Correlation Center

Correlation on the Vienna Scientific Cluster

At TU Wien, we are correlating VLBI sessions on the Vienna Scientific Cluster (VSC) which is a collaboration of several Austrian universities that provides supercomputer resources and corresponding services to their users. For our purpose, we installed the Distributed FX (DiFX) software correlator and the Haystack Observatory Postprocessing System (HOPS) on the VSC-3 in June 2016 and on the VSC-4 in September 2019. The data transfer is realized with jive5ab enabling data transfer rates of (theoretically) up to 2 times 10 Gbits/s into the GEANT network. As part of these activities, we investigate the development of our own tools to close the gap between fringe fitting output and the VLBI module of the Vienna VLBI and Satellite Software (VieVS) which reads vgosDB files as input.

The VSC-3 consists of 2020 nodes comprising more than 32000 cores. It is equipped with a BeeGFS parallel filesystem developed for intensive i/o workloads, thus making it an appropriate computing environment for VLBI correlation. For example, we have been correlating and fringe-fitting the following session types on VSC-3: AUA sessions (including stations in Australia, South Africa, and New Zealand) and European Intensive sessions on the baseline Wettzell to Santa Maria. Recently, we started processing EU-VGOS sessions and we are part of a global correlator comparison of VGOS sessions.

The Vienna Scientific Cluster 4 is located at the Arsenal and has been switched on in 2019. We do have 10 private nodes there for correlation (480 cores) as well as private storage of 1 PByte. We plan to take on the correlation of several VGOS sessions in 2020.

Do not hesitate to ask Jakob Gruber to get more information about the current and possible correlation activities in Vienna. At TU Wien, we greatly appreciate the ongoing help by Jamie McCallum, University of Tasmania.