The ITRF94 solution is available on this server for wide distribution. The determination of this solution was
a lenghty process for several reasons :
- The analysis strategy and the choice of the published results were redefined with regards to previous
years. The new strategy was to perform a global combination of a selection of submitted solutions and then
to compare the other solution to this combination. The basic criteria for this combination were :
- To obtain combined positions and velocities without use of a priori geophysical model
(plate tectonic or postglacial rebound)
- To select the solutions (called class I) which provided full covariance matrices with adjusted
velocities as well as good quality
- To select a datum without ERP constraints, with best orientation continuity with past BIH/IERS one,
and with best estimate of origin and scale extracted from those solutions where this information was
physically estimable (The selection was circulated in the IERS Working Group on ITRF Datum).
- The necessity to use a standard format (SINEX/ISEF1) to get individual solutions with full covariance
matrix
- Various small misunderstandings between ACs and ITFS concerning exchanged data had to be clarified
- Delicate estimate of a scaling factor for each received covariance matrix in order to get a realistic
combination
- Analysis of datum parameters and final selection
The computations were reiterated up to the point that we estimated that the solution fulfilled reasonably the
previously described criteria. Finally a detailed analysis of results for each station has led to a classification
of the ITRF94 coordinates for the points of the IERS Network.