The LOFAR Two-metre Sky Survey

作者：T. W. Shimwell, M. J. Hardcastle, C. Tasse, P. N. Best, H. J. A. Röttgering, W. L. Williams, A. Botteon, A. Drabent, A. P. Mechev, A. Shulevski, R. J. van Weeren, Hertzog L. Bester, M. Brüggen, G. Brunetti, J. R. Callingham, K. T. Chyży, J. E. Conway, Tammo Jan Dijkema, K. J. Duncan, F. de Gasperin, Catherine Hale, M. Haverkorn, B. Hugo, N. Jackson, M. Mevius, G. K. Miley, L. K. Morabito, R. Morganti, A. R. Offringa, J. B. R. Oonk, D. A. Rafferty, J. Sabater, D. J. B. Smith, Dominik J. Schwarz, O. Smirnov, S. P. O’Sullivan, H. K. Vedantham, G. J. White, Joshua G. Albert, L. Alegre, Bernard Duah Asabere, David Bacon, A. Bonafede, E. Bonnassieux, M. Brienza, Maciej Bilicki, Matteo Bonato, G. Calistro Rivera, R. Cassano, R. K. Cochrane, J. H. Croston, V. Cuciti, D. Dallacasa, A. Danezi, R.‐J. Dettmar, G. Di Gennaro, H. W. Edler, T. A. Enßlin, K. L. Emig, T. M. O. Franzen, Cristina García-Vergara, Y. G. Grange, G. Gürkan, M. Hajduk, G. Heald, V. Heesen, D. N. Hoang, M. Hoeft, C. Horellou, M. Iacobelli, M. Jamrozy, Vibor Jelić, R. Kondapally, Pranav Kukreti, M. Kunert‐Bajraszewska, M. Magliocchetti, V. H. Mahatma, K. Małek, S. Mandal, F. Massaro, Zheng Meyer-Zhao, B. Mingo, R. I. J. Mostert, Dhanya G. Nair, Szymon J. Nakoneczny, B. Nikiel-Wroczyński, E. Orrú, Urszula Pajdosz-Śmierciak, T. Pasini, I. Prandoni, H. E. van Piggelen, K. Rajpurohit, E. Retana-Montenegro, C. J. Riseley, A. Rowlinson, Aayush Saxena, C. Schrijvers, Frits Sweijen, Thilo M. Siewert, R. Timmerman, M. Vaccari, Jacco Vink, Jennifer West, Aleksandra Wołowska, Xiaoyuan Zhang, Jian Zheng · 发表于：Astronomy and Astrophysics · 年份：2022 · DOI：10.1051/0004-6361/202142484 · 被引用次数：482 · 研究领域：Radio Astronomy Observations and Technology、Astrophysics and Cosmic Phenomena、Galaxies: Formation, Evolution, Phenomena

In this data release from the ongoing LOw-Frequency ARray (LOFAR) Two-metre Sky Survey we present 120–168 MHz images covering 27% of the northern sky. Our coverage is split into two regions centred at approximately 12h45m +44°30′ and 1h00m +28°00′ and spanning 4178 and 1457 square degrees respectively. The images were derived from 3451 h (7.6 PB) of LOFAR High Band Antenna data which were corrected for the direction-independent instrumental properties as well as direction-dependent ionospheric distortions during extensive, but fully automated, data processing. A catalogue of 4 396 228 radio sources is derived from our total intensity (Stokes I ) maps, where the majority of these have never been detected at radio wavelengths before. At 6″ resolution, our full bandwidth Stokes I continuum maps with a central frequency of 144 MHz have: a median rms sensitivity of 83 μJy beam −1 ; a flux density scale accuracy of approximately 10%; an astrometric accuracy of 0.2″; and we estimate the point-source completeness to be 90% at a peak brightness of 0.8 mJy beam −1 . By creating three 16 MHz bandwidth images across the band we are able to measure the in-band spectral index of many sources, albeit with an error on the derived spectral index of > ± 0.2 which is a consequence of our flux-density scale accuracy and small fractional bandwidth. Our circular polarisation (Stokes V ) 20″ resolution 120–168 MHz continuum images have a median rms sensitivity of 95 μJy beam −1 , and we estimate...