ACADEMIA

Yesterday, collaborators in the EXPReS project (Express Production Real-time e-VLBI Service) conducted the first successful real-time correlation of e-VLBI data from Chinese and Australian telescopes, from Chinese and European telescopes, and from Australian and European telescopes. The observation was demonstrated before advanced networking experts at the 24th APAN (Asia-Pacific Advanced Network) Meeting in Xi'An, China. e-VLBI is a technique by which widely separated radio telescopes simultaneously observe the same region of sky, and data from each telescope are sampled and sent to a central processor via high-speed communication networks operating in real-time. This central data processor, a purpose-built supercomputer, decodes, aligns and correlates the data for every possible telescope combination and can generate images of cosmic radio sources with up to a hundred times better resolution than images from the best optical telescopes. e-VLBI data were previously obtained using European, Australian and Chinese telescopes in separate tests as part of EXPReS, a three-year project coordinated by the Joint Institute for VLBI in Europe (JIVE) and funded by the European Commission. Yesterday's tests, however, demonstrated the first real-time correlation results from Chinese-Australian and Chinese-European baselines. Data were also obtained from an Australian-European baseline for a short time as the target source set and rose in observing areas on opposite sides of the earth. The observations were conducted by JIVE staff members in collaboration with their European VLBI Network (EVN) partners in Europe, China and Australia. Participating radio telescopes included the Mopra and Sheshan telescopes during the Chinese-Australian part of the experiment, and the Sheshan, Darnhall, Jodrell Bank, Medicina, Torun and Westerbork telescopes in the European-Chinese part. Data were transferred to JIVE at a rate of 256 Mbps per telescope. Mopra was connected directly to JIVE through a dedicated 1-Gbps lightpath set up by the Australian, Canadian and Dutch national research and education networks (NRENs) AARNet, CANARIE and SURFnet, respectively. The Sheshan telescope was for the first time connected via the Chinese NRENs CSTNET and CERNET, the new high speed route across Siberia provided by the EC-sponsored ORIENT and TEIN2 networks, the pan-European GÉANT2 network and finally SURFNet. Most of the European telescopes have been connected for some time via dedicated lightpaths provided by the GÉANT2 partners. "This is a fantastic achievement," said Huib van Langevelde, director of JIVE, present at the APAN meeting in China. "When we started doing e-VLBI we wondered whether we would ever be able to connect to these far-away telescopes, because there are not only various oceans to cross but also many different network providers." Arpad Szomoru, head of R&D at JIVE, added, "We have recently developed and implemented various solutions that allow us to stream data over these enormous distances that overcome the problems with long round trip times over normal TCP/IP." Additional tests with telescopes in Puerto Rico and Chile are planned for the near future. EXPReS aims to implement up to 16 simultaneous 1 Gbps-network connections between the central processor at JIVE and partner telescopes across Europe, Asia, Australia, South Africa, South America and the USA by 2009.