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Solar dynamic spectra C. Vocks and G. Mann 1. Spectrum of the quiet Sun: First results 2. How to obtain spectra: Beamformed data 3. Single station spectra.

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Presentation on theme: "Solar dynamic spectra C. Vocks and G. Mann 1. Spectrum of the quiet Sun: First results 2. How to obtain spectra: Beamformed data 3. Single station spectra."— Presentation transcript:

1 Solar dynamic spectra C. Vocks and G. Mann 1. Spectrum of the quiet Sun: First results 2. How to obtain spectra: Beamformed data 3. Single station spectra 4. Summary and outlook 4 th Solar KSP Workshop, 08.-09. November 2010

2 First solar spectrum: LBA Quiet Sun: 11 September 2009 Thermal emission Rayleigh-Jeans: I  f 2 Broad maximum, not as expected… Reason: No calibration Antenna sensitivities 4 th Solar KSP Workshop, 08.-09. November 2010

3 Antenna sensitivity: LBA

4 4 th Solar KSP Workshop, 08.-09. November 2010 Normalized spectrum Plot: Dashed line: Itensity Solid line: I / f 2 Evidence for thermal emission above 60 MHz Lower f: Noise-dominated (synchroton radiation) Above 60 MHz: Dotted line increases Solid line is flat!

5 4 th Solar KSP Workshop, 08.-09. November 2010 First solar spectrum: HBA Quiet Sun: 11 September 2009 Thermal emission Rayleigh-Jeans: I  f 2 Again broad max., lot of RFI…

6 4 th Solar KSP Workshop, 08.-09. November 2010 Antenna sensitivity: HBA

7 4 th Solar KSP Workshop, 08.-09. November 2010 Normalized spectrum Plot: Dashed line: Itensity Solid line: I / f 2 Clear evidence for thermal emission

8 4 th Solar KSP Workshop, 08.-09. November 2010 Normalized spectrum Plot: Dashed line: Itensity Solid line: I / f 2 Clear evidence for thermal emission

9 4 th Solar KSP Workshop, 08.-09. November 2010 How to get dynamic spectra Necessary: Beamformed data → Station beam points to the source Beamformer: 1 sample per 5 µs On station level: Auto- and cross-correlation spectra  Integration over time  Each subrack sends 64 subbands to IP address  No time integration at station  12.8 Mbit/s per subband

10 4 th Solar KSP Workshop, 08.-09. November 2010 Spectra via Groningen Processed by Blue Gene / P Channels within subbands: Frequency resolution Data written to postprocessing cluster: Raw beamformed Dynamic spectra pipeline:  Desired time and frequency resolution  Data output as HDF5 or FITS Synergies with Pulsar KSP

11 4 th Solar KSP Workshop, 08.-09. November 2010 Recent dynamic spectra Solar observations: 29 and 30 October 2010 Data processing:  Pulsar pipeline Work in progress: Read data (python) Store spectrum, e.g. FITS  Scintillation

12 4 th Solar KSP Workshop, 08.-09. November 2010 Single-station spectra Beamformed data: Data streams from subracks Needs to be stored: local PCs, one per subrack For full bandwidth: 4 PCs Data handling: Previous estimates: Time integration and few channels  Computational load manageable PELIKAN software

13 4 th Solar KSP Workshop, 08.-09. November 2010 Summary and future work Summary: Single LOFAR stations: Used as spectrometer Thermal emission of the quiet Sun detected Dynamic spectra: Beamformed data Future work: Solar observations end of October, analyze data BF pipeline from pulsar group, scintillation Dynamic spectrum data format Station sends high data rate, pipeline in Groningen Local storage: PC receives data, PELIKAN


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