SKA: Configurations and Simulations Ramesh Bhat Colin Lonsdale Roger Cappallo Shep Doeleman Divya...
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Transcript of SKA: Configurations and Simulations Ramesh Bhat Colin Lonsdale Roger Cappallo Shep Doeleman Divya...
![Page 1: SKA: Configurations and Simulations Ramesh Bhat Colin Lonsdale Roger Cappallo Shep Doeleman Divya Oberoi Joanne Attridge MIT Haystack Observatory.](https://reader035.fdocuments.in/reader035/viewer/2022070605/5a4d1aef7f8b9ab05997d4d6/html5/thumbnails/1.jpg)
SKA: Configurations and Simulations
Ramesh BhatColin LonsdaleRoger CappalloShep DoelemanDivya Oberoi
Joanne Attridge
MIT Haystack Observatory
![Page 2: SKA: Configurations and Simulations Ramesh Bhat Colin Lonsdale Roger Cappallo Shep Doeleman Divya Oberoi Joanne Attridge MIT Haystack Observatory.](https://reader035.fdocuments.in/reader035/viewer/2022070605/5a4d1aef7f8b9ab05997d4d6/html5/thumbnails/2.jpg)
Simulator Functions• A general purpose tool for LOFAR/SKA studies • Create Synthetic Data Sets
– Performance simulations, at high level design specs– Realistic effects: Ionosphere, Variable beams, Skies
• Configuration Studies– Explore Design Parameter Space:
• Automation to allow efficient searches• Identify trends in performance
• Testing Calibration and Postprocessing• Direct access to structures solved for• Controlled environment for isolation of effects• Test New Postprocessing Algorithms
• Science Applications (e.g. EOR)
![Page 3: SKA: Configurations and Simulations Ramesh Bhat Colin Lonsdale Roger Cappallo Shep Doeleman Divya Oberoi Joanne Attridge MIT Haystack Observatory.](https://reader035.fdocuments.in/reader035/viewer/2022070605/5a4d1aef7f8b9ab05997d4d6/html5/thumbnails/3.jpg)
Simulator Status• Includes
– FITS Image import– Variable station beams– Thermal Noise (Rx)– Arbitrary array configuration.– Arbitrary station config.– Gaussian sources– Arbitrary time/freq obs.– True parallelization in time.– Functional parallelization
otherwise– Exportable to FITS– Script driven to support
automated parameter searches
– 4-D Ionosphere with line integration.
– Site mask incorporation– Sky noise due to Galactic
Background.
• Will Include– Polarization– Realistic skies– Source Spectral Index– Out-of-beam source
contributions (CasA in sidelobes, etc…)
– Extension to 3-D FFTs for wide field imaging.
– RFI (limited)
![Page 4: SKA: Configurations and Simulations Ramesh Bhat Colin Lonsdale Roger Cappallo Shep Doeleman Divya Oberoi Joanne Attridge MIT Haystack Observatory.](https://reader035.fdocuments.in/reader035/viewer/2022070605/5a4d1aef7f8b9ab05997d4d6/html5/thumbnails/4.jpg)
Functional Flow Diagram
array skies obs_spec sitesproc_spec
configgenerator LOsim
Script driven Simulator Module
(u,v) FITS
MIRIADPSF StatsImagingFidelity
Calibrationstructures forcomparison
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Image Import and SimulationBefore After
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Effect of Variable Station Beams
![Page 7: SKA: Configurations and Simulations Ramesh Bhat Colin Lonsdale Roger Cappallo Shep Doeleman Divya Oberoi Joanne Attridge MIT Haystack Observatory.](https://reader035.fdocuments.in/reader035/viewer/2022070605/5a4d1aef7f8b9ab05997d4d6/html5/thumbnails/7.jpg)
• 20 nodes
– 2.4 GHz P4, $900 each
– 1 Gbyte of RAM
– 60 Gbyte of disk
• Gigabit ethernet switch
– 24-port
– $2000
• UPS and misc
• Excellent price/performance
– 50-80 Gflops
– 1.5 Tbytes of disk
– <$25,000
Simulator Beowulf
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Configuration Studies - in progress
• Parameter space is vast:• Configurations (log spirals, random,…)• Number of stations (variable sensitivity …)• No of elements/station, Staion layout• Bandwidth and integration time• Sky properties and observing geometry• Frequency, polarization, spectrum, …• Weighting schemes, tapering• Ranges of corrupting influences.
• Strategy: parameterize configurations and explore limited ranges, identify trends
• Input from ALMA, ATA, SMA studies.
Proposed USSKA Configuration
Inner ~100 km array
![Page 9: SKA: Configurations and Simulations Ramesh Bhat Colin Lonsdale Roger Cappallo Shep Doeleman Divya Oberoi Joanne Attridge MIT Haystack Observatory.](https://reader035.fdocuments.in/reader035/viewer/2022070605/5a4d1aef7f8b9ab05997d4d6/html5/thumbnails/9.jpg)
Figures of Merit:
• PSF statistics: RMS, size, min, max, deviation. Computed for declination, integration, bw.
• Cable Length (Prim’s Algorithm).• Sensitivity Loss due to: weighting, fixed taper.• PSF statistics for Inner compact array/core.• Image fidelity for a few benchmark images.• Robustness: impact of random station loss.• Calibratability: requires calibration software.
![Page 10: SKA: Configurations and Simulations Ramesh Bhat Colin Lonsdale Roger Cappallo Shep Doeleman Divya Oberoi Joanne Attridge MIT Haystack Observatory.](https://reader035.fdocuments.in/reader035/viewer/2022070605/5a4d1aef7f8b9ab05997d4d6/html5/thumbnails/10.jpg)
Searching in Parameter Space
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Configuration Optimization
Figures of Merit:PSF RMS vs RadiusPSF Beam SizeCable Length
![Page 12: SKA: Configurations and Simulations Ramesh Bhat Colin Lonsdale Roger Cappallo Shep Doeleman Divya Oberoi Joanne Attridge MIT Haystack Observatory.](https://reader035.fdocuments.in/reader035/viewer/2022070605/5a4d1aef7f8b9ab05997d4d6/html5/thumbnails/12.jpg)
Configuration Optimization
Figures of Merit weighted And Combined into Optmization function
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Configuration Editor
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Progress so far and Future Work• Good progress with the simulator package,
downstream pipeline, automation, FOMs.• Many configs tested so far, calculation of FOMs. • Continue extensive configuration studies
– Explore N, Nant/station, station layout, etc. – Range of observing conditions, time/bw effects. – Configuration evaluation along FOM axes
• Continue Code Development– New modules based on priority