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1. The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release

Author

Shimwell, T. W., Röttgering, H. J. A., Best, P. N., Williams, W. L., Dijkema, T. J., de Gasperin, F., Hardcastle, M. J., Heald, G. H., Hoang, D. N., Horneffer, A., Intema, H., Mahony, E. K., Mandal, S., Mechev, A. P., Morabito, L., Oonk, J. B. R., Rafferty, D., Retana-Montenegro, E., Sabater, J., Tasse, C., van Weeren, R. J., Brüggen, M., Brunetti, G., Chyży, K. T., Conway, J. E., Haverkorn, M., Jackson, N., Jarvis, M. J., McKean, J. P., Miley, G. K., Morganti, R., White, G. J., Wise, M. W., van Bemmel, I. M., Beck, R., Brienza, M., Bonafede, A., Rivera, G. Calistro, Cassano, R., Clarke, A. O., Cseh, D., Deller, A., Drabent, A., van Driel, W., Engels, D., Falcke, H., Ferrari, C., Fröhlich, S., Garrett, M. A., Harwood, J. J., Heesen, V., Hoeft, M., Horellou, C., Israel, F. P., Kapińska, A. D., Kunert-Bajraszewska, M., McKay, D. J., Mohan, N. R., Orrú, E., Pizzo, R. F., Prandoni, I., Schwarz, D. J., Shulevski, A., Sipior, M., Smith, D. J. B., Sridhar, S. S., Steinmetz, M., Stroe, A., Varenius, E., van der Werf, P. P., Zensus, J. A., and Zwart, J. T. L.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168 MHz imaging survey that will eventually cover the entire Northern sky. Each of the 3170 pointings will be observed for 8 hrs, which, at most declinations, is sufficient to produce ~5arcsec resolution images with a sensitivity of ~0.1mJy/beam and accomplish the main scientific aims of the survey which are to explore the formation and evolution of massive black holes, galaxies, clusters of galaxies and large-scale structure. Due to the compact core and long baselines of LOFAR, the images provide excellent sensitivity to both highly extended and compact emission. For legacy value, the data are archived at high spectral and time resolution to facilitate subarcsecond imaging and spectral line studies. In this paper we provide an overview of the LoTSS. We outline the survey strategy, the observational status, the current calibration techniques, a preliminary data release, and the anticipated scientific impact. The preliminary images that we have released were created using a fully-automated but direction-independent calibration strategy and are significantly more sensitive than those produced by any existing large-area low-frequency survey. In excess of 44,000 sources are detected in the images that have a resolution of 25arcsec, typical noise levels of less than 0.5 mJy/beam, and cover an area of over 350 square degrees in the region of the HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45d00m00s to 57d00m00s)., Comment: 23 pages, 15 figures, 3 tables, accepted for publication in A&A

Published
2016
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2. LBCS: the LOFAR Long-Baseline Calibrator Survey

Author

Jackson, N., Tagore, A., Deller, A., Moldón, J., Varenius, E., Morabito, L., Wucknitz, O., Carozzi, T., Conway, J., Drabent, A., Kapinska, A., Orrù, E., Brentjens, M., Blaauw, R., Kuper, G., Sluman, J., Schaap, J., Vermaas, N., Iacobelli, M., Cerrigone, L., Shulevski, A., ter Veen, S., Fallows, R., Pizzo, R., Sipior, M., Anderson, J., Avruch, M., Bell, M., van Bemmel, I., Bentum, M., Best, P., Bonafede, A., Breitling, F., Broderick, J., Brouw, W., Brüggen, M., Ciardi, B., Corstanje, A., de Gasperin, F., de Geus, E., Eislöffel, J., Engels, D., Falcke, H., Garrett, M., Griessmeier, J., Gunst, A., van Haarlem, M., Heald, G., Hoeft, M., Hörandel, J., Horneffer, A., Intema, H., Juette, E., Kuniyoshi, M., van Leeuwen, J., Loose, G., Maat, P., McFadden, R., McKay-Bukowski, D., McKean, J., Mulcahy, D., Munk, H., Pandey-Pommier, M., Polatidis, A., Reich, W., Röttgering, H., Rowlinson, A., Scaife, A., Schwarz, D., Steinmetz, M., Swinbank, J., Thoudam, S., Toribio, M., Vermeulen, R., Vocks, C., van Weeren, R., Wise, M., Yatawatta, S., and Zarka, P.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

