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Everything you wanted to know about (e-)VLBI… …and more

Everything you wanted to know about (e-)VLBI… …and more. Zsolt Paragi, JIVE. Abstract. I will talk briefly about the Very Long Baseline Interferometry (VLBI) technique and what we can do with it. The European VLBI Network (EVN) will be shortly introduced. Then I will describe

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Everything you wanted to know about (e-)VLBI… …and more

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  1. Everything you wanted to know about (e-)VLBI… …and more Zsolt Paragi, JIVE

  2. Abstract I will talk briefly about the Very Long Baseline Interferometry (VLBI) technique and what we can do with it. The European VLBI Network (EVN) will be shortly introduced. Then I will describe the recent e-VLBI developments at JIVE. Science examples will be mixed in all over the talk. The following 30 minutes will be about RESOLUTION SENSITIVITY RAPID RESPONSE SCIENCE Everything you wanted to know about (e-)VLBI ...and more

  3. Resolution: = 1.22/D This translates to about an arcminute or more even with the great, 100m Effelsberg radio telescope at cm wavelengths. Everything you wanted to know about (e-)VLBI ...and more

  4. Very Long Baseline Interferometry (VLBI) (Long long time ago, in a far away galaxy…) • Data recorded on mag- • netic tapes • Later processed in a • correlator • This need thorough • knowledge of geometry • and very precise timing • information • Earth diameter limits • resolution (tipically mas) • Number of telescopes, • their diameter and • performance, as well as • the recording rate limits • the sensitivity • Magnetic tapes could do • 256 Mbps (512 with two • heads) Everything you wanted to know about (e-)VLBI ...and more

  5. Fringes 001011101010011001010001 100101111001011101010011 Everything you wanted to know about (e-)VLBI ...and more

  6. An interferometer measures the Fourier-components of the sky brightness distribution • As the Earth rotates, the projected baselines sample various spatial frequencies, that • provide information on the target source structure at various angular scales • We measure the fringe phase • and amplitude at each of these • sampled spatial frequencies • The data are pre-processed, • and a “dirty image” is formed • by Fourier transform • Further calibration of fringe • amplitudes and phases is done • parallel to the deconvolution • of this dirty image Everything you wanted to know about (e-)VLBI ...and more

  7. And what can I do with this? • Objects with fairly compact structures and • astrometry studies: • e.g. parallax measurements up to several kpc • ( < 0.001 arcsecond) • may resolve nearby stars and their environment, • (0.1 AU resolution at 100 pc) • Active Galactic Nuclei, (compact jets of several • pc have mas structures at even high redshifts) • black hole astrophysics, gravitational lenses and • much more… • Geodetic VLBI: tectonics on Earth, time service • end EOPs, International Celestial Reference • Frame (ICRF) And of course spectral line observations of HI, and MASERs of stellar and extragalactic origin. NGC4258 Miyoshi et al. (1995), Nature 373, 127 Everything you wanted to know about (e-)VLBI ...and more

  8. VLBI networks VLBA VERA Everything you wanted to know about (e-)VLBI ...and more

  9. The European VLBI Network • Some of the worlds greatest radio telescopes, e.g. Effelsberg 100m, Lovell 76m telescopes, • Westerbork Synthesis Radio Telescope • Outside Europe includes Hartebeesthoek (South Africa), Urumqi and Shanghai (China) • Several telescopes are being built that will join the EVN: Yebes 40m (this year), telescopes • in Sardinia, Latvia, Ireland and China • Operating in three observing sessions per year, sometimes jointly with MERLIN (UK) and • the VLBA (USA) – global VLBI • Observing wavelength ranges from 92cm to 1.3cm • The most sensitive standalone VLBI array (the so-called High Sensitivity Array formed • occasionally by the VLBA, VLA, GBT and maybe Arecibo competes with it) • The data are correlated in the EVN MkIV correlator at JIVE http://www.evlbi.org/ http://www.jive.nl/ Everything you wanted to know about (e-)VLBI ...and more

  10. The end of the tape era • Tape recording had limited performance (parity • errors), and • limited data rate (256 Mbps; 512 Mbps with • two write heads). • Tapes were expensive • Tape playback units were not easy to maintain • Disk based recording systems were developed at • Haystack (Mark5A) and Metsahovi Radio • Observatory (PC EVN) • And it worked! • The EVN is fully disk operational (Mark5A) • since early 2004 • Cheaper, off the shelf technology, perfect • recording; data rate up to 1 Gbps • http://www.haystack.edu/tech/vlbi/mark5/ Everything you wanted to know about (e-)VLBI ...and more

  11. Just a flavour of what is possible: SNR in M82 1 sigma noise 15 Jy/beam (limited by the noisy host galaxy) Paragi et al. (in prep.) MERLIN archive 1.6 GHz data, 1997 Everything you wanted to know about (e-)VLBI ...and more

