Considering that the VLBI technique uniquely connects the realms of Earth and Space, the meeting will be held under the theme “Linking the Celestial and Terrestrial Realms.” To recognize this linkage, the program features special sessions. Especially, Session 6 is dedicated to bridging the fields of astronomy, astrometry, and geodesy.
Session 1: Components
Conveners: Alexander Neidhardt, Fengchun Shu
The IVS is an international collaboration of organizations which operate or support VLBI components. These components acquire, correlate, and analyze VLBI data to produce geodetic, astrometric, and related results that are archived and publicized. The service achieves its objectives through coordinated contributions from Network Stations, Operation Centers, Correlators, Analysis Centers, Data Centers, and Technology Development Centers (TDCs). In this session we solicit status reports and activity updates from all IVS components. This may include descriptions of the progress done at new/future VLBI stations or advancements at existing sites, the buildout or upgrades of correlation facilities, developments at operation centers, projects at data and analysis centers, and current endeavors at TDCs, among others.
Session 2: VGOS Technique
Conveners: Chet Ruszczyk, Pepe López-Pérez
The VLBI Global Observing System (VGOS)—the next-generation VLBI system that uses smaller, faster antennas and a wide bandwidth (compared to the legacy S/X system)—has been in development for many years. The journey started with a vision paper in 2005 and went via a design-and-prototyping phase to the demonstration of the VGOS technique in 2018. While the system was declared operational in 2020 using a fledgling network, the journey of the development of the technique continues. In this session we seek contributions that address advancements of the VGOS technique. This includes but is not limited to the technical developments of the signal chain at the stations (e.g., feeds, backends, recording systems), improvements to the scheduling technique of the VGOS network (including optimizing the use of twin telescopes), optimization of the correlation process, observing frequencies, RFI mitigation or co-existing, data transport and storage considerations, and streamlining analysis capabilities, among other things.
Session 3: Operations
Conveners: Masafumi Ishigaki, Lucia McCallum
It is important to streamline and automate many aspects of VLBI operations in the IVS observing framework, as the current modus operandi covers only about 50% of the possible observing time, hindering the pursuit of continuous observing status. For this session, we solicit contributions that address automation of station operations, scheduling, and data transport. We also welcome ideas and implementations for enhanced monitoring, feedback, or performance indicators to improve the observing network efficiency (currently at 80%). Another focus of the session are the various IVS observing programs and networks, i.e., VGOS, legacy S/X, and K-band. We seek reports on the individual observing series and their experiences with new setups and modes.
Session 4: Products
Conveners: Karine Le Bail, Chris Dieck
One of the key objectives of the IVS is the generation of timely, high-quality products for the broader scientific and technical communities. The IVS provides the foundation for many scientific and practical applications that require an accurate quasi-inertial reference frame (e.g., high-precision positioning, navigation, and timing) as well as a variety of products with differing applications, timeliness, detail, and temporal resolution (e.g., all components of EOP, CRF, TRF, baseline lengths, tropospheric parameters). In this session we intend to address all operational aspects of IVS related to the generation of these products. We are interested in product improvement in terms of timeliness, robustness, accuracy, as well as other aspects. This requires an understanding of the status of the IVS products and their current/future limitations (including possible solutions to them). We seek contributions including but not limited to comparisons of predicted vs. actual performance; comparisons of S/X and VGOS performance; automatic data processing; improved scheduling; concrete suggestions for improved quality and/or timeliness of VLBI products.
Session 5: Forefront
Conveners: Helene Wolf, Rüdiger Haas
VLBI observations have greatly impacted astrometric and geodetic studies, contributing significantly to the establishment and maintenance of celestial and terrestrial reference frames (CRF, TRF) and the determination of Earth Orientation Parameters (EOP). The latter are essential for geophysical studies, such as tidal modeling and understanding the Earth's interior structure. In this session, we aim to highlight current efforts to expand the application of VLBI to frame ties (in space), deep space exploration, and other unique applications. We encourage contributions on determining terrestrial reference frame tie parameters and mitigating systematic errors. This includes, but is not limited to, the planned GENESIS and GRITSS missions.
Session 6: Crossroads VLBI
Conveners: Alet de Witt, Matthias Kadler
The VLBI technique uniquely connects the realms of Earth and Space—observing the same cosmic radio sources to understand both the distant Universe and the dynamics of the Earth. This session explores how VLBI serves as a bridge across astronomy, astrometry, and geodesy, highlighting the scientific and technical synergies between these disciplines. Contributions that explicitly connect the astronomical and geodetic communities—where geodetic data are used in astrophysical interpretation, or where astronomical insights inform the selection and characterization of geodetic reference sources—are particularly encouraged. Understanding the structure, variability, and physical properties of AGN remains fundamental for geodesists in maintaining and improving the celestial reference frame. We welcome contributions in the context of supermassive binary black holes, gravitational-wave counterparts, multi-messenger and high-energy astrophysics, pulsar astrometry, and maser-based Galactic mapping. Another goal of the session is to discuss perspectives on how future facilities such as SKA, ngVLA, and VGOS can further integrate astronomical and geodetic VLBI.
