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F. Breitling, G. Mann, C. Vocks 3 nd Workshop of the Solar Key Science Project of LOFAR Astrophysikalisches Institut Potsdam 2010 July 05. Solar Data Analysis. Overview The three LOFAR data types. Dynamic spectra Single station imaging Standard imaging RCU: Receiver unit - PowerPoint PPT Presentation
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Solar Data Analysis
F. Breitling, G. Mann, C. Vocks
3nd Workshop
of the
Solar Key Science Project of LOFAR
Astrophysikalisches Institut Potsdam
2010 July 05
2010 July 5 Solar Data Analysis F. Breitling
OverviewThe three LOFAR data types
1. Dynamic spectra
2. Single station imaging
3. Standard imaging
RCU: Receiver unit
RSP: Remote station processing board
TBB: Transient buffer boards
2010 July 5 Solar Data Analysis F. Breitling
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Dynamic spectraData
• Beam-formed data (currently)– Container format: Hirachical Data Format 5 (HDF5)
– Specification: Interface Control Document 3
lofar-usg-icd-003.pdf
• Dynamic spectrum data (maybe in future)– Container format: Hirachical Data Format 5 (HDF5)
– Specification: Interface Control Document 6
lofar-usg-icd-006.pdf
=> both formats are currently under heavy development
Ref: http://usg.lofar.org/wiki/doku.php?id=documents:lofar_data_products
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Dynamic spectraSoftware
• Dynspec package
• developed by Solar KSP (Frank Breitling)
• part of LOFAR User Software (http://usg.lofar.org)
• build on Data Access Layer (DAL)
• Python scripts
• Components – specview.py (can read Fit and HDF5 files)
– downsample.py (can also create Fit files)
– rebin.py
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Dynamic spectraFirst solar observations
Date: 2009-09-11 10:08:52 (ID108)
2009-09-11 13:09:39 (ID109)
Duration: 1h
LOFAR stations: CS302-LBA
RS307-HBA
RS503-HBA
Measured param.: voltages of both polarizations
Subbands/station: 62
Down sampling: 128
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Dynamic spectraFirst results
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Dynamic spectraIdentified problems
– stripe of high intensity in CS302, shifting from subband 30-40 for obs108 to subband 50-60 for obs109
– intensity peaks and drops for subband 0-20 in obs109_CS302LBA
– intensity gradient in obs109_RS503HBA
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Dynamic spectraNext steps
• New versions of the beam-formed and dynamic spectra data format has to be finalized
• Dynspec software can be adapted
• Discussion with Michael Wise and Lars Bähren about their further development plans
• Travel to ASTRON is already planed for July 12-16
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Single station imagingData
• Visibilities from LCU correlator– 96 receiver units (RCUs) x 2 polarizations x 16 byte
– Format: Binary
– Specification: • Menno Norden <norden at astron.nl>• rspctl --help (running on LCU)
Reference: http://usg.lofar.org/forum/index.php?topic=202.0
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Single station imagingSoftware
• acm2skyimage.m
• developed by Stefan Wijnholds <wijnholds at astron.nl>
• runs with Matlab and Octave
• Extended components by Frank Breitling– SolarAzEl.m to add the Sun
– RADec2AzEl.m to add other astronomical objects
(also published as Matlab package at http://www.mathworks.com/matlabcentral/fileexchange/25617-right-ascensiondeclination-to-azimuthelevation)
– make-movies.sh
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Single station imagingPotsdam commissioning
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Single station imagingResults from Effelsberg
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Single station datacombining with GURT
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Standard imagingBasics
• Basic data analysis software– CASA (Common Astronomy Software Applications)
http://casa.nrao.edu/
• Data format– Measurements Sets (MS) from CASA
• Data processing: Standard Imaging Pipeline– The LOFAR wiki
http://www.lofar.org/wiki/doku.php?id=software:standard_imaging_pipeline
– The LOFAR Imaging Cookbookhttp://www.mpa-garching.mpg.de/~fdg/LOFAR_cookbook/LOFAR_Cookbook_v2.3.pdf
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Standard imagingPipeline
Components
• OLAP: Online Application Processing (Blue Gene/P correlator)
• DP3/DPPP: Default Pre-Processing Pipeline (for flagging and averaging)
• BBS: BlackBoard Selfcal (calibration)
• CImager: Imager
Control
• via parset files
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Standard imagingFirst solar observations
Date: 2010-06-09 10:17:00, 11:41:00, 13:40:00, 15:40:00
Duration: 4 x 10 Min
LOFAR stations: 20 CS +3 RS, i.e.
