eEVN and VSOP2 Zsolt Paragi JIVE for the

e-EVN and VSOP-2 Zsolt Paragi (JIVE), for the EXPRe. S project

Relevance The EVN will be a key partner to VSOP-2. Current developments will have a direct impact on VSOP-2 operations. Talk This talk will focus on data transfer and network reliability related issues. The EXPRe. S e-VLBI project will be introduced. Challenges, solutions, and the most recent results will be shown. Will close with a few thoughts about the (e-)EVN and VSOP-2. 2008 May 14 -16 VSOP-2 meeting, Bonn 2

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 • Initiated and formerly coordinated by Mike Garrett, now coordinated by Huib J. van Langevelde http: //www. expres-eu. org/ 2008 May 14 -16 VSOP-2 meeting, Bonn 3

2008 May 14 -16 VSOP-2 meeting, Bonn 4

e-VLBI for science • Regular e-VLBI test observations in every six week (on average) • 24 h time is pre-allocated for science observation during each e-VLBI test • Observing proposals submitted up to normal deadlines - short projects, preparing for normal EVN runs - spectral line experiments - continuum, including To. O and triggered projects • May trigger proposals 24 h hours before observations • Science operations so far at 1. 6 and 5 GHz at 32 -512 Mbps (Cm, Jb 2, Mc, On, Tr, Wb) • More info at http: //www. evlbi. org/evlbi. html 2008 May 14 -16 VSOP-2 meeting, Bonn 5

Science projects in 2006/2007 • Cyg X-3, 20 Apr/18 May, 128 Mbps, Tudose et al. • GRS 1915+105, 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. • “double header” run, 15 XRBs, 29 Jan, Rushton & Spencer • Calibrators, 21 Feb, 256 Mbps, Tudose et al. • J 2020+3631 microquasar candidate, 28 Mar, 256 Mbps, Martí et al. • Cyg X-3, 12 -13(? ) Jun, 256 Mbps, Tudose et al. • Stellar maser search, 22 -23 Aug, 32 Mbps, Langevelde et al. • INTEGRAL source redo, 6 -7 Sep, 256 Mbps, Pandey et al. • Type Ib/c SN 2007 gr, 6 -7 Sep, 256 Mbps, Paragi et al. 2008 May 14 -16 VSOP-2 meeting, Bonn 6

EXPRe. S challenges and solutions • TCP protocol operating on normal network limited operations to 256 Mbps even within Europe - lightpathes to telescopes (dynamically allocated in the future? ) - UDP-based protocol developed • Mark 5 A software was not stable enough, modified software • Station Unit crashes: rewrote software, SU reboot during correlation job is now possible; Mark 5 B will retire SUs • Station Mark 5 As may be rebooted from JIVE without stopping the correlation job • Longest uninterrupted e-VLBI job is 12 h 43 m! • 1024 Mbps formatted data over 1 Gbps equipment does not work: drop few percent of the packages (but keep headers) • Connection very limited to some telescopes: drop subbands (being tested at the moment) 2008 May 14 -16 VSOP-2 meeting, Bonn 7

Test results Happy JIVE staff in Dwingeloo APAN live demo in China (August 2007): fringes between EU telescopes and Shanghai and Mopra. Demonstrated feasibility of global e-VLBI observations with an ad-hoc array. Note Australian data format was converted in real-time. 2008 May 14 -16 VSOP-2 meeting, Bonn 8

Science results from the ‘Oz-demo’ ATCA, Mopra and Parkes observations at 512 Mbps, correlated at JIVE. Target: the nearby supernova in the LMC, only visible from the South. One of the breathtaking Hubble Space Telescope images of SN 1987 A 2008 May 14 -16 VSOP-2 meeting, Bonn 9

And with VLBI… Various fits to the data to measure the size of the expanding remnant. Tingay et al. , (in prep. ) Highest resolution image of SN 1987 A so far (first VLBI!) – not bad for a three telescope array. Countours shows an earlier ATCA image. 2008 May 14 -16 VSOP-2 meeting, Bonn 10

Tests in 2008, happy new year for EXPRe. S First 1 Gbps e-EVN image with packed dropping. Cm, Jb, Mc, Tr, Wb participated. Not all had fringes in all subbands, but from the data transfer point of view it was a 1 Gbps result. 2008 May 14 -16 VSOP-2 meeting, Bonn 11

New e-telescopes every week! • Effelsberg joins the e-EVN on 1 st of April 2008, in all subbands up to 1 Gbps data rates. • Most recently Hartebeesthoek live demo fringes at 32 Mbps • …and Arecibo-TIGO (6 m dish in Chile) fringes at 64 Mbps 2008 May 14 -16 VSOP-2 meeting, Bonn 12

Gentlemen pleased in South Africa 2008 May 14 -16 VSOP-2 meeting, Bonn 13

…and in JIVE This was a few minutes with fringes between Arecibo and Hart 2008 May 14 -16 VSOP-2 meeting, Bonn 14

Science highlight from 2007 Supernova 2007 gr detected on 6 Sep. Just ~400 u. Jy! 256 Mbps, no Ef. First ATel message from the e-EVN. Followed-up with a global VLBI array. Paragi et al. (2007) 2008 May 14 -16 VSOP-2 meeting, Bonn 15

Science in 2008 • Arp 299 SNe by Perez-Torres et al. in April; very robust operations (longest correlation job at JIVE; see MERLIN image of target and e-VLBI throughput graph to the right ) • Followed by the first ever triggered e. EVN triggered project: Cyg X-3 accretion disk state change (Tudose et al. ) ATel publication. • In May Cyg X-3 flared, three epochs e -EVN To. O – the first To. O observations on unscheduled date. All of these at 512 Mbps. First pipeline image from 4 h of data produced during the experiment. 2008 May 14 -16 VSOP-2 meeting, Bonn 16

JIVE software correlator • JIVE software correlator replaced NICT (CRL) software for ftp fringe tests. • Doing R&D on GRID-based software correlation. 2008 May 14 -16 VSOP-2 meeting, Bonn 17

e-EVN and VSOP-2: data transfer • The e-EVN will aim for 10 Gbps operations, which is feasible already now from networking point of view. VSOP-2 will be limited to 1 Gbps. • The EVN will not abandon disk recording completely, which ensures operations with VSOP-2 (needs accurate orbit for correlation, thus cannot be real-time); but data may be put to the network immediately instead of local storage at the telescopes. • Central data storage and distributed software correlation on the GRID is a possibility. Data acquisition system difference is not a problem, but software must be there to translate data on the fly. 2008 May 14 -16 VSOP-2 meeting, Bonn 18

e-EVN and VSOP-2: operations • Although real-time space VLBI is not possible, must establish a quick fringe checking mechanism like the ftp tests in the EVN. This will allow monitoring of the array performance. • Automatic data pipeline and easy access through data archive like in the EVN would help space VLBI users. • e-EVN quick fringe-test results prior to VSOP-2 survey (or To. O) observations may be desirable; note that because the candidate sources are very variable at these frequencies a pre-launch survey may not be useful at all. Even total flux density measurements prior to VSOP-2 observations will not guarantee source compactness (although likely will be sufficient most of the time). 2008 May 14 -16 VSOP-2 meeting, Bonn 19