(abridged). We outline LBCS (the LOFAR Long-Baseline Calibrator Survey), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines >1000 km. Suitable sources must contain significant correlated flux density (50-100mJy) at frequencies around 110--190~MHz on scales of a few hundred mas. At least for the 200--300-km international baselines, we find around 1 suitable calibrator source per square degree over a large part of the northern sky, in agreement with previous work. This should allow a randomly selected target to be successfully phase calibrated on the international baselines in over 50% of cases. Products of the survey include calibrator source lists and fringe-rate and delay maps of wide areas -- typically a few degrees -- around each source. The density of sources with significant correlated flux declines noticeably with baseline length over the range 200--600~km, with good calibrators on the longest baselines appearing only at the rate of 0.5 per square degree. Coherence times decrease from 1--3 minutes on 200-km baselines to about 1 minute on 600-km baselines, suggesting that ionospheric phase variations contain components with scales of a few hundred kilometres. The longest median coherence time, at just over 3 minutes, is seen on the DE609 baseline, which at 227km is close to being the shortest. We see median coherence times of between 80 and 110 seconds on the four longest baselines (580--600~km), and about 2 minutes for the other baselines. The success of phase transfer from calibrator to target is shown to be influenced by distance, in a manner that suggests a coherence patch at 150-MHz of the order of 1 degree., Comment: Accepted by Astronomy & Astrophysics. Error in figure 6 corrected

Published
2016
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3. The LOFAR Multifrequency Snapshot Sky Survey (MSSS) I. Survey description and first results

Author

Heald, G. H., Pizzo, R. F., Orrú, E., Breton, R. P., Carbone, D., Ferrari, C., Hardcastle, M. J., Jurusik, W., Macario, G., Mulcahy, D., Rafferty, D., Asgekar, A., Brentjens, M., Fallows, R. A., Frieswijk, W., Toribio, M. C., Adebahr, B., Arts, M., Bell, M. R., Bonafede, A., Bray, J., Broderick, J., Cantwell, T., Carroll, P., Cendes, Y., Clarke, A. O., Croston, J., Daiboo, S., de Gasperin, F., Gregson, J., Harwood, J., Hassall, T., Heesen, V., Horneffer, A., van der Horst, A. J., Iacobelli, M., Jelić, V., Jones, D., Kant, D., Kokotanekov, G., Martin, P., McKean, J. P., Morabito, L. K., Nikiel-Wroczyński, B., Offringa, A., Pandey, V. N., Pandey-Pommier, M., Pietka, M., Pratley, L., Riseley, C., Rowlinson, A., Sabater, J., Scaife, A. M. M., Scheers, L. H. A., Sendlinger, K., Shulevski, A., Sipior, M., Sobey, C., Stewart, A. J., Stroe, A., Swinbank, J., Tasse, C., Trüstedt, J., Varenius, E., van Velzen, S., Vilchez, N., van Weeren, R. J., Wijnholds, S., Williams, W. L., de Bruyn, A. G., Nijboer, R., Wise, M., Alexov, A., Anderson, J., Avruch, I. M., Beck, R., Bell, M. E., van Bemmel, I., Bentum, M. J., Bernardi, G., Best, P., Breitling, F., Brouw, W. N., Brüggen, M., Butcher, H. R., Ciardi, B., Conway, J. E., de Geus, E., de Jong, A., de Vos, M., Deller, A., Dettmar, R. J., Duscha, S., Eislöffel, J., Engels, D., Falcke, H., Fender, R., Garrett, M. A., Grießmeier, J., Gunst, A. W., Hamaker, J. P., Hessels, J. W. T., Hoeft, M., Hörandel, J., Holties, H. A., Intema, H., Jackson, N. J., Jütte, E., Karastergiou, A., Klijn, W. F. A., Kondratiev, V. I., Koopmans, L. V. E., Kuniyoshi, M., Kuper, G., Law, C., van Leeuwen, J., Loose, M., Maat, P., Markoff, S., McFadden, R., McKay-Bukowski, D., Mevius, M., Miller-Jones, J. C. A., Morganti, R., Munk, H., Nelles, A., Noordam, J. E., Norden, M. J., Paas, H., Polatidis, A. G., Reich, W., Renting, A., Röttgering, H., Schoenmakers, A., Schwarz, D., Sluman, J., Smirnov, O., Stappers, B. W., Steinmetz, M., Tagger, M., Tang, Y., ter Veen, S., Thoudam, S., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R. A. M. J., Wucknitz, O., Yatawatta, S., and Zarka, P.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

