The Low-frequency Array (LOFAR) is a radio telescope operating at 10-240 MHz, aimed at detecting the hydrogen 21-cm line redshifted from the epoch of reionization (much like Murchison Widefield Array) and other low-frequency radio observable phenomena. It was completed in 2012 in Europe and has an effective collecting area of 300,000 square meters. It was built by Netherlands' ASTRON with contributions by other European nations, and is operated by ASTRON.
It consists of separate stations, each station with a number of simple, stationary antennas, the majority in a single 2×3 km tract in the Netherlands (the LOFAR-core) and the rest further afield in the Netherlands and other European countries, providing a 1000-km baseline. Imaging is done using aperture synthesis/phased array techniques.
The LOFAR Two-metre Sky Survey (LoTSS) is a survey in progress of the northern hemisphere at 120-168 MHz, with ongoing identifications of the optical counterparts of the discovered sources.