  12. The sensitivity For six hours on-source integration in the C-band (6cm) the theoretical 1 sigma rms noises are VLBA, 128 Mbps: 80 Jy/beam HSA (VLBA+VLA27+GBT), 128 Mbps: 18 Jy/beam Full EVN, 1 Gbps: 8 Jy/beam Another example why the sensitivity limits are pushed so hard… Predicted radio flux densities of ULXs in nearby galaxies, if these are powered by IMBHs Paragi et al. (2006) Everything you wanted to know about (e-)VLBI ...and more

  13. The reliability • Disk recording is better quality, but it • also provides a way to quickly check • telescope performance: ftp tests • 2-4s data at 256 Mbps  64-128 MB files, • may be transferred through the Internet! • Data processed by a software correlator • developed in NICT, Japan • Since late 2004 there are regular ftp tests • during EVN sessions. • The software correlator runs on a PC cluster • Feedback to telescopes used to take at least • a week, now it is a matter of minutes • OK, let us see what else can we improve… Everything you wanted to know about (e-)VLBI ...and more

  14. VLBI observations timeline 1-2 weeks 2-3 months 2-3 months Select your source Write an observing proposal EVN PC makes a decision EVN scheduler provides a date    … another 2-3 months well, why would you hurry? Observe with VLBI Data correlation Data processing Publishing results    THIS MUST CHANGE! Everything you wanted to know about (e-)VLBI ...and more

  15. Target of Opportunity projects An example: the huge flare of SGR1806-20 • SGR1806-20 is a soft gamma-ray repeater a • neutron star with very strong magnetic fields, • a magnetar • Produced the greatest explosion witnessed by • humans in our Galaxy, on 27 December 2004 • Observations with various instruments, also • VLBI (with the VLBA array) • Could not image reliably because of lack of • known calibrator in the vicinity of the target! • Is there a way to do these projects more efficiently? • Is there a way to get the data and analyze them • quickly??? Fender et al. (2005), MNRAS 367, L6 Everything you wanted to know about (e-)VLBI ...and more

  16. e-VLBI Proof-of-Concept Project (long, long time ago…) • 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 Everything you wanted to know about (e-)VLBI ...and more

  17. 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 Everything you wanted to know about (e-)VLBI ...and more

  18. Network Topology for eVLBI Gbit link Chalmers University of Technology, Gothenburg Network North-West OnsalaSweden Gbit link TorunPoland 150Mbit link Jodrell BankUK WesterborkNetherlands DedicatedGbit link MERLIN Microwave link Dwingeloo DWDM link CambridgeUK MedicinaItaly Everything you wanted to know about (e-)VLBI ...and more

  19. First real-time eVLBI Image The beginning of e-VLBI in Europe • With e-VLBI one could continuously monitor telescope performance • Results would be available almost immediately • Could be more flexible to ToO projects • May make quick decisions about the use of a calibrator, or follow-up observations • The EVN would be more competent in ‘hot topic’ science • Had to prove that the EVN MkIV correlator can be upgraded to realtime operations • Had to prove that the research networks can cope with the network load • Had to test and tune transfer protocols • First tests were promising, and then came the first real e-VLBI image in 2004 Everything you wanted to know about (e-)VLBI ...and more

  20. The first e-VLBI science result (line, 32 Mbps) e-VLBI, September 2004 MERLIN, March 2002 IRC+10420Richards et al. (2004) Everything you wanted to know about (e-)VLBI ...and more

  21. The first e-VLBI science result (continuum) • SN2001em was discovered on 15 September 2001 in UGC11794 galaxy (Pepenkova 2001). • Redshift z~0.02 corresponding to a distance of 80~Mpc. • Filippenko and Chornok (2001) classified it as type Ib/c, most likely Ic. • Exceptional radio and X-ray luminosities • (off axis GRB, developing late radio emission • due to jet break?), • Not quite a 1 mJy radio source • EVN observations: Cm, Jb2, On, Tr, Wb (128Mbps), +Arecibo 300m (64 Mbps) • at 18cm, on 2005 Mar 11 • Tentative detection (4.5 ) of the first real faint target with e-VLBI • Paragi et al. (2005), MSAIt 76, 570 Everything you wanted to know about (e-)VLBI ...and more

  22. What is EXPReS? • EXPReS = Express Production Real-time e-VLBI Service • Three year project, started March 2006, funded by the European Commission (DG-INFSO), Sixth Framework Programme, Contract #026642 • Objective: to create a distributed, large-scale astronomical instrument of continental and inter-continental dimensions • Means: high-speed communication networks operating in real-time and connecting some of the largest and most sensitive radio telescopes on the planet http://www.expres-eu.org/ Everything you wanted to know about (e-)VLBI ...and more

