NEWS

• Geodetic analysis of K band VLBI observations until 2024.0 (Hana Krásná et al.)
• Q band (43 GHz) celestial reference frame observed in 2021 (Hana Krásná et al.)
• Ambiguity Resolution in Legacy Sessions using Singleband Delays (Axel Nothnagel et al.)
• Optimal requirements for determining frame ties using VLBI observations to satellites (Wolf and Böhm)
• VieRDS for Simulating Source Structures at the Raw Data Level (Jakob Gruber et al.)
• Status Report and Aspirations: The Vienna Correlator in the VGOS Era (Jakob Gruber et al.)

The Vienna VLBI group also contributed to several other studies. For more information check out the program and the abstract book.

Jakob attended the “15th DiFX Users and Developers Meeting” in Socorro, New Mexico, USA, from September 11 to 15, 2023. This annual meeting is for the future planning, improvement, and documentation of the high-performance DiFX software. The Vienna Correlation Center uses DiFX in its operational and scientific work to process (correlate) raw VLBI data. The meeting was hosted by the National Radio Astronomy Observatory (NRAO). It was attended by more than 30 participants in person and many more online from 19 different international scientific institutes and agencies. Jakob gave a 30-minute talk on VGOS correlation at the Vienna Scientific Cluster and simulations of VLBI raw data. Some highlights of the many great talks were from H. Rottmann on energy efficient processing using SLURM at the Max-Plank-Institut für Radioastronomie in Bonn, from W. Brisken on the new developments of the DiFX simulation tool of VLBI raw data, from H. Ueshiba on automated correlation at the Tsukuba correlator, from J. Skeens on a combined interferometer approach of VLBI and GNSS data, and from A. Deller on the use of GPUs for VLBI correlation. In addition to the presentations, there were panel discussions on relevant topics such as the switch to GIT for version management of DiFX code.

We at Vienna Correlation Center are pleased to host the next DiFX Meeting 2024 in Vienna and look forward to many great presentations, interesting panel discussions, and a productive DiFX hackathon.

Picture: NRAO

• Earth orientation parameters estimated from recent Australian mixed-mode and Southern Intensive sessions (Sigrid Böhm et al.)
• The benefits of the Australian mixed-mode program (2018 -2023) for the celestial reference frame at S/X-band (Hana Krásná et al.)
• Neglected issues of terrestrial datum definition in VLBI (Lisa Kern et al.)
• Cross-polarization bandpasses of VGOS antennas (Frédéric Jaron et al.)
• Absolute orientation of Galileo orbits from simulated VLBI and GNSS observations (Helene Wolf et al.)

The book of abstracts can be found here.

In the week of 22 to 26 May 2023, the radio astronomical conference of the VLBI community took place in Bologna, Italy on the occasion of the 40th anniversary of the 32-m radio dish in Medicina. Hana Krásná was invited by the Scientific Organizing Committee to give a keynote talk about the relevance and unique contribution of VLBI to geodetic and astrometric products.

More information can be found here.

• Adjustment of orbital elements of Galileo satellite arcs with simulated VLBI observations (presentation, Helene Wolf¹ et al.)
• The importance of accurate a priori information for VLBI Intensive sessions (presentation, Lisa Kern¹ et al.)
• Earth orientation parameters determined from Very Long Baseline Array experiments conducted at K-band (24 GHz) (poster, Hana Krasna¹ et al.)
• Celestial reference frame determined from very long baseline interferometry experiments conducted at K-band (24 GHz) over the past 10 years (poster, Hana Krasna¹ et al.)
• The Vienna VLBI contribution to the ITRF2020 (poster, David Mayer² et al.)

More information on the REFAG2022, including abstracts and presentations, can be found here.