VLBI and Radio Astronomy

VLBI and Radio Astronomy Activities

Many Internet2 member institutions are developing and using high performance networking applications for radio astronomy, remote instrumentation, data sharing, and other collaborative activities. Click here for information on activities in optical astronomy.

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New!! Click here for BWCTL: Making e-VLBI Happen A Use Study for E2Epi

What is VLBI?

Very-Long-Baseline Interferometry (VLBI) is one of the most powerful techniques available for the high-resolution imaging of distant radio sources in the universe and for making accurate measurements of the motion of the earth in space. Multiple radiotelescopes scattered over the surface of the earth simultaneously record data from a radio source at streaming data rates as high as 1 Gbps for a 24-hour period; the data, which is then stored on magnetic tape and shipped to a central processing site for analysis. Using high-bandwidth networks, electronic transmission of VLBI data (known as “e-VLBI”) from this worldwide array of telescopes is now becoming a reality. The Internet2 VLBI Birds of a Feather (BOF) group focuses on the needs of the global VLBI community in the new era of high speed networks.

Activities

MIT Demos Live e-VLBI Transmission at SC Conference

Scientists from MIT Haystack Observatory, along with several collaborators, gave attendees at SC2004 (held 6-12 November 2004 in Pittsburgh) a first hand look at the application of high-speed networking to the practice of radio astronomy with the electronic transmission of Very Long Baseline Interferometry (e-VLBI) data. The live demo featured the real-time transmission of e-VLBI data from the Haystack's Westford Observatory in Massachusetts and NASA's Goddard Geophysical and Astronomical Observatory (GGAO) in Maryland, which were streamed over Internet2's Abilene Network to the Haystack correlator at 512 Mbps. The live results were displayed in a 3D plot (correlation amplitude, differential Doppler, differential delay) in Pittsburgh as the data were correlated.

During periods when the antennas were not available, the team transferred pre-recorded data from Westford, GGAO, the Onsala Space Observatory antenna in Sweden, and Kashima Space Research Center Observatory in Japan. The team at SC did an immediate correlation on this data, again showing results in Pittsburgh as the correlation proceeded.

Dr. Alan Whitney, Associate Director of the MIT Haystack Observatory, who headed the demo team at SC, would like to acknowledge the following collaborators:

Haystack Observatory: Roger Cappallo, Kevin Dudevoir, David Lapsley, Mike Poirier and Mike Titus.
NASA/GSFC GGAO Observatory: Jay Redmond
DRAGON collaborators provided much support both before and during the demo.
Kashima Observatory: Yasuhiro Koyama and colleagues
Onsala Observatory: Rudiger Haas and colleagues
NASA's Goddard Space Flight Center: Pat Gary and colleagues
MIT Lincoln Laboratory: provided Bossnet network and network support
National Science Foundation and NASA provided the funding to support the underlying work that made the demo possible and are helping to move e-VLBI towards routine operational reality. more...

Astronomers Demonstrate a Global Internet Telescope

On 22 September 2004, European and US collaborators demonstrated the use of advanced networks to link the radio telescopes electronically in real-time to perform radio astronomy experiments. The 20-hour long observations used the European VLBI Network (EVN) and involved radio telescopes in the UK, Sweden, the Netherlands, Poland, and Puerto Rico. The combined resolution of the antennas was at least 20 milliarcseconds, which is about 5 times better than the Hubble Space Telescope. Including the antenna at Arecibo, in Puerto Rico, also increased the sensitivity of the telescope array by a factor of 10. Each European telescope was connected to its country's advanced research network, and the data routed at 32 Mbps per telescope across GEANT, the pan-European research network and the Dutch network, SURFnet. Arecibo data were sent to Europe via AMPATH and Internet2's Abilene Network. The data were then delivered to the Joint Institute for VLBI in Europe (JIVE), the central processing facility for the EVN in the Netherlands. There, the 9 Terabits of data were fed in real-time into a correlator and combined to deliver the final data directly to the astronomers. Before the advent of advanced research and education networks, astronomers could not transfer the huge amounts of data required for real-time VLBI observations across the Internet, and instead used magnetic tapes which were shipped to central processing facilities. (Image courtesy of the European VLBI Network.) more...

