1. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE NEW USE for An old correlatoR Arpad Szomoru Joint Institute for VLBI in Europe

2. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Mark IV EVN Correlator Developed by international consortium: EVN institutes, MIT Officially inaugurated October 1998 Comparable correlators in use at Haystack Obs., US Naval Obs., MPIfR, JIVE Correlator boards in use at WSRT, SMA

3. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Basic specifications Input: No. of telescopes (N) 16 Array Observing frequencies: 329 MHz – 22 GHz Data bandwidth: 128 MHz per polarization (Right and Left-hand circular), divided into 8 bands. Channel bandwidths 0.5 MHz to 16 MHz. Data input rate: 1 Gbps per telescope Output: Integration time 1/4s (will become 1/32s with PCInt) 2048 spectral channels per baseline/band/polarization Data Output rate 6 MB/s (will become 80 MB/s with PCInt)

4. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE

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

7. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE EVN MkIV Correlator limits Integration time Cycle time of 0.015s (actually, 1/64th of a second) Spectral resolution 131072 complex lags per readout = 65536 spectral points per readout Divided over 32 products leads to 2048 spectral channels per product PCINT: Short for Post Correlator Integrator Capture the full output of the EVN MkIV correlator to disk Need to replace output datapath

8. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE The PCInt project High speed readout of the correlator was already prepared Via DSP powered serial port Need hardware and software to enable this Receiving end of serial port Gbit ethernet for transfer from correlator rack to data collection host Fast disk subsystem in order to support 160MByte/s (parallel RAID arrays in a Storage Area Network) Harro Verkouter

9. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Current situation CCC EEE (xk) DDD (xn) Switch FC Switch Correlator Board (x8) Raid Array (xm) RT System Ethernet Card C40 COMM VMEHigh Speed Serial SBC (x2) Correlator rack (x4) PCI 100TX 1000FX (x8) Fibre Channel

10. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Phase 0 CCC EEE (xk) DDD (xn) Switch FC Switch Correlator Board (x8) Raid Array (xm) RT System VME High Speed Serial Correlator rack (x4) 100TX 1000FX (x8) Fibre Channel Ethernet Card C40 COMM SBC (x2) PCI

11. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Phase 1 CCC EEE (xk) DDD (xn) Switch FC Switch Correlator Board (x8) Raid Array (xm) RT System VME High Speed Serial Correlator rack (x4) 100TX 1000FX (x8) Fibre Channel Ethernet Card C40 COMM SBC (x2) PCI

12. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Phase 2 CCC EEE (xk) DDD (xn) Switch Correlator Board (x8) Raid Array (xn) RT System VME High Speed Serial Correlator rack (x4) 100TX 1000FX (x8) 1000TX Ethernet Card C40 COMM SBC (x2) PCI

13. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Post-processing issues Huge data volumes 1hour @160MByte/s equals 560GBytes of data Use a cluster of nodes Need automated processing Use a processing pipeline Achieved 1/16s sampling, at 24 MB/s data output Users seem to be ready for 800 GB data-sets …

14. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Price recording media ($/GB)

15. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Data Acquisition Move from tape to disk recording Reliability Cost Bandwidth Efficiency e-VLBI: the next step No consumables Higher bandwidth Fast turn-around ToO support Disk based recording e-VLBI using fiber

16. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Why e-VLBI ? Reliability – real-time feedback to the telescopes Logistics – No media management Sensitivity – sustained data rates >> 1 Gbps possible… Rapid science results: Geodesy (Earth rotation rate) Precision spacecraft navigation Transient phenomena… GRBs, SNe etc.

17. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Why e-VLBI (cont) ? Target of Opportunity (ToO) capability: Dominated by VLBA currently… Reliability & Logistics  e-VLBI Sensitivity  e-VLBI Rapid science  e-VLBI Rapid publication  e-VLBI Optimal observing strategy (obs. freq., calibrators, telescope array) LOFAR Transients etc.  ToOs may become much more common  e-VLBI.

18. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE e-VLBI Proof-of-Concept Project DANTE/GÉANT Pan-European Network SURFnetDutch NREN GARR Italian NREN UKERNAUK NREN PSNC Polish NREN DFN German NREN KTHNOC/NORDUnet Nordic NREN Manchester UniversityNetwork application software JIVEEVN Correlator Westerbork telescopeNetherlands Onsala Space Observatory Sweden MROFinland MPIfRGermany Jodrell Bank UK TCfAPoland CNR IRA Italy

19. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE 0 SISI GRGR CZCZ IEIE LULU EEEE SKSK ILIL LTLTCYCY ESES HUHU ITIT FRFR UKUK BEBE NLNL DEDE SESE CHCH PTPT ATAT GEANT GEANT 2.5 G 1.2 G 622M 155 M BGBG LVLV RORO HRHR PLPL 45 M 34 M 310 M GÉANT: Access of NRENs to GÉANT EVN telescope

20. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE 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): 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.

21. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE EXPReS – major aims: Making e-VLBI an operational astronomical instrument: 16 telescopes connected to JIVE at 1 Gbps Robust real-time e-VLBI operations Transparent inclusion of e-MERLIN antennas within e-EVN Target of Opportunity Capability Future developments in e-VLBI >> 1 Gbps data transfer rates, extended LOFAR etc. distributed software correlation.

22. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE

24. Expanding the e-VLBI Network

25. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Network testing Use existing protocols on currently available hardware TCP maximal reliability Not really required Sensitive to congestion Lot of fine-tuning necessary And possible UDP connectionless Unaccountable Tailor made protocols? Lambda switching Internet weather Hard to quantify Hard to pinpoint bottlenecks

26. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE February 2005: network transfer test (BWCTL) employing various network monitoring tools involving Jb, Cm, On, Tr, Bologna and JIVE Network testing (2)

27. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE

28. 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

29. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE First open e-EVN Call for Proposals (March 2006) First Target of Opportunity Observations (May 2006, Cygnus X-3), Tudose et al. (in prep)…

30. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Current status Regular science runs at 128 Mbps with 6 European stations (24 hours) Arecibo sometimes participates at 32 Mbps Fringes from all European stations at 256 Mbps have been demonstrated, and, on single baselines, 512 Mbps

31. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Issues, Developments Convincing a correlator designed for tape technology to become real-time.. Operational improvements: Robustness Reliability Speed Ease Bandwidth Station feedback

32. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Ongoing New control computers (Solaris AMD servers) Cut down on (re-)start time Powerful code development platform Tightening up of existing code Other hardware upgrades: Upgrade existing connectivity from 6*1 Gbps to 16*1 Gbps (lightpaths) SX optics (fibres + NICs) Replacement of SU functionality: Mark5A→B: motherboards, memory, power supplies, serial links.

33. Next Gen. Correlator Workshop, Groningen, June 2006, A. Szomoru, JIVE Conclusions e-VLBI is changing the nature of VLBI Fast response, ToO capability better quality control, rapid data delivery New science, higher bandwidths Large fields of view Will allow the study of μJy sources Or many masers over a large star formation region Data archive will contain millions of weak sources EXPReS will realize an operational e-VLBI network distributed across 1000’s km – a true pathfinder for SKA.