Long baseline experiments with LOFAR

Abstract

I present first results of LOFAR observations with international baselines. An important cornerstone was the detection of the first long-baseline fringes. Their analysis turns out to be extremely useful to investigate and solve a number of technical issues of the instrument. Crude maps of the sky are created from single-baseline delay/fringe-rate spectra and compared with a short-baseline synthesis map. First long-baseline LBA images are shown of the source 3C196, a bright quasar whose sub-components can only be resolved with the long baselines. The corresponding sub-arcsec HBA image does not show the same amount of details yet, but HBA results are expected to improve significantly very soon. The LBA long-baseline image of 3C196 comprises the highest-resolution radio map ever produced at this low frequency.