BKG/DGFI-TUM IVS Combination Centre's advancements within the framework of the IVS Contribution to ITRF2020-u2025

The BKG/DGFI-TUM IVS Combination Centre (IVS-CC) officially contributes to the realization of the International Terrestrial Reference Frame (ITRF) by incorporating the contributions from the IVS Analysis Centres (ACs).

For the 2025 update of the ITRF 2020 (ITRF2020-u2025), the IVS initiated a reprocessing of the full VLBI observation history since 1979. Besides S/X-band and VGOS sessions, for the first time, K-band VLBI sessions are included in the ITRF contribution. Moreover, on an empirical basis, the IVS-CC provides combined normal equations that include radio source positions as parameters, allowing for the joint and consistent computation of terrestrial and celestial reference frames, and EOPs as the link between them.

This presentation focuses on developments in the framework of the IVS-CC combination setup for the IVS contribution to ITRF2020-u2025.  A total of 7613 S/X, 219 VGOS, and 229 K-band VLBI sessions will be used for this study. We begin with a description of our combination setup, followed by validation of the input data provided by the contributing ACs and the combined IVS contribution to ITRF2020-u2025. The investigation focuses on the quality of geodetic products estimated by different session types across eclectic frequency bands, including legacy S/X, VGOS, and K-Band.