RS106HBA, RS306HBA, RS503HBA
[CS00{1-7}, CS0{21,30}, CS103] HBA{0,1}
Measured param.: complex visibilities, 2 polarizations
Frequency range: ~150-220 MHz
Subbands /station: 7
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Standard imagingData Inspection with casaplotms
• a lot of RFI• flagging with
flagdata• creation of
NDPPP.parset reprocessing
with NDPPP
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Standard imagingSky model
Calibration using BlackBoard Selfcal requires skymodel
File contents of 078xx.skymodel:
# (Name, Type, Ra, Dec, I, Q, U, V, ReferenceFrequency='60e6',
SpectralIndexDegree='0', SpectralIndex:0='0.0', MajorAxis, MinorAxis, Orientation) = format
# The above line defines the field order and is required.
TauA.neb, GAUSSIAN, 05:34:32.00, +22.00.52.00, 1888.55, 0.0, 0.0, 0.0,81.5e6, 0, -0.299, 420.0, 290.0, 0.0
3C123, POINT, 04:37:04.72, +29.40.15.6, 454.97
3C133, POINT, 05:02:58.58, +25.16.22.7, 44.67
3C131, POINT, 04:53:23.26, +31.29.26.4, 37.54
3C139.2, POINT, 05:24:26.92, +28.12.54.2, 35.88
3C141, POINT, 05:26:43.55, +32.50.02.0, 31.76
3C132, POINT, 04:56:43.00, +22.49.23.7, 24.39
4C29.17, POINT, 05:10:40.10, +29.09.00.5, 19.48
4C29.16, POINT, 05:09:29.50, +29.57.56.3, 17.43
3C138, POINT, 05:21:10.46, +16.38.26.0, 14.63
PKS0531, POINT, 05:34:44.65, +19.27.21.9, 14.52
Taken from “The VLA Low-Frequency Sky Survey” catalog (http://www.cv.nrao.edu/4mass/VLSSlist.shtml)
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Standard imagingBBS calibration
After running the BBS calibration
amplitudes and phases are stable
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Standard imagingmwimager
after calibration the master worker imager creates:
– PSF – dirty image– clean image
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Standard imagingDirty image
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Dirty image
not yet sucessful
Standard imagingNext steps
• investigation of 2s clock offset of CS002-CS007
(found by Olaf Wucknitz)
• BBS calibration without short baselines
(suggested by James Anderson)
• automatic flagging of RFI
• travel to ASTRON on July 12-16 and discuss with the experts Ger van Diepen and Ger de Bruyn
• take more observations, e.g. new data on July 03
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Progress documentation
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Solar Science Data CenterYearly data volume
for solar observations with LOFAR
(assuming a maximum observation time of 8h/d)
Observation timegranted to the SKSP
Data per year[TB/yr]
Data rate[MB/s]
33% (maximum) 104 100
5% 16 100
3% 9.5 100
Summary
• The SKSP is engaged in 3 types of data analysis
• Dynamic spectra can already be taken, next the new format has to be completed
• Single station imaging is important for commissioning, single station operations and for our colleagues from GURT
• Standard imaging is the newest data for the SKSP and will need a lot of attention in the future
• Ultimately we plan for a Solar Science Data Center and work is ongoing
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References
• User Software Group: http://usg.lofar.org/• LOFAR User Forum: http://usg.lofar.org/forum/index.php• LOFAR Interface Control Documents (ICDs)
http://usg.lofar.org/wiki/doku.php?id=documents:lofar_data_products• Documentation for the Standard Imaging Pipeline
http://www.lofar.org/wiki/doku.php?id=software:standard_imaging_pipeline• The LOFAR Imaging Cookbook
http://www.mpa-garching.mpg.de/~fdg/LOFAR_cookbook/LOFAR_Cookbook_v2.3.pdf
• Frank Breitling <fbreitling at aip.de> http://www.aip.de/People/fbreitling/
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Yearly observation time
at Exloo (core stations) altitude >10° above horizon
=> tobs=~8 h/d =10x106 s/y
(Maximum possible)
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