CALLISTO is the Compound Astronomical Low frequency Low cost Instrument for Spectroscopy and Transportable Observatory. It is part of an international network of similar instruments around the globe, dedicated to the 24hr monitoring of solar radio bursts. The system is designed to measure the dynamic spectra of Type II and Type III radio bursts produced by coronal shock waves and by near-relativistic electrons streaming along open magnetic field lines, as well as Type I, IV and V bursts due to other solar energetic processes.
RSTO employs three CALLISTO receivers. The low receiver operates at 10 - 100 MHz and is fed by a bicone antenna. The mid and high receivers operate at 100 - 200 MHz and 200 - 400 MHz, respectively, and are fed by a log-periodic antenna. At nominal operation each receiver takes four spectra per second, with 200 channels in its respective band. Each of the instruments observe automatically and their data is collected each day and stored here at RSTO and also in a central data-base at ETH Zurich.
LOFAR test array
RSTO employs other two CALLISTO receivers connected to an array of four LOFAR low frequency band (LBA) antennae. This setup aims to test the response of the LBA recording dynamic spectra from 10 to 90 MHz in both left and right circular polarizations.
Ionospheric Disturbances at Very Low Frequencies
The SID Monitor (Solar Sudden Ionospheric Disturbance Monitor) built by Stanford University is a space weather instrument to monitor the effects of solar flares on Earth by tracking the changes in very low frequency (VLF) transmissions. The SID monitor is tuned to a frequency of 24.0 kHz and therefore it is sensitive to VLF transmissions from Cutler, Maine, USA (Station ID: NAA). Sudden Ionospheric Disturbances (SIDs) occur in association with solar flares and have a very strong and relatively long-lasting effect on the ionosphere (Thomson and Cliverd, 2001). Earth’s dayside ionosphere responds quickly and dramatically to the X-ray and EUV input by an abrupt increase in total electron content. This can cause disruptions in telecommunications and also have an effect on the GPS network. It is also of interest to military institutions since VLF transmissions are operated by navies for long-range communications with submarines. In fact, monitoring of such long-range communications allows us to detect solar-induced ionospheric disturbances by measuring changes in the amplitude and phase of waves from military transmitters.
In March 2016, collaborators from the Russian Academy of Science Schmidt Institute of Physics of the Earth installed an an Ultra MSK VLF receiver at the Rosse Observatory. This enables us to simultaneously monitor 14 VLF stations from across the world at ~1 Hz.
The LEMI magnetometer measures the flux of the local magnetic field in three components Bx, By, and Bz. The instrumentation comprises eight electrodes to measure the Earth's electric field, connected by buried coaxial cable, towards a centred datalogger and a fluxgate magnetometer, to measure the Earth's magnetic field. The low noise, high resolution magnetotelluric instrumentation is shown on the right. Fluxgate on the left foreground, data logger in the centre and electrodes on the right background.
DIAS Seismic Array Station
Ireland Array is a seismic experiment conducted by the Dublin Institute for Advanced Studies (DIAS) Geophysics. Ireland Array is a seismic antenna the size of Ireland, aimed deep down into the Earth. It records slightest vibrations of the Earth's surface caused by distant earthquakes. The new data will reveal the structure of the Earth's crust and deeper lithosphere of the tectonic plate under the entire island. Ireland Array operates 30 portable seismic stations. A part of the array (its backbone component) consists of 20 stations, distributed uniformly across Ireland, equipped with very-broad-band Trillium 120PA seismometers, and deployed for 5 years. The second, mobile component consists of 10 Guralp T40 broad-band sensors, deployed so as to zoom in on local structure in finer detail. The new seismic observations will produce unprecedentedly detailed images of Ireland's subsurface.
Left: low frequency bicone (10 - 80 MHz) antennae.
Right: CALLISTO high frequency log-periodic (55 - 400 MHz).
LOFAR test LBA antennae (10 - 90 MHz).
SID magnetic loop antenna operating at 24.0 kHz. It detects VLF signals
from Cutler, Maine, USA.
The international network of VLF stations monitored by the
Ultra MSK VLF receiver at Birr, Ireland,
Three-axis fluxgate magnetograph (left), data logger (centre) and E-field electrodes (top right).