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., Comment: 23 pages, 19 figures. Accepted for publication in Astronomy & Astrophysics. MSSS Verification Field images and catalog data may be downloaded from http://vo.astron.nl

Published
2015
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4. Star cluster disruption by giant molecular clouds

Author

Gieles, M., Zwart, S. F. Portegies, Baumgardt, H., Athanassoula, E., Lamers, H. J. G. L. M., Sipior, M., and Leenaarts, J.

Subjects
Astrophysics
Abstract

We investigate encounters between giant molecular clouds (GMCs) and star clusters. We propose a single expression for the energy gain of a cluster due to an encounter with a GMC, valid for all encounter distances and GMC properties. This relation is verified with N-body simulations of cluster-GMC encounters and excellent agreement is found. The fractional mass loss from the cluster is 0.25 times the fractional energy gain. This is because 75% of the injected energy goes to the velocities of escaping stars, that are higher than the escape velocity. We derive an expression for the cluster disruption time (t_dis) based on the mass loss from the simulations, taking into account the effect of gravitational focusing by the GMC. The disruption time depends on the cluster mass (M_c) and half-mass radius (r_h) as t_dis=2.0 S (M_c/10^4 M_sun)(3.75 pc/r_h)^3 Gyr, with S=1 for the solar neighbourhood and inversely proportional to the GMC density. The observed shallow relation between cluster radius and mass gives t_dis a power-law dependence on the mass with index 0.7, similar to that found from observations and from simulations of clusters dissolving in tidal fields (0.62). The constant of 2.0 Gyr is about a factor of 3.5 shorter than found from earlier simulations of clusters dissolving under the combined effect of galactic tidal field and stellar evolution. It is somewhat higher than the observationally determined value of 1.3 Gyr. It suggests, however, that the combined effect of tidal field and encounters with GMCs can explain the lack of old open clusters in the solar neighbourhood. GMC encounters can also explain the (very) short disruption time that was observed for star clusters in the central region of M51, since there rho_n is an order of magnitude higher than in the solar neighbourhood., Comment: 14 pages, 13 figures, accepted for publication in MNRAS

Published
2006
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5. Recycled pulsars with black hole companions: the high mass analogues of PSR B2303+46

Author

Sipior, M. S., Zwart, S. Portegies, and Nelemans, G.

Subjects
Astrophysics
Abstract

We investigate the possibility that mass transfer early in the evolution of a massive binary can effect a reversal of the end states of the two components, resulting in a neutron star which forms before a black hole. In this sense, such systems would comprise the high-mass analogues of white dwarf-neutron star systems such as PSR B2303+46. One consequence of this reversal is that a second episode of mass transfer from the black hole progenitor star can recycle the nascent neutron star, extending the life of the pulsar. An estimate of the formation rate through this channel is first performed via a simple analytical approach, and then refined using the results of the SeBa binary evolution package. The central role of kicks in determining the survival rate of these binaries is clearly demonstrated. The final result is expressed in terms of the number of field pulsars one can expect for every single neutron star-black hole (ns,bh) binary. We also calculate this figure for black hole-neutron star (bh,ns) systems formed through the usual channel. Assuming kicks drawn from the distribution of Cordes & Chernoff (1998), we find an expectation value of one (ns,bh) binary per 4 x 10^4 pulsars, and one (bh,ns) system for every 1500 pulsars. This helps to explain why neither system has been seen to date, though it suggests that detection of a (bh,ns) binary is imminent., Comment: 5 pages, 2 eps figures

Published
2004
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6. Simulating the Early Evolution of the Hard X-Ray Properties of a Young Stellar Population

Author

Sipior, M. S., Eracleous, M., and Sigurdsson, S.

