Rapid
Introduction
- Rapid solutions use all available 24h sessions from 1984 to present, and the solution is updated twice per week.
- The combination is based on the addition of normal equation matrices, and makes use of datum-free normal equation matrices of VLBI sessions which are provided as SINEX files.
Two combined series are available:
- Combined series (dX, dY):
The nutation offsets are dX, dY referred to IAU2006 precession-nutation model excluding free core nutation Combined series (dPsi, dEps):
The nutation offsets are dPsi, dEps referred to IAU2000A precession-nutation model excluding free core nutation
- Combined series (dX, dY):
Combination Procedure
- Matrices are transformed into the mean epoch of all contributions by using the respective earth orientation parameter rates, before accumulating the individual normal equation matrices.
- Individual normal equation matrices are then transformed to a common set of apriori values for station coordinates and earth orientation parameters.
- Weighting factors determined by variance component estimation are applied to the normal equation systems.
- The datum-free normal equation matrices are accumulated.
- Earth orientation parameters are estimated by fixing all station components to their ITRF2008 values.
Comparisons for the purpose of quality control are carried out:
- internal comparisons of the individual solutions are made with respect to the combined solution,
- external comparisons are carried out with the earth orientation parameters of the IGS Final Combined Solution (igs00p03.erp) as well as with the IERS C04 (eopc04.62-now) earth orientation parameter series.