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VIRGO - E.G.O. ELF Monitoring
station Live data from CASCINA (PI), Italy, South Europe |
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Maintained
by: Federico Paoletti - INFN Pisa (IZ5EBO),
Irene Fiori - E.G.O., Giulio Ballardin -
E.G.O. and Maria C. Tringali
(E.G.O.). FFT processing by Renato Romero.
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The Virgo detector for gravitational waves consists mainly in a Michelson laser interferometer made of two orthogonal arms being each 3 kilometers long. Multiple reflections between mirrors located at the extremities of each arm extend the effective optical length of each arm up to 900 kilometers. Virgo is located within the site of EGO, European Gravitational Observatory.
Untreated correlated magnetic noise from Schumann resonances across two or more detectors provides a fundamental limit on the sensitivity of stochastic searches. One method of reduction is the use of magnetometers to subtract the correlated noise, where a Wiener filter scheme may be implemented. Effective subtraction requires precise measurement of global electromagnetic fields in areas with low local electromagnetic contamination.
It is performed with Metronix MFS-06 magnetometers, from which the spectrograms of this page are also extracted and processed: the signal of the two magnetometers at VIRGO is transformed into a low sampling rate RAW stream (1000 sample/sec), and sent to Cumiana monitoring station (300 km away). There, a PC receives and processes it with SpectrumLab, in 4 different sessions and representations.
Signal coming from two Metronix MFS-06e induction coils: NS reception on top, EW reception on bottom. The NS channel is temporarily out of service due to a fault.
Scroll time 40 seconds, FFT resolution 15.6 mHz.
Signal coming from EW Metronix MFS-06e induction coil.
Scroll time 40 seconds, FFT resolution 15.6 mHz. Scroll time 4.6 seconds, FFT resolution 122 mHz.
Signal coming from EW Metronix MFS-06e induction coil. Daily strips.
Scroll time 108 seconds, FFT resolution 3.8 mHz. Scroll time 4.6 seconds, FFT resolution 122 mHz.
Signal coming from EW Metronix MFS-06e induction coil. Hourly strips.
Scroll time 4.6 seconds, FFT resolution 122 mHz.
Real time situation about lighting strikes in Europe. Courtesy of http://www.blitzortung.org
