iaa2005a.eopi.txt Contact: Zinovy Malkin (malkin@quasar.ipa.nw.ru) Last updated: Apr 07, 2006 Technical description of solution iaa2005.eopi 1. Purpose of solution: Intensives UT1 2 - Analysis Center: Institute of Applied Astronomy (IAA) 3. Short narrative description of solution: Sessions with the duration less than 16h and all sessions with two stations independently of the duration are analyzed for this solution. Files in the NGS format are used as source of observables. Model of reduction 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 VTRF2005 with the associated velocity field is used for station coordinates. Antenna thermal deformations are modelled using the IERS Conventions (2003) model with modification providing accounting for horizontal deformations and suitable for all mount types. Atmospheric loading model based on the time series computed by Leonid Petrov, GSFC is used. The main differences with the previous solutions are: - VTRF2005 is used for station positions, except Svetloe coordinates which are computed at the IAA - ICRF-Ext.2 is used - Relativistic model IERS Conventions (2003) is used 4. Estimated parameters: a. celestial frame: No b. terrestrial frame: No c. Earth orientation: UT1-UTC d. zenith troposphere: Random walk process e. troposphere gradient: No f. station clocks: Polynomial + random walk process g. baseline clocks: No h. other: No 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: VTRF2005 with update for SVETLOE b. a priori station velocities: VTRF2005 with update for SVETLOE c. reference epoch: 1997.0 d. station positions/velocities adjusted in solution: No 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: IERS Conventions (2003); zonal tidal variations are included in UT1; daily and subdaily variations are not included in EOP d. EOP estimation: UT1-UTC for every session 8. A priori geophysical models: a. troposphere: Saastamoinen model for HZD, VMF mapping function b. solid Earth tide: IERS Conventions (2003) c. ocean loading: IERS Conventions (2003) d. atmosphere loading: 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