Westerbork Synthesis Radio Telescope WSRT

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Westerbork Synthesis Radio Telescope (WSRT)
14 telescopes of 25 m - 3 km baseline
Observing wavelengths 3, 6, 13, 18-22, 22-92, 92
cm
Major upgrade just completed Competitive at
international level!!
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Completely upgraded system

• All hardware replaced
• New reduction, analysis visualisation software

• enormous increase in data volumes
• up to 25 Gbyte per single observation

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WSRT data flow
export to user
quality control data inspection (raw data)
calibration reduction
analysis science
observation
visualisation needed
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WSRT data flow
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3-D visualisation of visibility data
New backend produces large amounts of data Need
efficient inspection tools for quality control of
raw data
WSRT is interferometer data is collected per
baseline 14?13/291 baselines (gt)1024 channels,
up to 8 bands 2 (or 4) polarizations 720 time
samples
3D dataset no physical interpretation
raw data visibilities (Fourier Transform of sky)
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Visualisation of visibility data
Traditionally inspection of line plots and
images 9172084 plots No overview of data!!!
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Visualisation of visibility data
Traditionally inspection of line plots and
images 9184 plots (of averaged data) No
overview of data!!!
Average amplitude vs. time for each baseline per
polarisation
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Visualisation of visibility data
Image of amplitude per channel vs. time for a
single baseline and polarisation
Frequency
Time
Would have to look at 9148 of these!!!!
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3-D visualisation of visibility data
Time
Baseline
Frequency
Need possibility for user feedback 3-D
cursor probing
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WSRT data flow
visualisation of science data
export to user
quality control data inspection (raw data)
calibration reduction
analysis science
observation
visualisation needed
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Spectral line datacubes

• Spectral line radio observations give, after
  calibration, 3-D data sets
• after FT datacubes
• sequence of mono-chromatic images
• is physical concept phasespace
• (data actually 4D)

Declination
Frequency (velocity)
Right Ascension
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Neutral Hydrogen? (aka H I)

• Sharp emission line

1420.40575180 MHz
proton electron
proton electron
Doppler effect ? kinematics of celestial
objects!
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Doppler effect
V 0
V lt 0
V gt 0
Frequency ?
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Why Radio Astronomy?
Detect other constituents, e.g. hydrogen or
ionised plasma (magnetic fields)
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The Universe is very different in H I !!!!
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Visualisation of noisy data
Complication noise creates fog and blocks view
of faint data ? need filtering
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Visualisation of noisy data
Complication noise creates fog and blocks view
of faint data ? need filtering
(used
adaptive wavelet filtering)
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optical
unfiltered
filtered
H I
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optical
H I
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Integration in AstroMD
- FitsReader
- ImageClipper
- ImageSlice
- ImageCube
- ProbeLine
- VolumeRender
- LinePlot
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Object Model
AstroMD