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Low-Frequency Array LOFAR
More than an EoR Telescope ...
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• General
• simple antennas, but many 25000 in the full
  LOFAR design.
• spread over an area of ultimately 350 km in
  diameter.
• phase 1 15000 antennas funded, max. baselines
  100 km
• data rate many Tbits/sec, processing power
  T-FLOPS.

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• LOFAR Phase 1
• compact core
• 45 remote stations
• equipped with 100 high-band antennas, 100
  low-band antennas and
• 13 three-axis vibration sensors (geophones),
  
• 3 micro-barometers (for infrasound detection)
  
• several auxiliary systems (weather
  monitoring, and GPS time/position
  measurements)

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• Antenna signals
• handled by a broad-band integrated receiver and
  digital processing system
• direct conversion of a 100 MHz band
• each receiver connected to a low- and a
  high-band antenna
• 100 MHz signal will be buffered for 1 sec (CR)
  detection and transient processing)
• first digital processing step 256 kHz subbands
  formed
• only a subset of these bands is further
  processed
• max. total bandwidth for further processing 32
  MHz
• each remote station delivers
• single dual-polarization beam at 32 MHz,
• or 8 dual polarization beams at 4 MHz,

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• Software
• extensive System Health Management function
  (self-diagnosing and possibly self-healing)
• very large data streams
• e.g. 6 TB of raw visibility data for an 8-beam,
  4 hour synthesis observation, after integration
  for 1 sec and over 10 kHz
• 1 month of observing in this mode 1 PetaByte
  of data
• systematic long-term storage extremely
  expensive!
• resulting output data rate is 2 Gb/s
  secondary filtering stage (to 1-kHz channels) is
  done in the Central Processing system
• 2 ? 16 bits ? 2 ? 32 MHz
• poln. Amp. phase bandwidth

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• Central processing sytem
• input section of Central Processor dimensioned
  such that 32 core and 50 remote stations can be
  accommodated simultaneously at their full
  bandwidth
• core of CEP IBM BlueGene/L (Groningen), 27.4
  Teraflops
• BG/L surrounded by PC clusters with infiniband
  backbones

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• Astronomy application modes
• synthesis imaging
• transient detection (probably using correlation
  of large numbers of low- bandwidth beams)
• tied array beam-forming
• antenna-based buffering of 1 sec at
  full-digitised bandwidth and limited
  detection/triggering (in particular for UHECR
  events) at station level

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Ionosphere !
2 sources observed with GMRT at 150 MHz 8 hours
of data, one frame 1 minute (de Bruyn et al.)
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• LOFAR in brief
• 15000 (25000) dipoles clustered in ? 100
  stations ? simple frontend hardware, but
  complex digital correlation ...
• ? 400 km across
• frequency coverage 10 MHz - 200 MHz
• collecting area ? 1 km2
• ?b 2? - 40?
• correlation via optical fibres
• fully digital!
• low costs (? 60 M?)

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• LOFAR in Germany
• GLOW German LOng Wavelength consortium
• 6 (7) stations at Bonn (MPIfR), Bremen (IUB),
  Garching, Hamburg, Jülich, Potsdam, (Göttingen)
  2006 - 2009
• plus another 6 2009 2012
• White Paper, to be presented to the Ministry of
  Science

• White Paper presented to
• RDS during fall meeting of the AG
• to ASTRON October 4, 2005

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Science - re-ionization 5 lt z lt 20 ? step
at 70 240 MHz expected - high-z universe -
relic synchrotron sources (census of past AGN
activity) - bursting and transient universe,
GRBs - 327 MHz deuterium line -
solar-terrestrial relationships - CRs
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re-ionization onset of star and galaxy
formation end of "Dark Ages between z 6 and
20 first indications now
Gunn-Peterson trough
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Cosmic rays LOPES _at_ Forschungszentrum Karlsruhe
(H. Falcke)
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• Interdisciplinarity
• astronomy
• precision agriculture
• geophysics
• meteorology (weather prediciton)
• wind energy (wind-flow models)
• water management (Rhine-delta complex)
• electricity transport
• traffic flow
• passive radar (get airplanes down more quckly)