************************************************************************ IERS Message No. 491 November 06, 2023 ************************************************************************ EGU24: Global Geodetic Observing System: VLBI component merit Dear Colleagues, We are glad to announce that the recently proposed session at EGU24 was accepted. EGU24 takes place as usual in Vienna, Austria on the week of 14-19 April 2024. I strongly encourage everyone to consider the abstract submission to this session dedicated to the VLBI merit as a part of GGOS. The abstract submission deadline is 13:00 CET, 10 January 2024 and 13:00 CET, 1 December 2023, if you apply for financial support. G2.4: Global Geodetic Observing System: VLBI component merit 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. Share: https://meetingorganizer.copernicus.org/EGU24/session/49270 For your information deadlines and hints: * Submit your regular abstract to the session of your choice by 13:00 CET, 10 January 2024. * Apply for financial support by submitting your abstract by 13:00 CET, 1 December 2023. * Submit an abstract in an EOS session in addition to a regular abstract, this is the only exception to the one abstract rule (unless you are a solicited speaker ). * If you have been invited as a solicited speaker , ensure you have the TAN number from your convener that you need to submit your solicited talk in addition to a regular abstract. * Looking for tips on how to submit your abstract? Find instructions on how to submit on the EGU24 website . * Prepare your calendar with all the EGU24 important dates by checking the Deadlines and Milestones page. For full and detailed info: https://www.egu24.eu/programme/how_to_submit.html Thank you in advance for your collaboration. Regards, Anastasiia Walenta On behalf of Convener Team: Anastasiia Walenta, Minghui Xu, Aletha de Witt, Lucia McCallum ************************************************************************ IERS Messages are edited and distributed by the IERS Central Bureau. If not stated otherwise, the IERS is only the distributor of the message and is not responsible for its content. To submit texts for distribution, please write to . To subscribe or unsubscribe, please create an IERS account or modify it: https://www.iers.org/Login/Login/EN/login_node.html or write to . Archives: https://www.iers.org/IERS/Messages ************************************************************************