In line with the IGS Multi-GNSS Experiment (MGEX) and with the increasing trend in the availability of Multi-GNSS products through different analysis centres, the IGS Analysis Centre Coordinator (IGS ACC) is trialling
an experimental MGEX orbit combination by adapting the existing combination software.
The intention is to compare how the next version of the combination software will perform against the existing software; therefore, the MGEX orbit combinations are not considered to be the final products at the moment.
These MGEX combinations also aim at comparing how different analysis centres perform considering the multi-GNSS products. They also encourage more contribution from the analysis centres to the MGEX products.
The experimental MGEX products are made available on a weekly basis, with a delay up to 13 to 20 days, similar to the final combination.
Since the purpose of the experimental phase is to include as many MGEX submissions as possible, the combination includes rapid MGEX submissions as well as final submissions combined together.
The AC SINEX transformations with respect to the current IGS reference frame are not applied in the current MGEX orbit combinations.
The orbit combination is performed separately for each constellation, using the same weighted average approach used in the current software for GPS orbit combination.
The results from different constellations are then compiled into one summary file and one sp3 file available at https://igsacc.s3.eu-central-1.amazonaws.com/products/mgex/final/.
Currently, only orbit combinations are available for the MGEX products.
The plots showing the Weighted RMS (WRMS) of the MGEX orbits, as well as those showing the estimated transformation parameters between individual ACs and the IGS combined orbits,
are useful for assessing the repeatabilities of the MGEX products by different analysis centres.
More information regarding MGEX products can be found at http://mgex.igs.org/.