LOFARLOFARThe Low-Frequency ArrayThe Low-Frequency Array
HeinoHeino Falcke FalckeLOFAR International Project ScientistLOFAR International Project Scientist
ASTRON, ASTRON, DwingelooDwingeloo(Netherlands Foundation for Research in Astronomy)(Netherlands Foundation for Research in Astronomy)
&&RadboudRadboud University, University, NijmegenNijmegen
Next generationradio telescope
• Telescope the size of theNetherlands plus Germany
• Frequencies: 30 - 240 MHz• 10% Square Kilometer Array (SKA)
prototype at low-frequencies• Interferometer baselines: 100 km
– European Expansion to 1000 km• Aperture array: Replace big dishes
by many cheap dipoles– 100 stations of 100 dipole antennas
+ extra sensors (geo+meteo)– No moving parts: electronic beam
steering– supercomputer synthesizes giant
dish• Current Funding: 74 M€• Two orders of magnitude
improvement in resolution andsensitivity
• Science applications: Big bang,astroparticles and the unknown
construction: 2006-2007
LOFAR - phased array telescope
LOFAR Key Science Programs
• Cosmology (Univ. Groningen, deBruyn)– Epoch of Reionization
• All-Sky Surveys (Univ. Leiden, Rottgering)– Star forming galaxies, AGN, Clusters, etc.
• Transient detection (Univ. Amsterdam,Wijers)– Everything that bursts and varies
• Astroparticle Phyiscs (Univ. Nijmegen,Kuijpers/Falcke)– Direct detection of cosmic rays– Cosmic rays & neutrinos impacting the moon
History of the Universe(condensed version)
Opaque
First Stars
Formation of Earth
Now
LOFAR
Invisible
Cosmological Redshift -Hydrogen line is seen at:
Big Bang Hydrogen
Sun & Earth
1.4 MHz 14 MHz 140 MHz1.4 GHz
protons
LOFAR Deep fieldsBillions of new sources
• LOFAR has a very largeField of View and be anideal survey telescope.
• LOFAR will be an all-skymonitor for detectingbursting (transient) radiosources.
• We expect to find > 100Million new sources:– stars & planets– star forming galaxies– active black holes– first objects in the universe– ???
Simulated radio deep field.
Radio image ofgiant radio galaxy
LOFAR simple-stationprototype:
500 Second All-Sky Map
LOFAR will have 1000 times higher resolution,100 times higher sensitivity, and 105 times
more integration time.
Transients with LOFAR-ITS:Jupiter and Lightning
L. Bähren (ASTRON)
Actual time span: 25 ms, 0.1ms/framePlaying time: 31 secFrequency: 23-26 MHz
Dynamic Spectrum
LOFAR Prototype Station (LOPES):detection of nanosecond radio flashes from
ultra-high energy elementary particles
All-Sky Movie of Radio Flash:200 ns duration
LOFAR Prototype Station:10 LOFAR Antennas
Falcke et al. (2005), Nature, Vol. 435, p. 313
Low-Frequency Observationsof the Moon
• Lunar radio emission isalso produced byCosmic Ray showersimpacting on the moon(Zas, Alvarez-Muniz)
• Low Frequencies havelonger attenuationlengths and samplelarger volume.
• Lunar observationsmay give best limit onsuper GZK CosmicRays!
Cosmic Rays
Scholten, et al. (2005, in prep.)
Ultra-High-Energy Cosmic Rays and Neutrinos:Low-Frequency Observations of the Moon
• Lunar radio emission isalso produced byCosmic Ray showersimpacting on the moon
• Low Frequencies havelonger attenuationlengths and samplelarger volume.
• Lunar observationsmay give best limit onsuper GZK CosmicRays!
Cosmic Rays
Scholten, et al. (2005, in prep.)
IBM Blue Gene/L “Stella” – theheart of LOFAR
• 27,4 Tflop
• ~ 12000 PCs
• Occupying 6 m2
• 150 KW power
consumption
• 0,5 Tbit/s input
• Now operational~1.7% slower than #1 in Europe (Barcelona) …
Dutch minister of science
Blue Gene
LOFAR Stations
• 96 Low Band Antenna’s• Distributed over ~60 m• Optimized for 30-80 MHz
• 96 High Band Tiles• 4x4 antenna’s• Disitributed over ~50m• Optimized ~115-240 MHz
Low Band Antennas
High Band Antennas
LOFAR Station Layout
Low BandHigh Band
60 m 50 m
Other Sensors
LOFAR Configuration
Virtual Core Phase I Layout
Land acquisition:200 out of 400 ha
secured
Network:Exloo – Groningen
link is in place
UV-CoverageVirtual Core 100km Array
Dec 80° Dec 50°
Dec 20° Dec 0°
Dec 80° Dec 50°
Dec 20° Dec 0°
LOFAR Basic Properties
European Expansion …
Current discussions:
Germany ~12 stations
UK ~2-3 stations
Italy ~2 stations
France ~1 station?
Poland ~1 station?
GLOW – German LongWavelength Consortium
German Roadmap
• Informal discussions with a group of universities (twice peryear)
• Writing of a White Paper• Presentation of WP to German Community• Individual grant applications by some institutes for stations
(two already honored)• Presentation of plan to to German ministries• Basic documents describing data rights and access,
involvement of German institutes are being developed• Memorandum of Understanding to create German Long
Wavelength (GLOW) consortium• Effelsberg will get first remote station this summer• Discussions with German supercomputing center (Jülich)
about support for German community (LOFAR science center)
Guidelines for remote stations
• The environment (now and in the future)– Fairly isolated– No power lines within 2 km– No highway within 500 mtr– No urban development within 500 mtr– No railroad, tramway within 2 km– No windmills within 2 km– No forest or high trees within 100 mtr. At south no trees within 500 mtr– No other radio interference sources in the neighborhood– A location in or at the fringe of a nature reserve is favorable but requires good
communication with environmentalists and nature organizations.• The location itself.
