e-EVN and VSOP-2 Zsolt Paragi (JIVE), for the EXPReS project

2008 May 14-16VSOP-2 meeting, BonnSlide #2 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 EXPReS 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 14-16VSOP-2 meeting, BonnSlide #3 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 # 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 Initiated and formerly coordinated by Mike Garrett, now coordinated by Huib J. van Langevelde

2008 May 14-16VSOP-2 meeting, BonnSlide #4

2008 May 14-16VSOP-2 meeting, BonnSlide #5 e-VLBI for science Regular e-VLBI test observations in every six week (on average) 24h 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 ToO and triggered projects May trigger proposals 24h hours before observations Science operations so far at 1.6 and 5GHz at Mbps (Cm, Jb2, Mc, On, Tr, Wb) More info at

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

2008 May 14-16VSOP-2 meeting, BonnSlide #7 EXPReS 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 Mark5A software was not stable enough, modified software Station Unit crashes: rewrote software, SU reboot during correlation job is now possible; Mark5B will retire SUs Station Mark5As may be rebooted from JIVE without stopping the correlation job Longest uninterrupted e-VLBI job is 12h 43m! 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 14-16VSOP-2 meeting, BonnSlide #8 Test results 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. Happy JIVE staff in Dwingeloo

2008 May 14-16VSOP-2 meeting, BonnSlide #9 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 SN1987A

2008 May 14-16VSOP-2 meeting, BonnSlide #10 And with VLBI… Highest resolution image of SN1987A so far (first VLBI!) – not bad for a three telescope array. Countours shows an earlier ATCA image. Various fits to the data to measure the size of the expanding remnant. Tingay et al., (in prep.)

2008 May 14-16VSOP-2 meeting, BonnSlide #11 Tests in 2008, happy new year for EXPReS 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 14-16VSOP-2 meeting, BonnSlide #12 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 (6m dish in Chile) fringes at 64 Mbps

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

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

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

2008 May 14-16VSOP-2 meeting, BonnSlide #16 Science in 2008 Arp299 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 ToO – the first ToO observations on unscheduled date. All of these at 512 Mbps. First pipeline image from 4h of data produced during the experiment.

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

2008 May 14-16VSOP-2 meeting, BonnSlide #18 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 14-16VSOP-2 meeting, BonnSlide #19 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 ToO) 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).