Long baseline experiments with LOFAR

TL;DR

This paper reports initial results from LOFAR's long-baseline observations, including the first detection of fringes, technical insights, and high-resolution images of a quasar, demonstrating LOFAR's capabilities at low frequencies.

Contribution

It presents the first long-baseline fringes detection with LOFAR and demonstrates high-resolution imaging of a quasar at low frequencies, advancing low-frequency radio interferometry.

Findings

Detection of first long-baseline fringes with LOFAR.

Crude sky maps from delay/fringe-rate spectra.

High-resolution image of quasar 3C196 at low frequency.

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.