Scientific Program

Session 1
Station Reports and Technical Developments

The IVS has been promoting the VLBI Global Observing System (VGOS) over the past ten years. The ultimate goals of the VGOS are to achieve continuous observation (24 hours a day, 7 days a week), 1-mm position and 0.1-mm/year velocity accuracies, and a turnaround time to initial geodetic results of less than 24 hours. The VGOS systems have been improved and the network has been expanding by the commitments and investments of stations and developers to achieve the goals. In parallel with that, the legacy S/X network still plays a crucial role in determining the CRF and connecting the positions between the legacy and VGOS stations.

In this session, we seek contributions which demonstrate the efforts of improving the VLBI systems and network. We request contributions covering aspects of station activities, recent developments, simulations, and status and progress reports for VGOS and legacy systems. The technical developments may cover all signal chain components at the stations (like feeds, backends, recording systems) but also reference frequency generation and distribution, timing systems, e-transfer, and RFI excision techniques, among others.

Session 2
Observation Operation and Monitoring

Observing in telescope, correlator, and analysis networks provides the basis for all IVS work. The first aspect of this session focuses on the various IVS observing programs and their efficiency. Topics to be discussed can cover the observing network, the various existing and future observing modes and frequencies, cadences, or related. We explicitly solicit contributions from session advocates (session PIs), reporting on their observing series and experiences with new setups, e.g., with co-located geodetic instruments.

The second aspect of this session covers developments regarding operations and monitoring. With current network efficiency around 80% or less, ideas and implementations for improved monitoring, feedback, or performance indicators are welcome. Here we solicit contributions about workflows, staffing, remote control or automation of observations and correlation, as well as the organization and implementation of an efficient data transport. Ideas to solve current bottlenecks provide the basis for future decisions about observations and operations, in particular regarding the VGOS program.

Session 3
Correlation, Fringe Fitting and Source Structure

This session focuses on the current and future activities about data e-transfer, correlation, fringe fitting, and source structure. Presentations of the status/performance reports for correlation and fringe fitting of the various IVS observing series (VGOS, R1/R4, T2, CRF, Intensives, etc.) are solicited. Data e-transfer and near real-time correlation are critical for the VGOS to be fully operational with the expanding network; exploring various calibration methods and fringe fitting processes may allow for a more stable VGOS system. Also welcome are the submissions related to investigating source structure and core shift through imaging because the rigorous way of modeling these systematic effects is to treat imaging and image alignment as one calibration task in fringe fitting process.

Session 4
Scheduling, Operational Analysis and Products

The IVS data products serve as the public ‘face’ of the IVS, and a key objective of the IVS is the generation of timely, high-quality products for the broader scientific and technical community. This session brings together all operational aspects of IVS related to the generation of these products. The general question is, how can we improve the IVS products in terms of accuracy, robustness, timeliness, continuity, etc.? Some related questions are: What is the current status of the IVS data products? What are the current or future bottlenecks and problems, and are there solutions to these? What are the theoretical or practical limits on how well we can do?

We seek contributions in areas such as: Comparison of predicted vs. actual performance; Evidence that we are (or are not) making progress; Comparison of S/X and VGOS performance; Automatic data processing; Improved scheduling; Improving the quality of VLBI products; Concrete suggestions for how to improve the quality and/or timeliness of VLBI products.

Session 5
Interpretation and Comparison of VLBI Results in Geophysics, Geodesy and Astrometry

VLBI observations are influenced by a combination of several natural factors which must be considered in the data analysis. On the other hand, VLBI measurements can be used to retrieve information about the system Earth, positions of the VLBI telescopes, and observed active galactic nuclei. The analysis of VLBI observations produces values, time series, and long-term averages as well as rates of physical parameters. Analysis of dedicated sessions also produces images of celestial reference frame objects.

We seek contributions in topics such as the use of these VLBI products in modeling geophysical fluids from the atmosphere to the core, improvement of the precession-nutation model including models and predictions of free core nutation, investigation of the Earth rotation variations at different time scales, refinement of the terrestrial and celestial reference frames, detection and interpretation of the motions of specific sites and radio sources, atmospheric studies, astrophysical investigations, tests of relativity, and other scientific uses of geodetic and astrometric VLBI data and images. Other important topics are the comparison, validation, and combination of VLBI with other space-geodetic techniques, where special attention is expected to be given to the assessment of the actual accuracy and systematic errors of the VLBI-derived results. We are also particularly interested in presentations focusing on comparisons of VLBI observations obtained at higher radio frequencies and their validation against the legacy S/X radio bands. We further explicitly welcome contributions assessing the precision goals of VGOS and the performance of mixed-mode observations.

Session 6
Extending the Use of VLBI to Frame Ties, Deep Space Exploration and Other Areas

VLBI observations have greatly impacted astrometric and geodetic studies, contributing significantly to celestial and terrestrial reference frames (CRF, TRF) and Earth Orientation Parameters (EOP) determination. They are crucial in geophysical studies, like tide modeling and understanding deep Earth structure. In this session, we aim to highlight current efforts to extend the use of VLBI to frame ties, deep space exploration, and other unique applications.

VLBI has already proven invaluable in Lunar and Mars exploration for orbit determination and deep space probe positioning. VLBI observations of Gaia frame objects enable precise frame ties, enhancing EOP determination. The GENESIS-1 mission, approved by ESA at its 2022 Ministerial meeting, adds a new dimension, leveraging VLBI for satellite tracking to determine terrestrial reference frame tie parameters and mitigating systematic errors.

This session seeks contributions exploring multi-wavelength celestial reference frames, multi-technique terrestrial reference frames, deep space, and diverse demands of astrometric and geodetic VLBI in geophysical and astrophysical studies. We welcome insights into methodology, technical verification, and observation practices, and we invite you to delve into the expanding horizons of VLBI, where advancements like GENESIS-1 and Gaia contribute to shaping astrometric and geodetic research.