Arecibo Observatory re-enters VLBI network with 21st-century backend

Arecibo Observatory (AO), with its recently upgraded Very Long Baseline Interferometer (VLBI) backend, successfully detected fringes in concert with antennae in the European VLBI Network (EVN). “The impact of AO on VLBI is nothing short of huge. Having AO back into a VLBI array enables unique VLBI science, including spectral line sensitivity and Fast Radio Burst (FRB) detection and localization, solely because of its huge collecting area. The detection and localization of FRBs is truly a novel technique for the VLBI,” explain Harro Verkouter, interim Head Technical Operations and R&D of the Joint Institute for VLBI ERIC (JIVE).

The upgraded system at AO consists of three key pieces of equipment, consisting of hard- and software, that need to work together to successfully participate in a VLBI observation: a FieldSystem, a dual Roach Digital Back End digital (RDBE) receiver and a 64 GB RAM Mark6 recorder. The system can process 512 MHz bandwidth both in PFB (Polyphase filter Bank) and DDC (Direct digital conversion) modes of operation, supports 4096 Mbps recording speed, and has 32 TB of disk capacity and also supports data e-shipping to the EVN software correlator at JIVE .

Mr. Verkouter visited Arecibo last year to modify, develop, and install new software to handle the AO integration and was glad to be on-site to assist with the reconfiguration of the equipment that simplifies the system. He was invited by Dr. Kristen Jones, former AO postdoctoral researcher under the Preeminent Postdoctoral Scholar program at UCF, in support of VLBI observations.

“The new system allows AO to follow new developments in VLBI technology once more, and increase their contribution to VLBI arrays by at least a factor of two,” Verkouter explained. “AO can now capture more data from astronomical sources. Especially in the global VLBI, where the EVN and VLBA jointly observe, the extremely sensitive baselines to the AO are fundamental for faint source detection and accurate phase calibration across the combined network.”

Congratulations to the team who worked on the upgrade project, which includes L. Quintero, A. Venkataraman from AO, H. Verkouter from JIVE, with significant support from U. Bach, B. Campbell, A. Szomoru from JIVE, H. B. Frej, M. Luce, J. Blanchard, W. Brisken from NRAO (National Radio Astronomy Observatory). The AO scientific staff who tested and commissioned the system include post-doctoral fellows S. Vaddi, (former) K. Jones, observations associate A. McGilvray, (former) VLBI scientist T. Ghosh and AO Emeritus astronomer C. J. Salter