| One of the main goals of LOFAR is to characterise the low-frequency emission from the northern sky in unprecedented detail. With this aim the LoTSS team is working towards mapping the 120-160 MHz sky at a sensitivity of ~100 microJy/beam at a resolution of ~5arcsec. Recently the team have made an important first step towards realising this aim with a preliminary data release of images that span 350 square degrees in the region of the HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45d00m00s to 57d00m00s). These images reach a noise level of less than 0.5mJy/beam at a resolution of 25arcsec, they characterise over 44,000 sources, and are significantly more sensitive than those produced by any other large-area low-frequency survey.
This work could not have been done without the incredible efforts of members of the Surveys Key Science Project, many additional collaborators, and the observatory. The recent LoTSS results are described in Shimwell et al. 'The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release' Astronomy & Astrophysics in press ( https://arxiv.org/abs/1611.02700 ) and the mosaics and catalogs can be downloaded from http://lofar.strw.leidenuniv.nl/doku.php .
The LoTSS team is now preparing to demonstrate that the survey can be fully realised and that the ambitious observational targets of routinely imaging the sky with ~100 microJy/beam sensitivity at a resolution of ~5arcsec can be met. A large number of people at institutes across the globe are contributing to the huge steps that are being made in this area and the infrastructure is in now place to rapidly turn raw LOFAR data into the required high quality continuum images using multiple computational facilities to execute the excellent calibration and imaging pipelines that have been developed.