– Accessible by at least a macadam or sandy road.– 3 – 4 ha (200 x 200 mtr), however different sizes up to a minimal width of 120 mtr are
possible.– As horizontal as possible– Well drained, some water on the land during heavy rains is no probleme– With respect to the cables which shall be put into the ground look for a piece of land with
low potential for archeological findings.– In the Netherlands no iron fences will be used. However by using natural barriers (ditches,
swamps, hedges) entrance will be difficult.• Communication.
– The experience in the Netherlands learns that early, open en intensive communication withgovernmental organizations, public, neighbors etc will contribute to a fast acceptance of theproject and its location.
RFI/spectrum monitoring ofpotential remote station fields
• Monitoring full responsibility of ASTRON/LOFAR– Procedures
• Field requirements• RFI Monitoring• Field inspection
– Measurement equipment and transport– Datasets and analysis– Summary report
• Measurement data summary• Field inspection summary• Conclusions and recommendations
• Support/logistics required from hosts• Issue formal request for monitoring• Travel & hotel costs• Transport costs• Location coordinates, region, city, village, public or private property,….• Host representative at site location during monitoring• Request permission for spectrum measurements/monitoring in Germany
(approval required from national telecom agency)• communication with governmental organizations, public, neighbors etc
LOFAR Schedule
Jan 2004 2005 2006 2007 2008 2009 2010
CDRConnectionCore - Blue Gene/L Core Ring 2Inner ring
Ultimate Operation Initial Operation
Design & engineering
Procurement
Rollout and Integration
2020
CoreTestStation?
Core Station 1
• Operational May 1,2006 with “final”prototype hardware
• 96 dual-dipoleantennas:– grouped in 4 clusters– with 6 sub-stations– of 4 dipoles each– distributed over up to 1
km.• Emulate LOFAR with 24
micro-stations atreduced bandwidth orsingle station at full BW
Future Directions: Low-Frequency antennas at AUGER
Future directions:LOFAR on the Moon
• Below 10 MHz theatmosphere blocks radioemission.
• Man-made interferencecompletely swamps allsignals.
• No astronomy has everbeen done in this long-wavelength regime.
• The only location where thiscan be explored is the far-side of the moon.
• A single Ariane V couldbring a ~300m LOFARtelescope to the moon!
• Cooperation with EADSSpace Transportation.
EADS/ASTRON study
Summary
• LOFAR is well on track, first science already• It is the first serious aperture array and digital
software telescope in astronomy – excellentpreparation for SKA
• It will open up an almost forgotten frequency rangeand improve by two orders of magnitude
• Future:– European expansion– add multidisciplinary applications– add VLF antennas– put LOFAR antennas near AUGER – the world largest
cosmic ray detector in Argentina– there should be a southern LOFAR eventually …– put LOFAR on the moon …
New digital low-frequencyreceivers (LFFE) at Westerbork
3C147 with WesterborkFrequency: 163 MHzField of View: 20o x 20o
Integration: 12 hrs de Bruyn & Brentjens (2005)
Lightning with ITS
L. Bähren (ASTRON)
Actual time span: 25 ms, 0.1ms/framePlaying time: 31 secFrequency: 23-26 MHz
Dynamic Spectrum
LOFAR Network withGeophones + Infrasound
Precision Agriculture
• Use LOFAR infrastructure astestbed for sensor networksin agriculture
• Test case: Phytophthoradisease in potatoes
• Measure humidity in testfields
• Model spread of diseases incomputer
Þ Give farmer preciseinformation on usage ofpesticides, avoidingunnecessary spraying ofchemicals.
LOFAR top-level architecture:operations view
Catalogues
Modeling
Specificationand
Scheduling
Controland
Monitoring
GraphicalInterface
GraphicalInterface
Data Taking
CalibrationPre
Processing
Correlation /Beamforming
Fringe
Calibration
RFIMitigation
Storage
Archive
Export
OperatorScience OperationCenters
preparation
analysis
visualisation
Calibration
productcreation
Schedule
Central Processing
Raw dataCalibrated dataData productsMeta data
World Wide data AccessSensor fields
Internet & GRID
Archive
LOFAR top-level architecture:dataflow view
LOFAR Basic Parameters
Full Array Imaging: 32 MHzFull Array Imaging: 32 MHz
Core Imaging Mode: ~200 beams (4 MHz, 4kHz)Core Imaging Mode: ~200 beams (4 MHz, 4kHz)Expected Processing CapacityExpected Processing Capacity
100 MHz (10-90, 110-190 and 210-290 MHz)100 MHz (10-90, 110-190 and 210-290 MHz)80 MHz (170-230 MHz)80 MHz (170-230 MHz)
Digitized BandwidthDigitized Bandwidth
Virtual Core:Virtual Core:–– 3200 antennas 3200 antennas–– 32 stations 32 stations
–– baselines 100 m - 2 km baselines 100 m - 2 kmOutside Core:Outside Core:
–– 4500 antennas 4500 antennas–– 45 stations 45 stations–– baselines up to 100 km baselines up to 100 km
ConfigurationConfiguration
Full StokesFull StokesPolarizationPolarization
Low Band: 7700Low Band: 7700High Band: 7700 (4x4)High Band: 7700 (4x4)
Number of AntennasNumber of Antennas
Low Band: 30-80 MHzLow Band: 30-80 MHz
High Band: 110-240 MHzHigh Band: 110-240 MHzFrequency RangeFrequency Range