MAURITIUS CALLISTO SPECTROGRAPH
The radio emission of solar flares comes in many varieties, probably reflecting different emission processes and physical origins. The emissions are distinct in their spectrum and temporal behavior. The radiations are caused coherently by electron beams, shocks, possibly trapped electrons, and high-frequency waves in the plasma. The incoherent gyro synchrotron radiation is the only really broadband radio emission. As the radio emissions carry information on shocks, energetic electrons and their acceleration, but are still largely unknown, research in flare radio emissions will grow in the near future. In view of space weather implications, meter wave bursts have seen a renewed interest, particularly in combination with observations at other wavelengths. Spectrometers are necessary to identify the nature of coherent solar flare radio emission. Interferometers do not have sufficient frequency channels to replace spectrometers with high frequency resolution, as some decimeter bursts have bandwidths of less than one percent of the center frequency.
Here we describe the new radio spectrometer CALLISTO. (Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories). Its main focus is solar flare radio observation.
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A Callisto spectrometer was recently set into operation at MRT station of the UoM (University of Mauritius). This, to study metric and decimetric radio events of the active sun.
Figure1:-Basic design of the radio spectrometer CALLISTO for solar flare observations.
Figure 2. The hardware of CALLISTO shown in the foreground consists of the
main board for data acquisition and interface with a RISC processor ATmega16
(left) and of two synchronous receivers (right). The complete spectrometer is shown
in the background. Its physical size (width) is 24 cm.
Figure2:-Spectral overview at MRT location taken with self built broad-band log-per antenna. The signal is amplified by a low noise amplifier with about 20 dB of gain and < 2 dB noise figure. Plot shows 13’120 channels between 45MHz and 870 MHz with a separation of 62.5 KHz. Integration time is roughly 1 msec in full sensitivity of Callisto. This location is perfect for meter and decameter wave observation.
CALLISTO NET WORK AND THE PEOPLE
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Christian Monstein
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ETHZ
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Arnold O. Benz
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ETHZ, Switzerland
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P. K. Manoharan
D. Nandagopal
R. Venkatasubramani
A. J. Selvanayagam
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NCRA Ooty, India
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R. Ramesh
V. C. Kathiravan
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IIA Gauribidanur,
Bangalore, India
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Alexander Altyntsev
Sergey Lesovoi
Andrey Maslov
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SSRT Badary/Irkutsk
Russian Federation
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Jorge Paez
Marco Barantes
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CINESPA, Costa Rica
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Alejandro Lara
Gaudencio Paz Martinez
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UNAM, Mexico
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Kyungsuk Cho
SuChang Bong
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KASI, Daejeon,
South Korea
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Frédéric Clette
Christophe Marqué
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ROB, Bruxelles
Belgium
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Hanumant Sawant
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INPE Brazil
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Ericson Lopez
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Ecuador
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Girish Kumar Beeharry
Rajasekhara Gauribidanur
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MRT Bras d'Eau, Poste de Flacq, Mauritius
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Usnikh Sukhbaatar
S. Demberel
D. Batmunkh
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RCAG in Khurel Togoot near Ulaanbaatar, Mongolia
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Andreas James
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ETHZ
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Peter Messmer
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TXCORP, USA
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P. Gallagher
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Dublin, Ireland
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N. Gopalswamy
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NASA/GSFC, USA
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David Webb
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Editor IHY newsletter
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B. Thompson
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NASA/GSFC, USA
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H. Haubold
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UN Office, Vienna
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General information about Callisto:
http://www.astro.phys.ethz.ch/instrument/callisto/callisto_nf.html
Software and related products about Callisto:
http://www.astro.phys.ethz.ch/instrument/callisto/ecallisto/applidocs.htm
Access to data achive and DiRaC:
http://www.astro.phys.ethz.ch/rapp/rapp_home_nf.html
Reference and with acknowledgements to:-
CALLISTO - A New Concept for Solar Radio
Spectrometers
Arnold O. Benz, Christian Monstein and Hansueli Meyer
Institute of Astronomy, ETH Z¨urich, CH-8092 Zurich, Switzerland
