iaa2007a.eops.txt Contact: Elena Skurikhina (sea@quasar.ipa.nw.ru) Last updated: 05.02.2007 Technical description of solution iaa2005a.eops 1. Purpose of solution: Session EOP 2 - Analysis Center: Institute of Applied Astronomy (IAA) 3. Short narrative description of solution: Sessions with the duration 16h and longer are analyzed for this solution. Files in the NGS format are used as source of observables. Model of reduction mainly follows IERS Conventions (2003). Wet tropospheric delays and clock offsets are modeled as random walk stochastic process and estimated using Kalman filter technique. Terrestrial reference frame ITRF2005 with the associated velocity field is used for station coordinates, ZELENCHUKSKAYA was added. New axis offsets were applied as recommended IVS. Antenna thermal deformations are computed using the IERS Conventions (2003) model with modification providing modelling the effect for all mount types, corrected. Bad meteo data replaced to ones from VMF1 files. The main differences with the previous solutions are: - ITRF05.cat is used for station positions and velocity; 4. Estimated parameters: a. celestial frame: No b. terrestrial frame: Session station coordinates (see note below) c. Earth orientation: Xp, Yp, UT1-UTC, Xc, Yc (see note below) d. zenith troposphere: Random walk process e. troposphere gradient: Yes f. station clocks: Polynomial + random walk process g. baseline clocks: No h. other: No Note: (Session station positions + dXc, dYc (optionally)) and (Xp, Yp, UT1-UTC, Xc, Yc) are estimated in separate runs. 5. Celestial reference frame: a. a priori source positions: ICRF-Ext.2 b. source positions adjusted in solution: No e. solution identification or reference: ICRF-Ext.2 6 - Terrestrial reference frame: a. a priori station positions: ITRF2005 b. a priori station velocities: ITRF2005 velocity field c. reference epoch: 2000.0 d. station positions/velocities adjusted in solution: No l. solution identification or reference: ITRF2005 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: IERS Conventions (2003); zonal tidal variations are included in UT1; daily and subdaily variations are not included in EOP d. EOP estimation: X, Y, UT1-UTC, dPsi, dEps for every session 8. A priori geophysical models: a. troposphere: Saastamoinen model for zenith delay, VMF mapping function b. solid Earth tide: IERS Conventions (2003) c. ocean loading: IERS Conventions (2003) d. atmosphere loading: numerical (convolution) model, GSFC time series 9. Data type: delays 10. Data editing: Only data with zero quality flag in NGS file are used; supplemental editing of outliers is applied during adjustment when necessary 11. Data weighting: Observations are weighted using std reported in NGS file and a priori additive variance depending on session and/or station. Elevation depending weighting is applied to the observations made below 10 deg. 12. Standard errors reported: Reported formal errors are derived from Kalman filter adjustment without supplemental correction 13 Software: OCCAM/GROSS 14. Other information: 1. Supplement fields after standard IERS/IVS ones contain: - experiment name - number of stations - chi-square - number of rejected observations - three columns containing internal information - list of stations used for computation of reported EOP, clock reference station is listed first