POLFAR - Polish incarnation of the LOFAR. Scientific objectives and system realization

Polish astronomers and space scientists are participating in the development and use of a radio astronomical instrument of new generation: Low Frequency ARray - LOFAR, exploring yet poorly studied range of low (<;300 MHz) frequencies. It constitutes a European array of thousands of antennas - a challenge for data transfer and processing techniques. The LOFAR facilities in Poland will be distributed among three sites: Lazy (East of Kraków), Borówiec near Poznań and Baldy near Olsztyn. All they will be connected via PIONIER dedicated links to Poznań. Each site will host one LOFAR station (96 high-band+96 low-band antennas). They will most time work as a part of European network, however, when less charged, they can operate as a national network. LOFAR will study objects in early Universe (like the high-redshift neutral hydrogen) and cosmic plasma in conditions unreachable in earth-based laboratories: densities either very high (pulsars) or extremely low, temperatures ranging from single Kelvins to milions of degrees and a wide range of magnetic field strengths. This research is important for Sun-Earth system plasma monitoring and for plasma technologies. To fulfill the conditions to participate in LOFAR Polish astronomers established the national consortium - POLFAR which also will hosting reference stations for the Global Navigation Satellite System (GNSS).