Micro-Jy imaging at 150 MHz for the LOFAR EoR project

In its search for neutral hydrogen emission from the Epoch of Reionization, LOFAR has by now accumulated more than 600 hours of radio interferometric data, spread across three target windows: the north celestial pole, 3C 196, and ELAIS-N1. During the past year we improved our calibration and searched for -- and eliminated -- systematic effects in our data and procedures. Although we have not yet detected the signal we are looking for, we have produced by far the deepest and cleanest maps ever made between 115 and 185 MHz. Our 6 arc-second resolution maps reach noise levels between 25 and 80 micro-Jy per beam. We detect thousands of radio sources per field, and find varying amounts of diffuse Galactic polarization in all our target windows. We will present the maps and discuss the most important issues we encountered in producing them.