Lengths and u-v coverage of the baselines used in the LOFAR observations. Top: Distribution of LOFAR baseline lengths between international stations. Core and remote LOFAR stations have baselines up to 100 km, so a gap in the u − v coverage still exists between 100 and 200 km. The longest baseline, 1890 km between Birr (Ireland) and Baldy (Poland) will be exceeded soon with the advent of the station in Irbene (Latvia). Bottom: Snapshot u − v plane coverage for a source at 34° declination.