Subjects
Astrophysics
Abstract

We present an X-ray binary population synthesis model, and use it to simulate the evolution of X-ray binaries formed in a burst of star formation of duration 20 Myr and star-formation rate 10 M_sun/yr. Our goal is to explain the hard (2-10 keV) X-ray properties of populations of extragalactic X-ray binaries recently observed by the Chandra X-Ray Observatory, especially those associated with recent or ongoing episodes of vigorous star formation. Our simulated X-ray binary population reaches a maximum 2-10 keV luminosity of ~4e40 erg/s after approximately 20 Myr. The X-ray luminous phase is sustained for a period of several hundreds of Myr by succeeding populations of systems with lighter secondary stars, i.e., it persists long after the star-formation episode has ended. These results are insensitive to the poorly-constrained values of the initial mass function and the average mass ratio between accreting and donor stars. The computed peak X-ray luminosity is consistent with observationally-derived correlations between the star-formation rate and the observed hard X-ray luminosity. Model cumulative luminosity functions at the earliest times have power-law indices in agreement with those derived from observations of actively star-forming galaxies. The model cumulative luminosity functions become increasingly steeper with time as the most luminous systems die off, which offers an explanation for the difference in the slopes of observed cumulative luminosity functions of young and old stellar populations., Comment: Submitted to the Astrophysical Journal (40 pages, including 13 figures)

