Triple-twin flux density monitoring at VGOS frequencies

The VLBI Global Observing System (VGOS) has been operational since 2020. To optimize VGOS schedules and derive more accurate geodetic parameters, a SNR-based scheduling approach has recently been introduced. Still, many geodetic sources have poorly known radio flux densities in the operationally used VGOS frequency bands. We have carried out flux monitoring observations at Onsala Space Observatory (OSO) since 2023 in order to create a VGOS flux density catalog. However, not all VGOS sources are observable from Onsala. A complete and frequently updated catalog is only possible with the involvement of other stations. We here present early results of flux monitoring observations carried out with three pairs of twin telescopes simultaneously: Onsala, Ny-Ålesund and Wettzell. We compare the flux density values obtained by the different twin pairs, discovering discrepancies that need to be addressed before all twin pairs can be used for flux monitoring.