1. ● Radio telescope arrays – 5 - 5000 km diameter – Resolution arcmin to micro-arcsec at radio wavelengths ● Similar (baseline/ wavelength) for other regimes – IR - mm e.g. IRAM, ALMA (Gary Fuller) – Optical e.g. VLTI Access to Aperture Synthesis Data through the VO Anita Richards, AVO, JBO, University of Manchester

2. M82 - MERLIN Muxlow/Pedlar/Wills EVN Interferometry - strengths.... ● Milli-arcsec resolution ● Sub-mas astrometry, define ICRF ● Multi-scale images from visibility data ● Radio (and some other) – Non-thermal emission – (Almost) no extinction – 10 -7 spectral resolution – Polarization – Intrinsic wide field of primary beam (MERLIN >10 4 synthesised beam) 3C264 Lara et al MERLIN+EVN EVN MERLIN

3. Obstacles and Solutions Visibility data sets >Gb already Fourier transforms expensive Most sensitive images lose spatial/time/spectral resolution Potential field of view ~10 8 pixels =10 2 screen dumps Incomplete apertures - missing angular scales Requires specialised software, intensive user support PSR timing, light curves, modelling visibilities etc. Remote data reduction Parallel processing Offer choice of processing routes Image required region /resolution on demand Combine multi-array data (&/or upgrade interferometer!) Pipeline processing, offer simplified user options, &/or remote use of software Store (reversibly) calibrated visibility data Many VO Solutions!

4. Radio interferometry archives MERLIN+HST 2001 B 1993: Pre-RSN 2001: RSN A Radio supernova Colina et al. 2001 Current on-line variety: ● Lists of observed sources ● Calibration source plots ● Experiment information ● Retrospective pipelining to FITS images and data ● On-line on-demand imaging – from visibility archive – surveys (image cutout) ● Pipelining new data into archive for user access ● Integration of archives/ major catalogues into CDS Archive extraction

5. Next generation interferometers ● e-MERLIN 2005 – Fibres: 30 Gb/s x 6 telescopes [2 PB/day] – Correlator: 0.5 TB/day ● eVLA 2006 ● ALMA 2007 ● VLTI, e-EVN, SKA etc. ● (e)-EVN incremental – Disc recording soon – Data-rate ~e-MERLIN (for starters...) MERLIN e-MERLIN

6. Astronomical technology drivers ● Astronomy data sets – massive – free (mostly) ● Interesting to research/ commerce organisations – DB providers – software engineers, – ontologists – network providers ● eEVN connections via Géant plausible (DANTE) – local loops going in now – Real-time demo by 2004 ● Fast response to – variability – RSNe etc ● More data! ● Fibres available to VO?

7. European Topology - UK SuperJANET4 CERN Manchester /Jodrell NL SURFnet iGrid 2002 JIVE

8. Facility-based data centres? ● MERLIN archive will – provide an increasing amount of on-line data – impliment (processor speed/staffing) limited image server – upgrade database (very soon) – continue access via CDS – become AstroGrid data centre, test/impliment web and grid services (soon) ● e-MERLIN will provide an archive – open and restricted access as appropriate – simplified and remote data processing – all processing reversible, data recycling in many forms ● As will ALMA, SKA etc. etc (locations tbd).

9. VO-linked data centres 3 ● Interferometry data centre(s) could – speed up implimentation of current plans e.g. ● access to spectral line data/cubes, chemical DBs? ● explore exploitation of parallel processing – become fully VO-compliant ● develop standards for interferometry data providers – mirror or link or otherwise provide interface for ● any interferometry data ● on-demand user processing – integration with other VO data and facilities e.g. ● multi-wavelength comparison ● authentication ● high-resolution image alignment (commonest cases)