Published
2003

7. The LOFAR Two-metre Sky Survey:I. Survey description and preliminary data release

Author

Shimwell, T. W. (T. W.), Rottgering, H. J. (H. J. A.), Best, P. N. (P. N.), Williams, W. L. (W. L.), Dijkema, T. J. (T. J.), de Gasperin, F. (F.), Hardcastle, M. J. (M. J.), Heald, G. H. (G. H.), Hoang, D. N. (D. N.), Horneffer, A. (A.), Intema, H. (H.), Mahony, E. K. (E. K.), Mandal, S. (S.), Mechev, A. P. (A. P.), Morabito, L. (L.), Oonk, J. B. (J. B. R.), Rafferty, D. (D.), Retana-Montenegro, E. (E.), Sabater, J. (J.), Tasse, C. (C.), van Weeren, R. J. (R. J.), Brueggen, M. (M.), Brunetti, G. (G.), Chyzy, K. T. (K. T.), Conway, J. E. (J. E.), Haverkorn, M. (M.), Jackson, N. (N.), Jarvis, M. J. (M. J.), McKean, J. P. (J. P.), Miley, G. K. (G. K.), Morganti, R. (R.), White, G. J. (G. J.), Wise, M. W. (M. W.), van Bemmel, I. M. (I. M.), Beck, R. (R.), Brienza, M. (M.), Bonafede, A. (A.), Rivera, G. C. (G. Calistro), Cassano, R. (R.), Clarke, A. O. (A. O.), Cseh, D. (D.), Deller, A. (A.), Drabent, A. (A.), van Driel, W. (W.), Engels, D. (D.), Falcke, H. (H.), Ferrari, C. (C.), Froehlich, S. (S.), Garrett, M. A. (M. A.), Harwood, J. J. (J. J.), Heesen, V. (V.), Hoeft, M. (M.), Horellou, C. (C.), Israel, F. P. (F. P.), Kapinska, A. D. (A. D.), Kunert-Bajraszewska, M. (M.), McKay, D. J. (D. J.), Mohan, N. R. (N. R.), Orru, E. (E.), Pizzo, R. F. (R. F.), Prandoni, I. (I.), Schwarz, D. J. (D. J.), Shulevski, A. (A.), Sipior, M. (M.), Smith, D. J. (D. J. B.), Sridhar, S. S. (S. S.), Steinmetz, M. (M.), Stroe, A. (A.), Varenius, E. (E.), van der Werf, P. P. (P. P.), Zensus, J. A. (J. A.), Zwart, J. T. (J. T. L.), Shimwell, T. W. (T. W.), Rottgering, H. J. (H. J. A.), Best, P. N. (P. N.), Williams, W. L. (W. L.), Dijkema, T. J. (T. J.), de Gasperin, F. (F.), Hardcastle, M. J. (M. J.), Heald, G. H. (G. H.), Hoang, D. N. (D. N.), Horneffer, A. (A.), Intema, H. (H.), Mahony, E. K. (E. K.), Mandal, S. (S.), Mechev, A. P. (A. P.), Morabito, L. (L.), Oonk, J. B. (J. B. R.), Rafferty, D. (D.), Retana-Montenegro, E. (E.), Sabater, J. (J.), Tasse, C. (C.), van Weeren, R. J. (R. J.), Brueggen, M. (M.), Brunetti, G. (G.), Chyzy, K. T. (K. T.), Conway, J. E. (J. E.), Haverkorn, M. (M.), Jackson, N. (N.), Jarvis, M. J. (M. J.), McKean, J. P. (J. P.), Miley, G. K. (G. K.), Morganti, R. (R.), White, G. J. (G. J.), Wise, M. W. (M. W.), van Bemmel, I. M. (I. M.), Beck, R. (R.), Brienza, M. (M.), Bonafede, A. (A.), Rivera, G. C. (G. Calistro), Cassano, R. (R.), Clarke, A. O. (A. O.), Cseh, D. (D.), Deller, A. (A.), Drabent, A. (A.), van Driel, W. (W.), Engels, D. (D.), Falcke, H. (H.), Ferrari, C. (C.), Froehlich, S. (S.), Garrett, M. A. (M. A.), Harwood, J. J. (J. J.), Heesen, V. (V.), Hoeft, M. (M.), Horellou, C. (C.), Israel, F. P. (F. P.), Kapinska, A. D. (A. D.), Kunert-Bajraszewska, M. (M.), McKay, D. J. (D. J.), Mohan, N. R. (N. R.), Orru, E. (E.), Pizzo, R. F. (R. F.), Prandoni, I. (I.), Schwarz, D. J. (D. J.), Shulevski, A. (A.), Sipior, M. (M.), Smith, D. J. (D. J. B.), Sridhar, S. S. (S. S.), Steinmetz, M. (M.), Stroe, A. (A.), Varenius, E. (E.), van der Werf, P. P. (P. P.), Zensus, J. A. (J. A.), and Zwart, J. T. (J. T. L.)

Abstract

The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120–168 MHz imaging survey that will eventually cover the entire northern sky. Each of the 3170 pointings will be observed for 8 h, which, at most declinations, is sufficient to produce ~5″ resolution images with a sensitivity of ~100 μJy/beam and accomplish the main scientific aims of the survey, which are to explore the formation and evolution of massive black holes, galaxies, clusters of galaxies and large-scale structure. Owing to the compact core and long baselines of LOFAR, the images provide excellent sensitivity to both highly extended and compact emission. For legacy value, the data are archived at high spectral and time resolution to facilitate subarcsecond imaging and spectral line studies. In this paper we provide an overview of the LoTSS. We outline the survey strategy, the observational status, the current calibration techniques, a preliminary data release, and the anticipated scientific impact. The preliminary images that we have released were created using a fully automated but direction-independent calibration strategy and are significantly more sensitive than those produced by any existing large-area low-frequency survey. In excess of 44 000 sources are detected in the images that have a resolution of 25″, typical noise levels of less than 0.5 mJy/beam, and cover an area of over 350 square degrees in the region of the HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45°00′00″ to 57°00′00″).

