:  Formal errors are derived from
     Kalman filter adjustment

 13  Software:  OCCAM v. 6.2

 14. Other information:

 ------------------------------------------------------------------------------
 Dmitriy Trofimov   senior lecturer of Astronomy department
 Tel:    +7-(812)-428-41-99
 Fax:    +7-(812)-428-71-29

 Sobolev Astronomical Institute of Saint-Peterburg University
 Universitetskii pr., 28, Petrodvorets, Saint-Petersburg, Russia, 198504
 d.trofimov@spbu.ru