2020/11/16 by C. Tasse, T. Shimwell, M. J. Hardcastle +29 · 1 voice
Physics and Astronomy · #astro-ph.IM
paper · pdf · doi:10.1051/0004-6361/202038804
published as A&A 648, A1 (2021) · This paper is part of the 1st data release of the LoTSS Deep Fields. Electronic data catalogues will be made available on journal publication
arxiv published 2020/11/16 · arxiv created 2020/11/19 · arxiv updated 2021/04/07
The Low Frequency Array (LOFAR) is an ideal instrument to conduct deep extragalactic surveys. It has a large field of view and is sensitive to large scale and compact emission. It is, however, very challenging to synthesize thermal noise limited maps at full resolution, mainly because of the complexity of the low-frequency sky and the direction dependent effects (phased array beams and ionosphere). In this first paper of a series we present a new calibration and imaging pipeline that aims at producing high fidelity, high dynamic range images with LOFAR High Band Antenna data, while being computationally efficient and robust against the absorption of unmodeled radio emission. We apply this calibration and imaging strategy to synthesize deep images of the Bootes and LH fields at 150 MHz, totaling ∼80 and ∼100 hours of integration respectively and reaching unprecedented noise levels at these low frequencies of \lesssim30 and \lesssim23 μJy/beam in the inner ∼3 deg2. This approach is also being used to reduce the LoTSS-wide data for the second data release.