LOFAR 150-MHz observations of the Boötes field: Catalogue and source counts

W.L. Williams, R.J. Van Weeren, H.J.A. Röttgering, P. Best, T.J. Dijkema, F. De Gasperin, M.J. Hardcastle, G. Heald, I. Prandoni, J. Sabater, T.W. Shimwell, C. Tasse, I.M. Van Bemmel, M. Brüggen, G. Brunetti, J.E. Conway, T. Enßlin, D. Engels, H. Falcke, C. FerrariM. Haverkorn, N. Jackson, M.J. Jarvis, Anna Kapińska, E.K. Mahony, G.K. Miley, L.K. Morabito, R. Morganti, E. Orrú, E. Retana-Montenegro, S.S. Sridhar, M.C. Toribio, G.J. White, M.W. Wise, J.T.L. Zwart

Research output: Contribution to journalArticlepeer-review

148 Citations (Scopus)


© The Authors 2016. Published by Oxford University Press on behalf of The Royal Astronomical Society. We present the first wide area (19 deg2), deep (˜120-150 µJy beam-1), high-resolution (5.6 × 7.4 arcsec) LOFAR High Band Antenna image of the Boötes field made at 130-169 MHz. This image is at least an order of magnitude deeper and 3-5 times higher in angular resolution than previously achieved for this field at low frequencies. The observations and data reduction, which includes full direction-dependent calibration, are described here. We present a radio source catalogue containing 6 276 sources detected over an area of 19 deg2, with a peak flux density threshold of 5s. As the first thorough test of the facet calibration strategy, introduced by van Weeren et al., we investigate the flux and positional accuracy of the catalogue. We present differential source counts that reach an order of magnitude deeper in flux density than previously achieved at these low frequencies, and show flattening at 150-MHz flux densities below 10 mJy associated with the rise of the low flux density star-forming galaxies and radio-quiet AGN.
Original languageEnglish
Pages (from-to)2385-2412
Number of pages28
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Early online date29 May 2016
Publication statusPublished - 11 Aug 2016


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