ARTEMIS

Aris Karastergiou

Transcript

1. The  Sun
   Pulsars
   Radio  
   Transients
   Interstellar  
   Medium
   Nanosecond  
   Astronomy
   Ionosphere
   Cosmic  Rays
   The  Unknown
   LOFAR  staAon
   Beamformed
   Data
   

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2. What is ARTEMIS?
   A software/hardware backend to process streaming data, used for
   single-station science at LOFAR-UK, Nancay, Bonn + Onsala.
   Software: AMPP, the artemis modular pelican pipelines
   AMPP: prototype for streaming processing for the SKA and its
   pathfinders. 35 TB/day today. Tomorrow?
   Software: Pelican, a light and scalable framework for distributed
   streaming processing.
   Hardware: AMPP and Pelican have native CPU and GPU support
   AMPP is not a UDP packet recorder
   AMPP is not limited to LOFAR
   AMPP is documented and open to developers
   H5 data product that conforms to LOFAR standard
   

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3. Can be used
   for 100%
   of the time
   

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5. LOFAR international stations
   • Large collecting area (96 coherently added dipoles), high
   sensitivity. 9 international stations = superterp
   • Very fast sampling rate (5 ns), reduced to 5.12 µs for the
   station beams.
   • Large fields of view, 10 to 100s of square degrees.
   • Not used for all LOFAR KSPs.
   

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6. Dispersion searches
   DM 0
   N2 or N logN process per time sample
   (N > 1000 -- 10000+ samples/sec
   HPC computing
   

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7. 6 MHz bandwidth
   HBA UK (ARTEMIS)
   48 MHz bandwidth
   LBA superterp
   

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8. Dell Poweredge C6100
   Dell Poweredge C410x
   Stef
   Salvini
   Wes Armour
   Dalal
   Ait Allal
   Mike Giles
   Chris Williams Steve Roberts
   Fred
   Dulwich
   Ben Mort
   Alessio
   Magro
   Aris
   Karastergiou
   hardware
   

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9. Frequency (MHz)
   Time (ms)
   8000 8200 8400 8600 8800 9000
   143
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   20
   30
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   200 400 600 800
   0
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   6000
   8000
   Time bin
   40 60
   100
   200
   300
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   500
   600
   700
   800
   900
   dB
   Frequency channels
   Pulse
   

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10. Frequency (MHz)
    Time (ms)
    8000 8200 8400 8600 8800 9000
    143
    144
    145
    146
    147
    148
    149
    16
    18
    20
    22
    24
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    28
    30
    200 400 600 800
    0
    200
    400
    Time bin
    22 24 26
    100
    200
    300
    400
    500
    600
    700
    800
    900
    dB
    Frequency channels
    

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11. frequency
    intensity
    frequency
    intensity
    intensity
    frequency
    1. Model the bandpass
    2. Match model to data
    3. Subtract model and filter
    4. Store spectrum
    stats in ring buffer
    5. Update model with
    running averages
    

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12. dynamic noise
    modelling
    for effective RFI
    removal and
    transient detection
    DM
    time (s)
    GPU dedispersion: 4000 dispersion measures searched,
    only pulses from B0329+54 detected, no spurious signals
    filterbank noise
    pre-filtering
    filterbank noise
    post-filtering
    

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13. Dispersion  measure  pc/cm3
    Time  (s)
    Crab
    HAM
    SAT
    HAM
    SAT
    • Working  prototype  for  non-­‐image  processing
    • Real-­‐Bme  searches  for  Individual  Radio  Pulses  using  CPU/GPU
    • Dedispersion  over    4000  DMs  per  beam  in  real  Bme  with  GPUs
    • Pilot  survey  1:  6-­‐8  beams  tracking  circumpolar  targets
    • Pilot  survey  2:  6  beams  fixed  on  the  meridian  from  8o  to  28o  dec
    Pipeline  diagnosBc  plot  from  Pilot  survey  –  daily  summary  from  one  of  six  beams
    Receive  udp  
    stream
    Polyphase  filter
    Raw  to  
    Stokes
    RFI  removal Dedispersion output
    S/N DM
    Time  (s)
    Aris  Karastergiou  (aris@astro.ox.ac.uk)
    Crab
    

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14. • Real time detection system which would easily detect
    RRATs and Lorimer burst as they happened.
    • Affordable and scalable hardware
    • Fastest ever dedispersion code on NVIDIA GPU
    • RFI rejection performing well in very contaminated
    environment
    Crab
    B1919+21
    26 December 2011
    drift scan with beam at Dec=+21º
    B1919+21
    Crab
    time (s)
    ??
    ? ?
    

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15. http://www.oerc.ox.ac.uk/
    research/artemis
    

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16. Buffer of Stokes data
    

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17. Unknown
    sources at DM
    0.9, observed
    simultaneously
    at Chilbolton
    and Nancay
    

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18. Buffer of beamformed voltage data
    PSR B1919+21
    Onsala+Chilbolton
    

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19. Buffer of beamformed voltage data
    PSR B1919+21
    Onsala+Chilbolton
    Interferometric fringes!
    

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20. The hundred
    tied-array-beams
    realtime processor
    LOFAR APERTIF MeerKAT
    SKA-I SKA-II
    RFI-excision dedispersion folding detection
    CPU - GPU cluster
    

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21. 
    
    

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