Figure 2. Trieste CALLISTO Station setup at Basovizza
The Trieste CALLISTO station (http://radiosun.oats.inaf.it) was established in 2012 at the Basovizza Observing Station (45 ° 38 37″ N, 13 ° 52 34 E”, 398m above MSL) run by the Italian National Institute for Astrophysics (INAF)– Astronomical Observatory of Trieste (Italy) to study solar radio bursts and the action of the Earths ionosphere and geomagnetic field..
3 CALLISTO spectrographs are presently set up at Trieste CALLISTO Station (see Figure 2), tasting the radio spectrum in the 45-80 MHz, 220-420 MHz and 905-1730 MHz bands with in overall 600 frequency channels and a temporal resolution of 250 ms per sweep.
This configuration of CALLISTO receivers and making use of a 2-elements Yagi VHF I band antenna, a broadband 130-1000 MHz LPDA and a cross LPDA antenna using a frequency down-converter, developed and constructed by one of the authors, enables a good tasting of the spectra with a low-cost system. Given that June 2012, a variety of Type I, II, III, IV and V radio bursts have actually been identified (see example in Figure3), in spite of the site RFI level.
Figure 3. Type III (left) and type II burst (centre) with GOES X-ray flux data overlaid on the spectrogram.
A specific website (http://radiosun.oats.inaf.it) has actually been set up to gain access to Trieste CALLISTO Station local information (quicklooks/FIT files) by date together with National Oceanic and Atmospheric Administration NOAA solar occasions daily report and GOES X-RAY flux plot.
An experimental automated radio burst detection system is active too. Its results are shown clicking the three buttons corresponding to the 3 different monitored frequency bands (see example screenshot in Figure 4): there are offered links to the FIT files of the spectrograms consisting of bursts, quicklooks and the bursts appearance times.
Figure 4. Results of automated radio burst detection.
Conclusions.
Three CALLISTO spectrographs are presently installed at Trieste CALLISTO Station, tasting the radio spectrum in the 45-80 MHz, 220-420 MHz and 905-1730 MHz bands with in overall 600 frequency channels and a temporal resolution of 250 ms per sweep.
Because June 2012, a number of Type I, II, III, IV and V radio bursts have actually been detected, regardless of the website RFI level. As an example, from 1st November 2020 to 14th October 2021 Trieste CALLISTO station tape-recorded 122 bursts.
Some efforts to immediately detect solar radio bursts have been performed and a basic detection algorithm used to Trieste CALLISTO station only is currently active and produces results affected by a number of false positives due to RFI. Other detection algorithms are presently being studied used both to regional data only and to numerous CALLISTO stations in order to get rid of RFI and noise. A deep-learning detection algorithm is under advancement to spot lightning strikes recorded in the spectrograms, making money from the a great deal of strikes in this area which could be utilized in the training and test sets.
As soon as possible L-band observations will be performed using a 3 meter dish, now under upkeep. This reality will improve the sensitivity and the S/N ratio, thinking about the narrow beam width of the meal tracking the Sun.
Based upon a recent paper: A. Marassi and C. Monstein, 2022, Trieste CALLISTO station setup and observations of solar radio bursts, Advances in Space Research, 69, Pages 2589-2600 DOI: 10.1016/ j.asr.2021.12.043.
Referrals.
Benz, A.O., Monstein, C., Meyer, H., 2005. Callisto A New Concept for Solar Radio Spectrometers. Sol. Phys. 226, pp. 143– 151.
Benz, A.O., Monstein, C., Meyer, H., et al, 2009. A World-Wide Net of Solar Radio Spectrometers: e-CALLISTO. Earth Moon Planets 104, pp. 277– 285..
McLean J., Labrum N.R., 1985. Solar Radiophysics, Studies of Emission from the Sun at Metre Wavelengths. Cambridge University Press, New York.
Zucca, P., Carley, E.P., McCauley, J., et al, 2012. Observations of Low Frequency Solar Radio Bursts from the Rosse Solar-Terrestrial Observatory. Sol. Phys. 280( 2 ), pp. 591– 602.
* Alessandro Marassia, Christian Monsteinb.
aINAF– Astronomical Observatory of Trieste, through GiamBattista Tiepolo, 11 34143 Trieste (Italy), bIstituto Ricerche Solari (IRSOL), Università della Svizzera italiana (USI) CH-6605 Locarno-Monti (Switzerland).
A solar radio burst (SRB) is the extreme solar radio emission often related to a solar flare and one of the potentially severe area weather condition events which might affect Earths ionosphere and signal propagation, cordless communication, power grids and navigation systems. If an SRB takes place with the enhancement in L band radio flux, it could influence the Global Navigation Satellite Systems (GNSS) signals through direct radio wave interferences. The significant space weather events like solar flares and coronal mass ejections are usually accompanied by solar radio bursts, which can be used for a genuine time space weather condition projection (White, 2007).
Some efforts to instantly find solar radio bursts have been performed and an easy detection algorithm applied to Trieste CALLISTO station only is presently active and produces outcomes impacted by a number of incorrect positives due to RFI. Callisto A New Concept for Solar Radio Spectrometers.
Figure 1. Real-time map of existing distribution of Callisto instruments 10 March 2021 16:05:04 UTC. One dot can represent as much as 5 instruments.
In this paper we explain the Trieste CALLISTO station, the local e-Callisto network digital archive, Trieste CALLISTO Radio Bursts Detection and Visualization System readily available via web.
A solar radio burst (SRB) is the extreme solar radio emission frequently related to a solar flare and among the possibly severe area weather condition events which might affect Earths ionosphere and signal propagation, wireless interaction, power grids and navigation systems. It might influence the Global Navigation Satellite Systems (GNSS) signals through direct radio wave interferences if an SRB happens with the enhancement in L band radio flux. The major space weather events like solar flares and coronal mass ejections are generally accompanied by solar radio bursts, which can be utilized for an actual time space weather forecast (White, 2007).
They are classified into 5 primary types (McLean and Labrum 1985 and others), mainly based on how they appear in dynamic spectrum observations from radio spectrographs.
Several radio instruments have been created to monitor solar radio activity, consisting of imaging-spectrometers, interferometers and spectrometers (Zucca et al. 2012).
The CALLISTO spectrometer is a programmable heterodyne receiver developed at ETH Zurich, Switzerland (Benz et al. 2005) during 2006 in the framework of International Heliophysical Year (IHY2007) and International Space Weather Initiative (ISWI). CALLISTO is an acronym standing for Compound Astronomical Low frequency Low expense Instrument for Spectroscopy and Transportable Observatory.
A number of CALLISTO spectrometers are released around the world and together form the e-Callisto network (Benz et al. 2009). A map of present circulation of e-Callisto instruments 10 March 2021 is revealed in Figure 1.
