Research Networks and Astronomy

1. Research Networks and Astronomy Richard Schilizzi Joint Institute for VLBI in Europe (schilizzi@jive.nl)

2. Three types of use • Transport of raw data from telescope(s) to data processing facility or database • distribution of data from processing facility or database to users • “mining’’ of databases

3. Transport of raw data • Required capacity is driven by radio telescope arrays • national scale e-MERLIN • LOFAR • European scale eEVN • global scale SKA

4. Hubble Deep Field • galaxies in a small area of sky radio source in the centre of the galaxy deep in the heart of the galaxy (zoom factor=1000) black hole?

5. Data mining in astronomy • Current Future • ASTROVIRTEL Astrophysical Virtual Observatory • dataset sizes 100’s gigabytes to 100’s terabytes at multiple sites • database access needs several gigabit/sec pan-European connectivity • distributed computing via the Grid e.g. astrometric satellite GAIA

6. eEVN: a real-time connected radio telescope as large as Europe plans to use the “Grid infrastructure” for - transporting raw data-streams from the telescopes to the central data processor at JIVE (via GÉANT) - real-time control of the distributed observing process - distributing processed data to scientists - data mining of archives to provide • new astronomical capabilities • operational reliability and flexibility

7. Science impact • wide bandwidth that is always available major increase in sensitivity for sources at the edge of the universe • wide bandwidth very high quality imaging • flexible, dynamic scheduling essential for making movies of variable sources like exploding stars

8. supernova in M81in 1993 (Bietenholz et al)

9. Operational impact • improved reliability • easier data logistics • flexible scheduling • lower operating costs • more effective network monitoring

10. eEVN pilot project: 2001 to 2004 • link 4 of the 14 EVN telescopes (and possibly 1 US telescope) to JIVE using as much off-the-shelf technology as possible • - bit rates up to 1 Gbps with latency < 1 second • - network monitoring and astronomical end-to-end testing for several periods of weeks at a time

11. Technology challenges • networking at multiple gigabit/sec via concatenated national, regional and pan-European research networks including Géant++. Quality of Service. • last mile connections to remote telescope sites • will Grid architectures and middleware be adequate for the expected data traffic and distributed computing? • networking at terabit/sec rates on the longer term

12. Summary • radio astronomy interferometry is a novel application of Grid capabilities for sustained data transfer at high bit rates from the telescopes to the central data processor • VLBI network characteristics: heterogeneous, multipoint to point, asymmetric • Challenges to be met: • - international connectivity at 1 Gbps - latency - cost (including last mile connections)

13. Radio telescope arrays • networks of radio telescopes spread over 100’s to 1000’s of km provide zoom lenses for astronomers • and gives them the most detailed pictures of distant stars and galaxies available to mankind • technique is called Interferometry

14. e-MERLIN • Dedicated optical fibres to connect telescopes to Jodrell Bank Observatory near Manchester • Sustained data rates of 30 Gbps/telescope to new data processor

15. LOFAR Configuration total data rate to centre ~ 20 terabit/sec Log-spiral distribution, 300 km

16. eEVN: European VLBI Network Data processing centre 32 - 256 Gbps China USA • Network characteristics • multi-point to point • asymmetric • heterogeneous 1-8 Gbps South Africa

17. how do we currently do this? VLBI configuration •  telescopes in different countries •  data recorded on “standard” tape at 1 Gbps and transported to a central location (300 tera-bytes/day) • data processor multiplies and adds at a rate of 1014 ops/sec Difference in time of arrival Recorder + atomic clock Recorder + atomic clock astronom- ical data at < 128 MB/s cross multiplication = signal detection

18. SKASquare Kilometer Array global collaboration technical concepts under evaluation operational in 2015 data rates up to terabit/sec

19. ESO Very Large Telescope • 4 x 8-m optical telescopes on Paranal in Chile • adaptive optics • IR spatial interferometry • all four elements in operation • HQ in Germany

20. GAIA Satellite and System • a high precision census of more than a billion stars in our Galaxy • Launch date: 2010 • Data rate: • 1 Mbs-1 sustained • 3 Mbs-1 downlink (1 ground station) • Design lifetime: 5 years • ESA only mission

21. GAIA Data Analysis: Concept and Requirements Capacity: ~100-500 Terabytes (20 TB of raw data) Overall system:centralised global iterative reduction approach Accessibility:quasi-random, in both temporal and object domains Processing requirements:entire task is ~1019 flop Data base structure:e.g. Objectivity (cf. Sloan, CERN, etc) Time critical:some results available in minutes (near-Earth asteroids, supernovae etc) Challenge: complexity of algorithms; inter-dependence of data; volume of data on-line