Technical description of solution USNO9903 Intensives 1. Purpose of solution: Intensive EOP 2. Analysis center: USNO 3. Short narrative description of solution: All of the short duration ``Intensive'' sessions used to determine the UT1 on a daily basis are reduced by the USNO VLBI program using the the Navy 1999-3 (n9903) reference system. Only tropospheric zenith and clock parameters, and the UT1 itself, are estimated in this solution. 4. Estimated parameters: a. Celestial frame: Fixed to the n9903 values. b. Terrestrial frame: Fixed to the n9903 values. c. Earth orientation: UT1-TAI only d. Zenith troposphere: Offset and rate for each session. e. Troposphere gradient: Not adjusted. f. Station clocks: Continuous piecewise linear with 180 min interval. Rate constraint is 10 E-14. g. Baseline clocks: Not generally used as most are single baseline. h. Other: Global antenna axis offsets are fixed at the n9903 values. 5. Celestial reference frame: a. A priori source positions: Navy 1999-3 b. Source positions adjusted in solution: no e. solution identification or reference: Navy 1999-3 used without adjustment. A few sources have unstable positions but are used in early Intensives. To account for the variations in the positions of these sources, their observational formal errors were increased. The following table shows the sources with large positional instabilities and the ``additive noises'' used to inflate the formal errors for these sources : Source delay rate <--add noise--> psec fs / s 3C273B 100.0 300.0 3C345 100.0 300.0 3C454.3 100.0 300.0 3C84 100.0 300.0 3C48 100.0 300.0 6 - Terrestrial reference frame: a. A priori station positions: Navy 1999-3 b. A priori station velocities: Navy 1999-3 c. Reference epoch: 1997.0 d. Station positions/velocities adjusted in solution: no l. solution identification or reference: Navy 1999-3 7. Earth orientation: a. A priori precession model: IERS Bulletin A b. A priori nutation model: IERS Bulletin A c. A priori short-period tidal variations in x, y, UT1: GSFC hf996b UT1 tidal terms (microseconds) l l' F D Om GST | Cos | Sin | +pi | | | ----------------------------------------- 0 0 0 0 0 -1 8.390541 15.603754 0 0 2 -2 2 -1 -2.270974 -4.520974 0 0 2 0 2 -1 -13.496891 -17.709334 1 0 2 0 2 -1 -2.863498 -4.787981 0 1 0 0 0 -1 -.891044 1.863314 1 0 0 0 0 -1 1.485515 .709235 0 0 0 0 0 -2 .247526 1.665623 0 0 2 -2 2 -2 -.981241 8.048208 0 0 2 0 2 -2 -10.109943 14.766708 1 0 2 0 2 -2 -2.418065 3.362383 2 0 2 0 2 -2 -.423254 .898874 0 0 2 2 2 -2 -1.017729 .588472 -1 0 2 2 2 -2 .105177 .494085 0 0 2 0 1 -2 -.351840 -1.137950 -1 0 2 0 2 -2 .383683 -.160874 0 1 2 -2 2 -2 -.472836 .097590 0 0 0 0 1 -2 2.173278 .735157 0 0 2 2 2 -1 -.289042 -.403689 1 0 2 0 1 -1 -.539830 -.902636 -1 0 2 2 2 -1 -1.082247 -1.486773 0 0 2 0 1 -1 -2.545049 -3.339370 -1 0 2 0 2 -1 .800661 .621148 0 1 2 -2 2 -1 .171219 -.180862 0 0 0 0 1 -1 1.137897 2.116129 -1 0 0 0 0 -1 -.714221 1.017338 0 0 -2 0 -2 -1 1.498264 -.334916 0 0 -2 0 -1 -1 1.120941 .793015 ----------------------------------------- Polar motion tidal terms (microarcseconds) l l' F D Om GST | Cos | Sin | +pi | | | ----------------------------------------- 0 0 0 0 0 1 144.320341 -78.879960 0 0 -2 2 -2 1 -47.081071 21.289918 0 0 -2 0 -2 1 -142.621076 50.739409 -1 0 -2 0 -2 1 -32.603034 12.082873 0 0 0 0 0 -2 -26.667130 2.956205 0 0 2 -2 2 -2 -69.723790 103.830117 0 0 2 0 2 -2 -4.469703 261.522044 1 0 2 0 2 -2 -3.537164 39.891304 0 0 0 0 0 2 1.935495 -30.107929 0 0 -2 2 -2 2 -.486089 -15.524156 0 0 -2 0 -2 2 12.664993 -66.365149 -1 0 -2 0 -2 2 .137290 -13.615587 -2 0 -2 0 -2 2 -.671647 5.131798 0 0 -2 -2 -2 2 -4.298936 -2.595443 1 0 -2 -2 -2 2 5.282140 -.843876 0 0 -2 0 -1 2 -13.053854 11.657971 1 0 -2 0 -2 2 8.292567 3.728337 0 -1 -2 2 -2 2 -.417373 -3.437100 0 0 0 0 -1 2 25.902757 .373514 0 0 -2 -2 -2 1 -.896038 -.249728 -1 0 -2 0 -1 1 -6.147779 2.277775 1 0 -2 -2 -2 1 -5.697683 3.578188 0 0 -2 0 -1 1 -26.893352 9.567638 1 0 -2 0 -2 1 -11.768551 4.050336 0 -1 -2 2 -2 1 -1.052071 -3.590543 0 0 0 0 -1 1 19.572080 -10.697407 1 0 0 0 0 1 .828564 -5.020211 0 0 2 0 2 1 11.042002 -11.297487 0 0 2 0 1 1 3.918362 -1.787878 2 0 2 0 2 -2 1.194979 10.942462 0 0 2 2 2 -2 -3.686578 5.621777 -1 0 2 2 2 -2 -8.400973 14.598007 0 0 2 0 1 -2 -3.252330 .560673 -1 0 2 0 2 -2 3.524189 -10.972068 0 1 2 -2 2 -2 -8.310187 -5.687969 0 0 0 0 1 -2 -1.871795 16.865984 2 0 2 0 2 -1 -.13 -1.24 ----------------------------------------- d. EOP estimation: UT1-TAI for each session. 8. A priori geophysical models: a. Troposphere: NMF ``dry'' mapping function with surface pressure. NMF ``wet'' mapping function for zenith troposphere partials. b. Solid Earth tide: IERS Conventions c. Ocean loading: IERS Conventions d. Atmosphere loading: NONE 9. Data type: Group delays and phase delay rates 10. Data editing: 7 deg elevation cutoff 11. Data weighting: Additive variance for data from each site for each session from database, together with the additional source additive variance as described in 5 e. 12. Standard Errors Reported : All of the standard errors are derived from Solve formal errors, based on the propagation of the delay and rate errors (including an additive variance to make the residual CHI square consistent with the number of degrees of freedom, as discussed in # 11) into the parameter covariance matrix. 13. Software: CALC 8.2, SOLVE 5.0115, dated 97.07.23 14. Other information: See ftp://casa.usno.navy.mil/navnet/README.n9903 for further information. Solution statistics : a. Data span: 19990102 - 19990617. b. Number of observations / sessions : 2430 delay and rate observation pairs from 125 observing sessions. c. Number of sources used : 51 sources d. Number of stations used : 5 stations. e. Residual Statistics : Weighted Root Sum Square (wrms) delay residual scatter of 23.92 picoseconds, and a wrms phase delay rate scatter of 100.69 femto seconds / second.