Download assorted slides

What is EXPReS?
• EXPReS = Express Production Real-time e-VLBI Service
• Three year project (March 2006-2009) funded by the European Commission
(DG-INFSO), Sixth Framework Programme, Contract #026642 EXPReS
• Funded at 3.9 million EUR
• International collaboration: 19 radioastronomy institutes and research and
education networks (NRENs) representing 14 countries on 6 continents
• 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 to the central correlator in the Netherlands
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Slide #1
EXPReS Partners
14 Countries, 6 Continents
Radio Astronomy Institutes
• Joint Institute for VLBI in Europe (Coordinator), The Netherlands
• Arecibo Observatory, National Astronomy and Ionosphere Center, Cornell University, USA
• Australia Telescope National Facility, a Division of CSIRO, Australia
• Institute of Radioastronomy, National Institute for Astrophysics (INAF), Italy
• Jodrell Bank Observatory, University of Manchester, United Kingdom
• Max Planck Institute for Radio Astronomy (MPIfR), Germany
• Metsähovi Radio Observatory, Helsinki University of Technology (TKK), Finland
• National Center of Geographical Information, National Geographic Institute (CNIG-IGN), Spain
• Hartebeesthoek Radio Astronomy Observatory, National Research Foundation, South Africa
• Netherlands Foundation for Research in Astronomy (ASTRON), NWO, The Netherlands
• Onsala Space Observatory, Chalmers University of Technology, Sweden
• Shanghai Astronomical Observatory, Chinese Academy of Sciences, China
• Torun Centre for Astronomy, Nicolaus Copernicus University, Poland
• Transportable Integrated Geodetic Observatory (TIGO), University of Concepción, Chile
• Ventspils International Radio Astronomy Center, Ventspils University College, Latvia
National Research and Education Networks (NRENs)
• AARNet, Australia
• DANTE, United Kingdom
• Poznan Supercomputing and Networking Center, Poland
• SURFnet, The Netherlands
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Slide #2
Participating Telescopes and Network Paths*
Image created by Paul Boven, JIVE. Satellite image: Blue Marble Next Generation courtesy of NASA Visible
Earth (visibleearth.nasa.gov). *Logical network paths.
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Slide #3
EXPReS Network Diagram
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Slide #4
Activities
#
PC
NA1
NA2
NA3
NA4
SA1
SA2
JRA1
Description
Project Coordinator
Management of I3
EVN-NREN Forum
eVLBI Science Forum
Public Outreach
Production Services
Network Provisioning
FABRIC
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Leader
Huib Jan van Langevelde, JIVE
T. Charles Yun, JIVE
John Chevers, DANTE
John Conway, Chalmers
Kristine Yun, JIVE
Arpad Szomoru, JIVE
Francisco Colomer, CNIG-IGN
Huib Jan van Langevelde, JIVE
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Slide #5
What is VLBI?
• Astronomy technique: Very Long Baseline Interferometry
• A radio telescope looks at an object in the sky and collects data to create an
“image” of the source.
• Multiple telescopes can view the same object simultaneously. The distance
between the telescopes is the baseline. The baseline can be compared to
building a single telescope with the diameter of this distance (sort of).
• The resolution increases with additional telescopes and longer baselines.
• The sensitivity of the image increases with the data collection rate at the
telescope.
• A central processor decodes, aligns and correlates the data for every possible
telescope combination.
• Result: images of cosmic radio sources with up to a hundred times better
resolution than images from the best optical telescopes
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Slide #6
The science of e-VLBI
Aperture Synthesis Imaging
Image Credits: Avruch and Pogrebenko
• A technique that uses a number of telescopes to simulate a much larger one.
A larger dish, real or simulated, improves image clarity and brightness. This
requires coordination between the telescopes and a supercomputer. Consider
the examples displaying aperture size, aperture distribution and image quality.
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Slide #7
Interferometry Makes a Virtual Telescope
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Slide #8
What is the correlator?
• Dedicated, purpose-designed and purpose-built hardware
• Synthesis imaging simulates a very large telescope by measuring
Fourier components of sky brightness on each baseline pair
• Decodes, aligns and correlates the data for every possible
telescope combination
• EVN MkIV data processor at JIVE
• custom silicon, 1024 chips
• Input data is 1 Gb/s max
• Around 100 T-operations/sec
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Slide #9
Interferometry
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Slide #10
What is e-VLBI?
• Electronic VLBI
• Instead of recording data and shipping disks to the central
processor, immediately transport data over networks and
correlate it in real-time.
• Benefits:
- eliminate weeks from the observation & correlation schedule
- monitor problems in data collection
- detect transient events and schedule near-immediate followon observations
- automate observation
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Slide #11
Traditional VLBI vs. e-VLBI
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Slide #12