Intensive solution maintained at OPAR opa2010i
1. Purpose of solution: UT1 series.
2. Analysis center: OPA (Paris Observatory).
3. Short narrative description of solution: The solution processes intensives
sessions after 2006.01.01 in order to produce UT1 consistent with VTRF 2008a,
ICRF2 and C04 Earth orientation data.
4. Estimated parameters:
a. UT1.
b. zenith troposphere: offset.
c. station clocks: quadratic drift.
5. Celestial reference frame:
a. a priori source positions: ICRF2.
b. source positions adjusted in solution: no.
6. Terrestrial reference frame:
a. a priori station positions: VTRF 2008a.
b. a priori station velocities: VTRF 2008a.
c. station positions/velocities adjusted in solution: no.
7. Earth orientation:
a. a priori precession model: IAU 2000.
b. a priori nutation model: IAU 2000 + correction fitted to C04. The correction
includes a variable FCN model, a slope, and a number of tidal periodic terms.
c. a priori short-period tidal variations in x, y, UT1: IERS 2003.
8. A priori geophysical models:
a. troposphere: VMF1.
b. solid Earth tide: IERS Conventions 1996, p.56-65, step 1 and step 2,
anelasticity variant, including tides of the 3-rd order.
c. pressure loading: ocean loading displacements computed from FES 2004.
Atmospheric loading displacements obtained from the APLO service
(Petrov & Boy 2004).
9. Data type: group delays.
10. Data editing: 5 degree elevation cutoff.
11. Data weighting: weights are defined as follows: 1/sqrt ( f**2 + a**2 )
where "f" is the formal uncertainty of the ionosphere free linear combination
of group delays at X- and S-band obtained by fringe fitting on the base of
achieved signal to noise ratio. Station-dependent parameter "a" was computed
for each session by an iterative procedure such that the ratio of the sum of
squares of the weighted residuals to the estimate of their mathematical
expectation is about unity.
12. Standard errors reported: all errors are derived from least-squares
estimation propagated from the data weights and the constraints applied
to the troposphere, clock and EOP parameters.
13. Software: CALC 10.0, SOLVE revision date 2010.05.21.
14. Other information: solution is reported at http://ivsopar.obspm.fr.