Low Frequency Array LOFAR is also now under construction, centered in Holland (here, the first completed station), and it too will be large-scale. All told, 30,000 antennas spread across Europe will connect to a central supercomputer. LOFAR will focus on low radio frequencies. Like LSST, it will monitor a large part of the sky on an almost daily basis, enabling it to research transient radio sources. Radio astronomers will explore magnetic fields within nearby galaxies—an open problem—as well as the so-called "epoch of reionization," an enigmatic period when the universe was just a few hundred million years old.