LOFAR, the Low Frequency Array, is a new-generation radio telescope under construction in the Netherlands, Germany and other European countries. It is currently becoming operational incrementally. Its unprecedented sensitivity and angular resolution will open a new window to the low-frequency sky that has been largely neglected in the past, owing to the quest for investigations at higher and higher radio frequencies.

“Cosmic Magnetism” is one of six Key Science Projects of LOFAR and is led by German scientists. Synchrotron radiation and its polarisation is one of the main tools of this key project. Low-frequency polarisation observations are challenging and require carefully designed tools for observation, calibration and data analysis. The expected data from the commissioning phase (mid 2010) and from the full LOFAR array (2011) will allow to investigate the distribution and origin of weak, extended magnetic fields in the Milky Way, nearby galaxies and galaxy clusters, and possibly detect magnetic fields from intergalactic filaments for the first time. This Research Unit is to establish a network of experienced German scientists to prepare LOFAR for polarisation observations and for studies of cosmic magnetism.