Seven telescopes act as one
The huge Arecibo Observatory radio telescope in Puerto Rico, operated by Cornell University in cooperation with the National Science Foundation, recently was networked with six other telescopes in Chile, Germany, Italy, the Netherlands, South Africa and Sweden to create one of the largest virtual telescopes ever assembled.
The telescopes were linked via high-speed research and education networks serving North America and Europe using a combination of techniques to overcome the drawbacks of common networking protocols in sharing large volumes of data for immediate use. Using a technique called Very Long Baseline Interferometry (VLBI), the result was the equivalent of a single telescope nearly 11,000 kilometers in diameter making real-time observations of quasar 3C454.3.
The experiment was conducted by Express Production Real-time e-VLBI Service, a three-year project funded by the European Commission.
Internet2, the U.S. advanced research and education network, handled some of the transport of the real-time signals.
VLBI eliminates the shipping of disks of data from separate observations for correlation, allowing astronomers to respond to events as they happen. But the networking challenges are not trivial.
'Connecting telescopes across such large distances across many different domains poses some unique challenges,' said Arpad Szomoru, head of technical operations and research and development at the Joint Institute for VLBI in Europe. 'Transport via TCP/IP is not suitable, but the use of [User Datagram Protocol] can cause serious disturbances in connectivity for other users. For this demo, we have applied a number of methods, like the use of 1 gigabit/sec lightpaths with guaranteed bandwidth, [virtual local-area networks] and plain IP-routed connections. The success of this test demonstrates that global e-VLBI has become an operational reality.'
The telescope data was streamed to the Joint Institute for VLBI in Europe, where it was correlated and the results transmitted to Bruges, Belgium, as part of a live demonstration at the Trans-European Research and Education Networking Association Conference.
The only fly in the ointment on this side of the Atlantic is the acronym for the Joint Institute for VLBI in Europe. Apparently, the people who chose that name were not familiar with American slang.
William Jackson is a senior writer of GCN and the author of the CyberEye blog.