International Network of Solar Radio Spectrometers, a Space Weather Instrument Array
DSES is in the process of installing an e-Callisto station. We have installed an antenna on a short tower that tracks the Sun and a software defined radio module that will capture raw data. We have yet to install the computer and software that will process this data and send it to the international e-Callisto server but that activity is under way.
Goal: Understanding Transient Phenomenon in the Solar Corona
The CALLISTO spectrometer is a programmable heterodyne receiver designed 2006 in the framework of IHY2007 and ISWI by Christian Monstein (PI) as member of the former Radio Astronomy Group (RAG) at ETH Zurich, Switzerland. CALLISTO is an artificial word, composed as ‘Compound Astronomical Low frequency Low cost Instrument for Spectroscopy and Transportable Observatory’. The main applications are observation of solar radio bursts for astronomical science, education, outreach and citizen science as well as rfi-monitoring. The instrument natively operates between 45 and 870 MHz using a modern, commercially available broadband cable-TV tuner CD1316 having a frequency resolution of 62.5 KHz. The data obtained from CALLISTO are FIT-files with up to 400 frequencies per sweep. The data are transferred via a RS-232 cable to a computer and saved locally. Time resolution is 0.25 sec at 200 channels per spectrum (800 spectral pixels per second). The integration time is 1 msec and the radiometric bandwidth is about 300 KHz. The overall dynamic range is larger than 50 dB. For convenient data handling several IDL-, PERL- and Python-routines were written.
Many CALLISTO instruments have already been deployed worldwide through the IHY/UNBSSI and ISWI instrument deployment program, CALLISTO is able to continuously observe the solar radio spectrum for 24h per day through all the year. All CALLISTO spectrometers together form the e-Callisto network. CALLISTO in addition is dedicated to perform radio-monitoring within its frequency range with 13’200 channels per spectrum. The frequency range can be expanded to any range by switching-in a heterodyne up- or a down-converter. Data from individual instruments are automatically uploaded by FTP to the central server at FHNW. Data which are not locked to UTC (either from the past or from the future) generate an error report.
For more information, including software (which we have), extensive documentation and live data, see https://www.e-callisto.org/ or or https://www.reeve.com/.
The DSES e-Callisto Project
DSES is installing an e-Callisto solar radio spectrometer to monitor space weather (solar radio bursts and X-ray flares). Our log-periodic VHF/UHF antenna has been installed at Haswell, and the sun tracking system is now working. The TV-tuner based receiver has a frequency range of 45-870 MHz. Data will be uploaded every 15 minutes to a university server in Switzerland and available world-wide for analysis. Data are also mirrored to NASA. We are proceeding to install the software, calibrate the system and officially register DSES on the e-Callisto network. The software will run on Windows, Linux or Raspberry Pi, ideally on a low-power, shared computer. This space weather station equipment was funded in part by the ARDC grant for the new building.
The picture above shows Ray Uberecken AA0L working on the DSES e-Callisto antenna on April 14, 2025. The antenna is located behind the new DSES building near Haswell Colorado. The picture was taken by Bill Miller KC0FHN. The single-rotor solar-tracking antenna is designed to follow the Sun’s apparent motion across the sky using only one axis of rotation, the azimuth (east–west) direction, while keeping the elevation (tilt) fixed or optimized for the average solar altitude. The elevation (tilt) can be fixed at the site’s latitude angle to maximize daily solar exposure, but can also be manually adjusted seasonally, if desired. it uses an Arduino microcontroller running a solar-position algorithm to move the antenna a few times a day.