NEWS

15th DiFX Users and Developers Meeting 2023

15th DiFX Users and Developers Meeting 2023

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

Vienna VLBI Group at EVGA 2023

Vienna VLBI Group at EVGA 2023

In the week of 11 to 15 June 2023 the 26th European VLBI Group for Geodesy and Astrometry (EVGA) Working Meeting took place in Bad Kötzting, Germany, near the collocation station Wettzell. The Vienna VLBI Group participated with the following presentations:
  • 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.

IVS Technical Operations Workshop 2023

IVS Technical Operations Workshop 2023

The 12th IVS Technical Operations Workshop (TOW) took place from April 30 through May 4 2023 at MIT Haystack Observatory in Westford, Massachussetts, USA. It was directly followed by a Correlator Workshop on May 4-5. Frédéric Jaron gave a lecture on the application of PolConvert to geodetic VLBI (VGOS) data at the TOW (see the picture), and a talk about results from a research and development VGOS session at the correlator workshop.

More information can be found here.

Bologna VLBI: Life begins at 40!

Bologna VLBI: Life begins at 40!

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.

Vienna VLBI Group at REFAG 2022

Vienna VLBI Group at REFAG 2022

In the week of 17 to 20 October 2022, the IAG International Symposium on Reference Frames for Applications in Geosciences (REFAG) took place in Thessaloniki, Greece. There have been four contributions from the Vienna VLBI group1 and one from the Federal Office of Metrology and Surveying (BEV)2:
  • 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.

Paper on the evaluation of satellite observations with VLBI published

Paper on the evaluation of satellite observations with VLBI published

The installation of a VLBI transmitter on Galileo satellites would allow observing satellites besides quasars with VLBI telescopes.
Three additional Dilution of Precision (DOP) factors were introduced which are representing the sensitivity of a satellite observation towards the components of the satellite position in the local orbital.
These factors were used for evaluating observations to Galileo satellites with VLBI in the paper published in the International Association of Geodesy Symposia (2022).
Dr.-vlbi Jakob Gruber

Dr.-vlbi Jakob Gruber

On June 30, 2022, Jakob Gruber successfully defended his PhD thesis on Raw Data Simulation and Correlation of VLBI data. After the presentation of his thesis, Jakob withstood the difficult questions from Axel Nothnagel, Jamie McCallum and Johannes Böhm. Congratulations and thanks for the nice party in Hof3! @tu_wien @geodepartment @j_boehm72

 

Excursion to the Geodetic Observatory Wettzell

Excursion to the Geodetic Observatory Wettzell

On June 20, the excursion to the Geodetic Observatory Wettzell organised by the Vienna VLBI Group took place. This year, 34 students and 7 staff members participated in the trip to the Bavarian Forest. At the observatory, we were able to inspect three VLBI antennas, two SLR/LLR systems, many GNSS antennas and a DORIS beacon. Moreover, we were able to get insight information on the on-site ring laser and additional telescopes observing the space weather.
A big thanks to our colleagues at Wettzell for this fascinating tour!