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VLBI in Transition

VLBI in Transition. Arpad Szomoru Joint Institute for VLBI in Europe. EVN & JIVE. E uropean V LBI N etwork: collaboration of radio astronomy observatories in Europe, China, South Africa, USA

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VLBI in Transition

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  1. VLBI in Transition Arpad Szomoru Joint Institute for VLBI in Europe

  2. EVN & JIVE • European VLBI Network: collaboration of radio astronomy observatories in Europe, China, South Africa, USA • Central correlator facility in Dwingeloo, the Netherlands: Joint Institute for VLBI in Europe • Operations, user data • Network support • Visitor facilities • Technology development

  3. Principle of VLBI

  4. Price recording media ($/GB)

  5. Data Acquisition Disk based recording • Move from tape to disk recording • Reliability • Cost • Bandwidth • Efficiency • eVLBI: the next step • No consumables • Higher bandwidth • Fast turn-around • ToO support eVLBI using fiber

  6. e-VLBI Proof-of-Concept Project • DANTE/GÉANT Pan-European Network • SURFnet Dutch NREN • GARR Italian NREN • UKERNA UK NREN • PSNC Polish NREN • DFN German NREN • KTHNOC/NORDUnet Nordic NREN • Manchester University Network application software • JIVE EVN Correlator • Westerbork telescope Netherlands • Onsala Space Observatory Sweden • MRO Finland • MPIfR Germany • Jodrell Bank UK • TCfA Poland • CNR IRA Italy

  7. GÉANT: Access of NRENs to GÉANT 0 HU CH IT SE FR DE GR NL CZ BE GEANT AT 2.5 G 1.2 G GEANT UK PT 622M ES 310 M SI PL IE 155 M 34 M 45 M HR LU EE RO EVN telescope SK LV BG IL CY LT

  8. POC targets: • for the EVN and JIVE • Standards:- Protocols, parameter tuning, procedures at telescope and correlator. • New Capabilities:- Higher data rates, improved reliability, quicker response. • for GÉANT and the NRENs • To see significant network usage with multiple Gbit streams converging on JIVE. • Minimum is three telescopes (not including Westerbork) • Must be seen to enable new science and not just solve an existing data-transport problem • Real-time operation is seen as the ultimate aim, buffered operation accepted as a development stage.

  9. Current status: • JIVE: 6 lambdas via Netherlight, each capable of 1 Gbps; 16 * 1 Gbps soon • 1 Gbps connections to Westerbork, Torun, Onsala, Jodrell Bank, Medicina • 155 Mbps to Arecibo, 128 to Cambridge • Metsahovi being connected at 10 Gbps GE lines to correlator LX Optics converters Cisco ONS 15252 Optical Splitters Fibre pair from Amsterdam Correlator Interface

  10. First real-time eVLBI Image, 3 telescope observation of gravitational lens, May 2004 First eVLBI science observation, OH masers around IRC10420, Richards et al, Oct 2004 First broadband eVLBI science, detection of the Hypernova SN2001em, Paragi et al, astro-ph/0505468

  11. Parachute flight dynamics Huygens descent tracking • Detection of carrier signal during descent • Salvage of Doppler experiment • Building up experience with spacecraft tracking • Special purpose, extreme narrow band software correlator

  12. POC results • Demonstration of feasibility • Identification of problems • Has led to closer ties with networking community and generated political interest • Has laid the foundation for the next step forward (EXPReS)

  13. The next step… e-VLBI & EXPReS • I3 proposal to the EC (Communication & Network Development Call) • Ranked first out of 43 proposals; nearly fully funded to an amount of 3.9 MEuro. EXPReS = EXpress Production Real-time e-VLBI Service

  14. EXPReS aims • Upgrade EVN to e-EVN • 16 station real-time array • Help solve last mile problem • Including connections on a global scale • Software in field and correlator to become real real-time • Investigate/apply lambda switching • And look beyond 1 Gb/s • More capacity on digital sampling, more bandwidth • As being implemented for eMERLIN in UK • Hardware (PC-based) and protocols for transport • Correlator with more capacity: distributed correlation

  15. Expanding the e-VLBI Network

  16.  VLBI FoV x 100 6 arcmin [FWHP] Effelsberg beam Field of View limitation • Limited by tint • Time smearing • Shorter integrations • Enable wide field surveys • Study μJy sources • Discriminate AGNs • But, enormous increase of output data volume..

  17. PCInt, high speed read-out • VLBI field of view limited by correlator output rate • New hardware enabling high speed parallel read-out of correlator boards to dedicated cluster • Achieved 1/16s sampling • At 24 MB/s data output • Users seem to be ready for 800 GB data-sets…

  18. Archive • All output data on line • Several TB, dominated by few projects • Public one year after last epoch • Together with calibration info • All meta-data, schedules etc. • Quality control plots • Will need strategy to deal with data increase

  19. Advanced Long Baseline User Software • RadioNet project JBO, MPIfR, ASTRON • Addresses calibration issues for radio-interferometry, in particular VLBI • Ionosphere, troposphere • Improved data product with Tsys and PC • Data distribution selection tools • Parallelization for large data sets • eMERLIN, EVN and WSRT will produce user data sets of up to 1TB • Focus on high-level parallelization • Wide band and wide field imaging

  20. Conclusions • eVLBI is changing the nature of VLBI • Fast response, ToO capability • better quality control, rapid data delivery • New science, higher bandwidths • Large fields of view • Allows one to study μJy sources • Or many masers over a large star formation region • Data archive will contain millions of weak sources • Introduction of new algorithms • Improved calibration • Methods to deal with vast data sets

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