MIT and Collaborators Achieve e-VLBI Transmission Milestone

Very-Long-Baseline Interferometry (VLBI) is one of the most powerful techniques for high-resolution imaging of distant radio sources in the universe and for making accurate measurements of the motion of the earth in space. Multiple radio telescopes located across the earth are used simultaneously in a powerful array to record data from a radio source, such as a distant quasar. Historically, VLBI data was gathered on tape or hard disk and then shipped to a central processing site for correlation analysis. Scientists at MIT's Haystack Observatory, along with several international collaborators, are using advanced networks to make electronic transmission of VLBI data (dubbed "e-VLBI") a reality. e-VLBI will transmit data over advanced networks directly from the antenna to the correlation site. On 25 March 2004, the first-ever successful real-time international transmission and processing of VLBI data was conducted between Haystack's Westford antenna in Massachusetts and the Onsala Space Observatory antenna in Sweden. Data from the Onsala observatory were transmitted over the GEANT network to New York and then over Internet2's Abilene Network to the Haystack Observatory. Although the data streamed at relatively low bandwidth (32 Mbps), it was still a milestone demonstration of real-time correlation of data from two antennas simultaneously. Using Internet2's open source End-to-End Performance Initiative Performance Environment System (E2E piPEs) BWCTL (Bandwidth Control) component and intermediate BWCTL beacons in Washington and London, researchers at Haystack could run tests between them to assist in diagnosing transcontinental network problems during the experiment. According to Dr. Alan Whitney, Associate Director of the MIT Haystack Observatory, "After demonstrating that international electronic transmission of VLBI data is possible, we're planning to scale our future experiments to use higher bandwidths, while still performing real-time analysis at greater speeds and on increasing quantities of data."

MIT Haystack Observatory

The Haystack Observatory at MIT is one of the pioneers in the field of Very-Long-Baseline Interferometry (VLBI) in radio astronomy. Very-Long-Baseline Interferometry (VLBI) is a high-resolution imaging technique used in radio astronomy. VLBI techniques involve using multiple radio telescopes simultaneously in an array to record data, which is then stored on magnetic tape and shipped to a central processing site for analysis. Using high-bandwidth networks, electronic transmission of VLBI data (known as “e-VLBI”) from this worldwide array of telescopes is now becoming a reality. Because the signal-to-noise ratio achieved by VLBI increases with the bandwidth of the observations, there has been a continual effort to increase the captured data rate. The advent of modern high-speed networks offers the possibility to transport VLBI data electronically with much higher data rates and lower costs to maximize the scientific potential of the observations. The electronic transmission of VLBI data (dubbed e-VLBI), though now in its infancy, is poised to become a reality as global network coverage and data-rates expand.

To do this, new protocols and strategies must be developed so these applications become efficient high-bandwidth ‘background’ users, while not significantly impacting other normal network traffic. Because many high-speed networks, such as Internet2, are not heavily loaded on an average basis, there is considerable potential for applications of this class to productively use background capacity, promoting better science for fewer dollars. MIT Haystack Observatory, in collaboration with the MIT Laboratory for Computer Science, was awarded a grant by NSF to develop new IP protocols specifically tailored to applications such as e-VLBI.

Alan Whitney, MIT Haystack Observatory, and Charles Yun, Internet2 Program Manager for Science and Engineering, will be among the presenters at the VLBI workshop, hosted by the Joint Institute for VLBI in Europe (JIVE) May 14-16, 2003 in Dwingeloo, the Netherlands. MIT Haystack hosted the first VLBI workshop held at Haystack Observatory in April 2002.

Aricebo Observatory

As one of the premier facilities for radio/radar astronomy and atmospheric science, the Aricebo Observatory in Puerto Rico is a key component of several large-scale research programs involving multiple instruments around the globe and in space. The 305m telescope's unique sensitivity is needed for quick confirmation of new discoveries within its space and frequency coverage, precise tracking and imaging of small solar system objects which may be visible for only a few days, and measurement of ionospheric effects barely detectable elsewhere. The design of the instrument is shaped by multidisciplinary needs and enables it to respond quickly and flexibly to "targets of opportunity". A remote observing capability is useful for flexible telescope scheduling, as well as for coordinated observing projects with multiple spaced instruments, which are common in atmospheric investigations. Plans call for development of a "Virtual Control Room" permitting remote observers to perform high-quality observations over Internet2 without travelling to the site.

Given the large data-gathering capability of the Arecibo telescope, special techniques are often required to perform realtime signal processing and parameter estimation on the acquired data. Certain investigations e.g pulsar searches require supercomputer-class computing resources to implement sophisticated reduction algorithms. Good use of the available observing time often implies getting data reduced before the next available slot, i.e high-bandwidth access to a supercomputer. Here the role of the Observatory is that of a source of raw data with a participating supercomputer center supplying the computational resources.

Presentations from the Astronomy BOF meeting, held at the AMPATH Workshop, January 29-31, 2003.

e-VLBI: A High-Data-Rate Radio-Astronomy Application for Internet2 [PPT] [html], Spring 2003 Internet2 Member Meeting, April 10, 8:45-10:00 a.m. Presenter, Alan Whitney.

Connecting the Global VLBI Array in the New Era of High Speed Networks, first eVLBI Workshop, MIT Haystack Observatory, 8-9 April 2002. [Meeting Summary]