The LOFAR Multifrequency Snapshot Sky Survey (MSSS). I. Survey description and first results

G. H. Heald (1) , R. F. Pizzo (1) , E. Orrú (1) , R. P. Breton (2) , D. Carbone , C. Ferrari , M. J. Hardcastle (3) , W. Jurusik (4) , G. Macario (5) , D. Mulcahy (6) , D. Rafferty , A. Asgekar (1) , M. Brentjens (1) , R. A. Fallows , W. Frieswijk (1) , M. C. Toribio , B. Adebahr , M. Arts , M. R. Bell (6) , A. Bonafede (7) , J. Bray , J. Broderick (6) , T. Cantwell , P. Carroll , Y. Cendes (8) , A. O. Clarke , J. Croston , S. Daiboo (9) , F. de Gasperin (10) , J. Gregson , J. Harwood , T. Hassall , V. Heesen (11) , A. Horneffer , A. J. van Der Horst (8) , M. Iacobelli , V. Jelić , D. Jones , D. Kant , G. Kokotanekov (8) , P. Martin , J. P. Mckean (1) , L. K. Morabito (12) , B. Nikiel-Wroczyński , A. Offringa , V. N. Pandey (1) , M. Pandey-Pommier (13) , M. Pietka , L. Pratley , C. Riseley , A. Rowlinson (14) , J. Sabater , A. M. M. Scaife (11) , L. H. A. Scheers , K. Sendlinger , A. Shulevski , M. Sipior , C. Sobey (15) , A. J. Stewart (16) , A. Stroe , J. Swinbank (8) , C. Tasse (17) , J. Trüstedt , E. Varenius , S. van Velzen (1) , N. Vilchez (18) , R. J. van Weeren (19) , S. Wijnholds (1) , W. L. Williams (20) , A. G. de Bruyn , R. Nijboer (1) , M. Wise (8) , A. Alexov (1) , J. Anderson , I. M. Avruch (21) , R. Beck , M. E. Bell (6) , I. van Bemmel (1) , M. J. Bentum , G. Bernardi , P. Best , F. Breitling (22) , W. N. Brouw , M. Brüggen (7) , H. R. Butcher (23) , B. Ciardi (24) , J. E. Conway (25) , E. de Geus , A. de Jong , M. de Vos (1) , A. Deller (1) , R.-J. Dettmar (26) , S. Duscha , J. Eislöffel (27) , D. Engels (10) , H. Falcke (28) , R. Fender (6) , M. A. Garrett (20) , Jean-Mathias Griessmeier (29, 30) , A. W. Gunst , J. P. Hamaker , J. W. T. Hessels (8) , M. Hoeft (27) , J. Hörandel (28) , H. A. Holties (1) , H. Intema (20) , N. J. Jackson , E. Jütte , A. Karastergiou , W. F. A. Klijn , V. I. Kondratiev (1) , L. V. E. Koopmans , M. Kuniyoshi (15) , G. Kuper (1) , C. Law (8) , J. van Leeuwen (8, 1) , M. Loose , P. Maat , S. Markoff (8) , R. Mcfadden , D. Mckay-Bukowski , M. Mevius (1) , J. C. A. Miller-Jones , R. Morganti , H. Munk , A. Nelles (28) , J. E. Noordam (1) , M. J. Norden (1) , H. Paas , A. G. Polatidis (1) , W. Reich (15) , A. Renting (1) , H. Röttgering (20) , A. Schoenmakers (1) , D. Schwarz , J. Sluman (1) , O. Smirnov , B. W. Stappers , M. Steinmetz (31) , Michel Tagger (30) , Y. Tang , S. ter Veen (32) , S. Thoudam (28) , R. Vermeulen (1) , C. Vocks (22) , C. Vogt (1) , R. A. M. J. Wijers , O. Wucknitz , S. Yatawatta (1) , P. Zarka (9)

1 ASTRON - Netherlands Institute for Radio Astronomy
2 JBCA - Jodrell Bank Centre for Astrophysics
3 UH - University of Hertfordshire [Hatfield]
4 UJ - Uniwersytet Jagielloński w Krakowie = Jagiellonian University
5 LAGRANGE - Joseph Louis LAGRANGE
6 University of Southampton
7 Jacobs University [Bremen]
8 AI PANNEKOEK - Astronomical Institute Anton Pannekoek
9 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
10 Hamburger Sternwarte/Hamburg Observatory
11 School of Physics and Astronomy [Southampton]
12 Leiden Observatory - Leiden Observatory, Leiden University
13 CRAL - Centre de Recherche Astrophysique de Lyon
14 CSIRO Astronomy and Space Science
15 MPIFR - Max-Planck-Institut für Radioastronomie
16 LASP - Laboratory for Atmospheric and Space Physics [Boulder]
17 LESIA (UMR_8109) - Laboratoire d'études spatiales et d'instrumentation en astrophysique
18 IRAP - Institut de recherche en astrophysique et planétologie
19 CfA - Harvard-Smithsonian Center for Astrophysics
20 Leiden Observatory [Leiden]
21 SRON - SRON Netherlands Institute for Space Research
22 AIP - Leibniz-Institut für Astrophysik Potsdam
23 RSAA - Research School of Astronomy and Astrophysics [Canberra]
24 Max Planck Institute for Astrophysics
25 LANL - Los Alamos National Laboratory
26 Astronomisches Institut der Ruhr-Universität Bochum
27 TLS - Thüringer Landessternwarte Tautenburg
28 Radboud University [Nijmegen]
29 USN - Unité Scientifique de la Station de Nançay
30 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
31 DSMZ - Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures
32 IMAPP - Institute for Mathematics, Astrophysics and Particle Physics

We present the Multifrequency Snapshot Sky Survey (MSSS), the first northern-sky LOFAR imaging survey. In this introductory paper, we first describe in detail the motivation and design of the survey. Compared to previous radio surveys, MSSS is exceptional due to its intrinsic multifrequency nature providing information about the spectral properties of the detected sources over more than two octaves (from 30 to 160 MHz). The broadband frequency coverage, together with the fast survey speed generated by LOFAR's multibeaming capabilities, make MSSS the first survey of the sort anticipated to be carried out with the forthcoming Square Kilometre Array (SKA). Two of the sixteen frequency bands included in the survey were chosen to exactly overlap the frequency coverage of large-area Very Large Array (VLA) and Giant Metrewave Radio Telescope (GMRT) surveys at 74 MHz and 151 MHz respectively. The survey performance is illustrated within the "MSSS Verification Field" (MVF), a region of 100 square degrees centered at J2000 (RA,Dec)=(15h,69deg). The MSSS results from the MVF are compared with previous radio survey catalogs. We assess the flux and astrometric uncertainties in the catalog, as well as the completeness and reliability considering our source finding strategy. We determine the 90% completeness levels within the MVF to be 100 mJy at 135 MHz with 108" resolution, and 550 mJy at 50 MHz with 166" resolution. Images and catalogs for the full survey, expected to contain 150,000-200,000 sources, will be released to a public web server. We outline the plans for the ongoing production of the final survey products, and the ultimate public release of images and source catalogs.

Keywords: Radio continuum: general; Surveys

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]; Sciences of the Universe [physics]

G. H. Heald, R. F. Pizzo, E. Orrú, R. P. Breton, D. Carbone, et al.. The LOFAR Multifrequency Snapshot Sky Survey (MSSS). I. Survey description and first results. Astronomy and Astrophysics - A&A, 2015, 582, pp.A123. ⟨10.1051/0004-6361/201425210⟩. ⟨insu-01343089⟩