Everything you wanted to know about e- VLBI and

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 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 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 2

Resolution: = 1. 22 /D This translates to about an arcminute or more even with the great, 100 m Effelsberg radio telescope at cm wavelengths. 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 3

Very Long Baseline Interferometry (VLBI) (Long long time ago, in a far away galaxy…) • Data recorded on magnetic 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) 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 4

Fringes 00101110101001010001 1001011101010011 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 5

• 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 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 6

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. NGC 4258 Miyoshi et al. (1995), Nature 373, 127 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 7

VLBI networks VLBA VERA 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 8

The European VLBI Network • Some of the worlds greatest radio telescopes, e. g. Effelsberg 100 m, Lovell 76 m 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 40 m (this year), telescopes in Sardinia, Latvia, Ireland China • Operating in three observing sessions per year, sometimes jointly with MERLIN (UK) and the VLBA (USA) – global VLBI • Observing wavelength ranges from 92 cm to 1. 3 cm • 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 Mk. IV correlator at JIVE http: //www. evlbi. org/ http: //www. jive. nl/ 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 9

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 (Mark 5 A) and Metsahovi Radio Observatory (PC EVN) • And it worked! • The EVN is fully disk operational (Mark 5 A) since early 2004 • Cheaper, off the shelf technology, perfect recording; data rate up to 1 Gbps http: //www. haystack. edu/tech/vlbi/mark 5/ 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 10

Paragi et al. (in prep. ) Just a flavour of what is possible: SNR in M 82 1 sigma noise 15 Jy/beam (limited by the noisy host galaxy) MERLIN archive 1. 6 GHz data, 1997 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 11

The sensitivity For six hours on-source integration in the C-band (6 cm) theoretical 1 sigma rms noises are VLBA, 128 Mbps: 80 Jy/beam HSA (VLBA+VLA 27+GBT), 128 Mbps: Predicted radio flux densities of ULXs in nearby galaxies, if these are powered by IMBHs 18 Jy/beam Full EVN, 1 Gbps: 8 Jy/beam Another example why the sensitivity limits are pushed so hard… Paragi et al. (2006) 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 12

The reliability • Disk recording is better quality, but it also provides a way to quickly check telescope performance: ftp tests • 2 -4 s 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… 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 13

VLBI observations timeline 1 -2 weeks Select your source Write an observing proposal 2 -3 months EVN PC makes a decision EVN scheduler provides a date … another 2 -3 months Observe with VLBI Data correlation well, why would you hurry? Data processing Publishing results THIS MUST CHANGE! 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 14

Target of Opportunity projects An example: the huge flare of SGR 1806 -20 • SGR 1806 -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, L 6 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 15

e-VLBI Proof-of-Concept Project (long, long time ago…) • • • • DANTE/GÉANT SURFnet GARR UKERNA PSNC DFN KTHNOC/NORDUnet Manchester University JIVE Westerbork telescope Onsala Space Observatory MRO MPIf. R Jodrell Bank TCf. A CNR IRA 2007 January 15 Pan-European Network Dutch NREN Italian NREN UK NREN Polish NREN German NREN Nordic NREN Network application software EVN Correlator Netherlands Sweden Finland Germany UK Poland Italy Everything you wanted to know about (e-)VLBI. . . and more 16

GÉANT: Access of NRENs to GÉANT NL DE BE CH SE HU IT 1. 2 G 2. 5 CZ AT G PL 34 M HR RO EVN telescope LV BG 310 M 55 LT SI M IE 1 45 M CY PT 2 M 0 GEANT ES 2007 January 15 GR 62 UK FR LU IL Everything you wanted to know about (e-)VLBI. . . and more SK EE 17

Network Topology for e. VLBI Gbit link Chalmers University of Technology, Gothenburg Network North-West Onsala Sweden Gbit link Torun Poland 150 Mbit link Jodrell Bank UK Dedicated Gbit link MERLIN Microwave link Cambridge UK 2007 January 15 Medicina Italy Everything you wanted to know about (e-)VLBI. . . and more Dwingeloo DWDM link 18 Westerbork Netherlands

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 To. O 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 Mk. IV 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 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 19

The first e-VLBI science result (line, 32 Mbps) MERLIN, March 2002 IRC+10420 2007 January 15 e-VLBI, September 2004 Richards et al. (2004) Everything you wanted to know about (e-)VLBI. . . and more 20

The first e-VLBI science result (continuum) • SN 2001 em was discovered on 15 September 2001 in UGC 11794 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 m. Jy radio source • EVN observations: Cm, Jb 2, On, Tr, Wb (128 Mbps), +Arecibo 300 m (64 Mbps) at 18 cm, on 2005 Mar 11 • Tentative detection (4. 5 ) of the first real faint target with e-VLBI Paragi et al. (2005), MSAIt 76, 570 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 21

What is EXPRe. S? • EXPRe. S = 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 realtime and connecting some of the largest and most sensitive radio telescopes on the planet http: //www. expres-eu. org/ 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 22

EXPRe. S 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 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 23

Telescope sites participating Image courtesy of Dr. Francisco Colomer 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 24

Activities # PC NA 1 NA 2 NA 3 NA 4 SA 1 SA 2 JRA 1 2007 January 15 Description Leader Project Coordinator Michael Garrett, JIVE Management of I 3 T. Charles Yun, JIVE EVN-NREN Forum John Chevers, DANTE e. VLBI Science Forum John Conway, Chalmers Public Outreach Kristine Yun, JIVE Production Services Arpad Szomoru, JIVE Network Provisioning Francisco Colomer, CNIG-IGN FABRIC Huib Jan van Langevelde, JIVE Everything you wanted to know about (e-)VLBI. . . and more 25

Telescopes connections (early 2007) Westerbork Netherlands Onsala Sweden 1 Gb/s 2. 5 Gb/s 155 Mb/s ? ? ? Soon available: Effelsberg, Yebes 40 m, Shanghai … 1 Gb/s JIVE Jodrell Bank UK e-MERLIN 2007 January 15 Torun Poland 1 Gb/s Cambridge UK Everything you wanted to know about (e-)VLBI. . . and more Medicina Italy 26

e-VLBI activities in 2006 • There are regular e-VLBI test observations in every six week (on average) • Normal operations at 256 Mbps (Cm, Jb 2, Mc, On, Tr, Wb) • Fringes to several telescopes at 512 Mbps, most recently to Mc • 24 h 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. html Science projects observed in 2006: Cyg X-3, 20 Apr/18 May, 128 Mbps, Tudose et al. GRS 1915, 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 M 81, 14 Dec, 256 Mbps, Brunthaler et al. INTEGRAL microquasar candidates, 14 Dec, Pandey et al. 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 27

First refereed journal papers: Rushton et al. (2007), MNRAS 374, L 47 Tudose et al. (2007), MNRAS… very soon Cyg X-3 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 28

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 6 cm), 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! 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 29

Future plans 16 Gbps connection to correlator at JIVE Dynamic scheduling – is this possible? Next generation (software? ) correlator …GRID processing 2007 January 15 Everything you wanted to know about (e-)VLBI. . . and more 30