The IVS VGOS Technical Committee (IVS VTC) discussed several times on how to maximize the benefits of VGOS for geodesy and astrometry. Unused potential for improvement was identified in (a) increasing the synthesized bandwidth per VGOS observing band from 480 MHz to 1024 MHz, and (b) distributing the four VGOS frequency bands between 3 and 14 GHz instead of only up to 10.6 GHz as is currently...
The Australian VGOS telescopes offer the capability of observing GNSS satellites in L-band, which is not common for traditional VLBI telescopes. Dual-band observations from several GPS satellites were recorded from the three telescopes and graciously shared by the University of Tasmania. Based on the correlation between the recorded samples and locally generated replicas, the signal traveling...
The GENESIS satellite, scheduled for launch in 2028, will contribute to the improvement of the International Terrestrial Reference Frame (ITRF), by combining the four major space geodetic techniques, namely GNSS, DORIS, SLR and VLBI, onboard a single platform at an altitude of 6000 km. The VLBI transmitter (VT) is one of the key instruments, designed to operate in two distinct transmission...
This report presents local-tie experiments using three co-located VLBI stations in China: Tianma and Sheshan in Shanghai, and Urumqi. The VGOS antennas were utilized in mixed-mode observations across the conventional S/X bands, followed by correlation of X-band-only data and subsequent post-correlation analysis. Phase delay analysis was performed to determine the relative coordinates of these...
VLBI tracking and analysis of Earth-orbiting satellites is becoming increasingly important in geodesy and fundamental astronomy, as demonstrated by recent initiatives such as GENESIS. A central requirement for these applications is the accurate modelling of near-field effects, along with realistic treatment of station clocks and atmospheric delays.
To support these scientific goals, we have...
The X-ray emission from resolved knots in the jets of many blazars cannot be explained as a simple extension of the radio synchrotron spectrum. So far no general consensus has been reached on the relative dominant contribution of the different broadband-emission mechanisms at play. In particular, observing the low radio frequencies provides valuable constraints to test different emission...