  23. EXPReS Partners • Joint Institute for VLBI in Europe (coordinator) • AARNET Pty Ltd., Australia • ASTRON, The Netherlands • Centro Nacional de Informacion Geografica, Spain • Chalmers Tekniska Hoegskola Aktiebolag, Sweden • Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia • Cornell University, USA • Delivery of Advanced Network Technology to Europe Ltd. (DANTE), UK • Instituto Nazionale di Astrofisica, Italy • Instytut Chemii Bioorganicznej PAN, Poland • Max Planck Gesellschaft zur Foerderung der Wissenschaften e.V., Germany • National Research Foundation, South Africa • Shanghai Astronomical Observatory, Chinese Academy of Sciences, China • SURFNet b.v., The Netherlands • Teknillinen Korkeakoulu, Finland • The University of Manchester, UK • Universidad de Concepcion, Chile • Uniwersytet Mikolaja Kopernika, Poland • Ventspils Augstskola, Latvia Everything you wanted to know about (e-)VLBI ...and more

  24. Telescope sites participating Image courtesy of Dr. Francisco Colomer Everything you wanted to know about (e-)VLBI ...and more

  25. Activities # Description Leader PC Project Coordinator Michael Garrett, JIVE NA1 Management of I3 T. Charles Yun, JIVE NA2 EVN-NREN Forum John Chevers, DANTE NA3 eVLBI Science Forum John Conway, Chalmers NA4 Public Outreach Kristine Yun, JIVE SA1 Production Services Arpad Szomoru, JIVE SA2 Network Provisioning Francisco Colomer, CNIG-IGN JRA1 FABRIC Huib Jan van Langevelde, JIVE Everything you wanted to know about (e-)VLBI ...and more

  26. WesterborkNetherlands OnsalaSweden ? 1Gb/s 1Gb/s ? ? ? ? 2.5Gb/s 155Mb/s 1Gb/s JIVE TorunPoland 1Gb/s Jodrell BankUK Cambridge UK e-MERLIN MedicinaItaly Telescopes connections (early 2007) Soon available: Effelsberg, Yebes 40m, Shanghai … Everything you wanted to know about (e-)VLBI ...and more

  27. e-VLBI activities in 2006 • There are regular e-VLBI test observations in every six week (on average) • Normal operations at 256 Mbps (Cm, Jb2, Mc, On, Tr, Wb) • Fringes to several telescopes at 512 Mbps, most recently to Mc • 24h time is pre-allocated for science observation during each e-VLBI test • Observing proposals may be submitted two weeks before the advertised date • More info at http://www.evlbi.org/evlbi/evlbi.html • Science projects observed in 2006: • Cyg X-3, 20 Apr/18 May, 128 Mbps, Tudose et al. • GRS1915, 20 Apr, 128 Mbps, Rushton et al. • LSI +61.303, 256 Mbps, 26 Oct, Perez-Torres et al. • Algol, 26 Oct/14 Dec, 256 Mbps, Paragi et al. • Calibrators near M81, 14 Dec, 256 Mbps, Brunthaler et al. • INTEGRAL microquasar candidates, 14 Dec, Pandey et al. Everything you wanted to know about (e-)VLBI ...and more

  28. First refereed journal papers: Rushton et al. (2007), MNRAS 374, L47 Tudose et al. (2007), MNRAS… very soon Cyg X-3 Everything you wanted to know about (e-)VLBI ...and more

  29. Want to propose e-VLBI observations? • e-VLBI proposals must be submitted by e-mail to the EVN PC; a web proposal • tool will be available in a couple of days… • e-VLBI proposals are just like other EVN proposals, but you must take additional care to • justify properly why urgency is needed (target of opportunity, e.g. known transient flares, • or need to check calibrators quickly for another project, taking part in an observational • campagin) • give accurate coordinates (sub-arcsecond accuracy) • specify all the details of the proposed observations – schedule will be made by JIVE staff • contact Bob Campbell (campbell@jive.nl), to find out if preferred correlation mode is OK • keep in mind the limited resolution (~6*8 mas at 6cm), uv-coverage and sensitivity • at the moment • When 512 Mbps is possible and Effelsberg joins the array, the sensitivity will improve • greatly; with Shanghai joining during 2007, the resolution will be better as well • Be ready to travel to JIVE for quick data processing • Think creatively, find projects that make appropriate use of this unique service! Everything you wanted to know about (e-)VLBI ...and more

  30. Future plans 16 Gbps connection to correlator at JIVE Dynamic scheduling – is this possible? Next generation (software?) correlator …GRID processing Everything you wanted to know about (e-)VLBI ...and more

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