Abstract: The LOw Frequency ARray (LOFAR) is one of the world’s leading low-frequency radio telescopes. It consists of dozens of stations across Europe—each comprising hundreds of dipole antennas—with a dense core in the Netherlands. While LOFAR is currently undergoing an upgrade to further enhance its sensitivity, it has already produced a broad range of high-quality scientific results both within and beyond traditional radio astronomy. These include among others studies of radio galaxies, large low-frequency sky surveys, the epoch of reionization and cosmic dawn, cosmic magnetism, pulsars and other transient sources, cosmic rays, lightning, and space weather.

Operating between 10 and 240 MHz, LOFAR must contend with the ionosphere—a region of the upper atmosphere partly ionized by solar radiation—which presents a significant challenge for data calibration. The ionosphere distorts passing electromagnetic waves, and turbulent variations in the electron density make it difficult to correct these distortions. LOFAR’s sensitivity to even the smallest ionospheric structures, though often problematic for astronomers, also offers a unique opportunity: it allows us to probe these fine-scale features directly and gain new insights into ionospheric plasma processes.

In this presentation, I will provide an overview of the LOFAR system and its scientific capabilities, followed by a closer look at the ionospheric data products the telescope can deliver.