Analysis and Simulations of 6T MWA Solar Data · Pauli Kehayias August 7, 2008 1 Analysis and Simulations of 6T MWA Solar Data ... REU Final Presentation. Pauli Kehayias August 7,
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Pauli Kehayias August 7, 2008 1
Analysis and Simulations of 6T MWA Solar Data
Pauli Kehayias Tufts University
REU Final Presentation
Pauli Kehayias August 7, 2008 2
MWA Background 1
- Murchison Widefield Array- 512 tile array
- 16 dipoles per 5 × 5 m tile
- Tiles spread over 1.5 km radius- 80 – 300 MHz range- 15° – 50° field of view (zenith)
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MWA Background 2
[1]
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MWA Background 3
[2]
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MWA 6T Prototype Array
[3]
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6T Solar Data
- Two hours of solar data collected (April 28, 2008)- 85 MHz, 180 MHz- 0.1 s time resolution- 10 kHz / channel, 128 channels- Alternating 2 minute runs
- Analysis motivations- Solar transients- Radio frequency interference (RFI)- Instrument performance
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Bandshapes 1
Visibilities(data)
Time
Average over time
Bandshape
128
chan
nels
Time series
Freq
uenc
y
Freq
uenc
y
Time
Average over frequency
Tiles
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Bandshapes 2
Good Bad
- 10 s average bandshape- 4/12 input signals were found to be faulty
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Transients 1
- Transient search algorithm:- Calculate 2 hr average bandshapes- Compare to 10 s average bandshapes- Look for large deviations
- Findings- Four event types- All thought to be RFI or instrumental – no solar transients
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Transients 2
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Bandshape Stability
- Examine bandshape noise over time to study performance
- Compare 10 s bandshapes to an average:- “Global” bandshape: over all data- “Local” bandshape: over the current run (2 min)
- Get root mean square (RMS) difference
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Local RMS (85 MHz)
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Average Bandshape Scaling (85 MHz)
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Average Bandshape Scaling (180 MHz)
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Bandshape Scaling Simulations
- Bandshape scaling can be due to varying signal from the sky
- Simulate potential sources:- Background radio sky- Sun (changing orientation and antenna gain)
- Results- Background radio sky is not the sole cause- Sun simulation underway
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Background Radio Sky SimulationBaseline 3, 8
85 MHz
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Sun Simulation 1
- Solar disk: 32’ [4]- 6T resolution:
- 85 MHz: ~40’ – 190’- 180 MHz: ~20’ – 90’- Vary over time
- Sun radio emission brighter near disk edge
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Sun Simulation 2Si
mul
atio
nD
ata
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Acknowledgements
Divya Oberoi
Roger CappalloRich CrowleyPhil Erickson
Madeleine NeedlesK.T. Paul
Preethi PratapAlan Rogers
Randall Wayth (CfA)
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References
1. http://maps.google.com “-26.7033194, 116.6708139”.2. MWA TWiki, Expedition 1 photos,
http://mwa-lfd.haystack.mit.edu/twiki/pub/Main/TilePhotos/tile016w.jpg.3. MWA TWiki, X3.1 Results and Analysis, Divya’s map of selected tiles for X3.1,
http://mwa-lfd.haystack.mit.edu/twiki/pub/Main/ResultsAndAnalysis/do_8T_selection.pdf.4. NASA National Space Science Data Center Sun Fact Sheet.
http://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html.5. S. F. Smerd (1950), Australian J. Sci. Res. A 3, 34.
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MWA Science Goals
- Epoch of Reionization – 21 cm H emission, z = 6.5- Radio sky survey / transient search- Space weather (solar bursts, Faraday rotation, IPS)
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Average Bandshapes (85 MHz)
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Average Bandshapes (180 MHz)
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Transients 3
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Global RMS (85 MHz)
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Sun Simulation 3
[5]
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