Please note that this session was withdrawn and is no longer available in the respective programme. This withdrawal might have been the result of a merge with another session.
G2.4 | Global Geodetic Observing System: VLBI component merit
EDI
Global Geodetic Observing System: VLBI component merit
Convener: Anastasiia WalentaECSECS | Co-conveners: Minghui Xu, Aletha de Witt, Lucia McCallum
Very Long Baseline Interferometry (VLBI) assumes a fundamental role within geodesy and astrometry. VLBI stands apart as the sole method with the capability to both establish and sustain the International Celestial Reference Frame (ICRF). Moreover, VLBI’s proficient is in delivering the complete set of Earth orientation parameters (EOP), including the direct measurement of nutation parameters and the Earth rotation angle (UT1 – UTC). VLBI's significance extends to its substantial contributions to the International Terrestrial Reference Frame (ITRF), notably in terms of scale determination, underpinned by a comprehensive observational record of nearly four decades. VLBI also stands as a key contributor to the Global Geodetic Observing System (GGOS), primarily through the development and role-out of the VLBI Global Observing System (VGOS) by the International VLBI Service for Geodesy and Astronomy (IVS).
The established configuration of the legacy S/X-band observations is focused on facilitating ionospheric corrections. Contrasting this, VGOS observations operate within a broad frequency spectrum, thereby enabling a comprehensive ionospheric correction capabilities. The ICRF3 was constructed using VLBI data at the standard S/X frequencies, along with observations at K-band and X/Ka-band, making it the first multi-frequency frame. The promise of constructing a VGOS CRF in parallel with the continued utilization of the S/X CRF not only anticipates enhancing our capabilities but also promises to fortify the VGOS network, ensuring its resilience and reliability.
The backward compatibility with the running legacy VLBI network is to be considered as a tool to bridge nearly 40 years of legacy and last 4 years of VGOS observations. VGOS antennas were designed with two aims: to increase the measurement precision, from a cm-level to the GGOS goal of 1 mm; to increase the observational cadence, from 2-3 sessions per week to continuous observations. In this session we explicitly seek contributions to revisit the original goals and map the future VLBI contribution to GGOS. This session will place the emphasis on VGOS' potential to address signal propagation effects caused by temporal and spatial variations of atmospheric water vapour through its agile and compact antenna design. Besides this, we welcome the contributions dedicated to the satellite tracking with the fast VGOS antennas, an approach that promises to enhance and homogenize the reference frame determination.