Solar observing system for radio frequencies 5–120 MHz

The Aalto University Metsähovi Radio Observatory (MRO) in Finland installed and started operating a new low-frequency solar radio monitoring instrument in October 2017. The main component of the new system is a crossed dipole antenna, and it uses a Callisto spectrometer as the back-end. The operational range of the new radio telescope is between 5 and 120 MHz, and its main purpose is to detect solar radio bursts. The coverage of MRO solar radio observations now extends from 5 MHz to 37 GHz, enabling studies of solar flares over a very wide frequency range. The first solar radio bursts were detected with the new system in March 2018. In this article, we describe the new system and report the first flare observations.