Published
2017

8. The LOFAR Two-metre Sky Survey: I. Survey description and preliminary data release

Author

Shimwell, T., Röttgering, H., Best, P., Williams, W., Dijkema, T., De Gasperin, F., Hardcastle, M., Heald, G., Hoang, D., Horneffer, A., Intema, Hubertus, Mahony, E., Mandal, S., Mechev, A., Morabito, L., Oonk, J., Rafferty, D., Retana-Montenegro, E., Sabater, J., Tasse, C., Van Weeren, R., Brüggen, M., Brunetti, G., Chy, K., Conway, J., Haverkorn, M., Jackson, N., Jarvis, M., McKean, J., Miley, G., Morganti, R., White, G., Wise, M., Van Bemmel, I., Beck, R., Brienza, M., Bonafede, A., Calistro Rivera, G., Cassano, R., Clarke, A., Cseh, D., Deller, A., Drabent, A., Van Driel, W., Engels, D., Falcke, H., Ferrari, C., Fröhlich, S., Garrett, M., Harwood, J., Heesen, V., Hoeft, M., Horellou, C., Israel, F., Kapinska, A., Kunert-Bajraszewska, M., McKay, D., Mohan, N., Orrú, E., Pizzo, R., Prandoni, I., Schwarz, D., Shulevski, A., Sipior, M., Smith, D., Sridhar, S., Steinmetz, M., Stroe, A., Varenius, E., Van Der Werf, P., Zensus, J., Zwart, J., Shimwell, T., Röttgering, H., Best, P., Williams, W., Dijkema, T., De Gasperin, F., Hardcastle, M., Heald, G., Hoang, D., Horneffer, A., Intema, Hubertus, Mahony, E., Mandal, S., Mechev, A., Morabito, L., Oonk, J., Rafferty, D., Retana-Montenegro, E., Sabater, J., Tasse, C., Van Weeren, R., Brüggen, M., Brunetti, G., Chy, K., Conway, J., Haverkorn, M., Jackson, N., Jarvis, M., McKean, J., Miley, G., Morganti, R., White, G., Wise, M., Van Bemmel, I., Beck, R., Brienza, M., Bonafede, A., Calistro Rivera, G., Cassano, R., Clarke, A., Cseh, D., Deller, A., Drabent, A., Van Driel, W., Engels, D., Falcke, H., Ferrari, C., Fröhlich, S., Garrett, M., Harwood, J., Heesen, V., Hoeft, M., Horellou, C., Israel, F., Kapinska, A., Kunert-Bajraszewska, M., McKay, D., Mohan, N., Orrú, E., Pizzo, R., Prandoni, I., Schwarz, D., Shulevski, A., Sipior, M., Smith, D., Sridhar, S., Steinmetz, M., Stroe, A., Varenius, E., Van Der Werf, P., Zensus, J., and Zwart, J.

Published
2017

9. The LOFAR Multifrequency Snapshot Sky Survey (MSSS)

Author

Heald, G., Pizzo, R., Orrú, E., Breton, R., Carbone, D., Ferrari, C., Hardcastle, M., Jurusik, W., Macario, G., Mulcahy, D., Rafferty, D., Asgekar, A., Brentjens, M., Fallows, R., Frieswijk, W., Toribio, M., Adebahr, B., Arts, M., Bell, M., Bonafede, A., Bray, J., Broderick, J., Cantwell, T., Carroll, P., Cendes, Y., Clarke, A., Croston, J., Daiboo, S., de Gasperin, F., Gregson, J., Harwood, J., Hassall, T., Heesen, V., Horneffer, A., van der Horst, A., Iacobelli, M., Jelić, V., Jones, D., Kant, D., Kokotanekov, G., Martin, P., McKean, J., Morabito, L., Nikiel-Wroczyński, B., Offringa, A., Pandey, V., Pandey-Pommier, M., Pietka, M., Pratley, L., Riseley, C., Rowlinson, A., Sabater, J., Scaife, A., Scheers, L., Sendlinger, K., Shulevski, A., Sipior, M., Sobey, C., Stewart, A., Stroe, A., Swinbank, J., Tasse, C., Trüstedt, J., Varenius, E., van Velzen, S., Vilchez, N., van Weeren, R., Wijnholds, S., Williams, W., de Bruyn, A., Nijboer, R., Wise, M., Alexov, A., Anderson, J., Avruch, I., Beck, R., van Bemmel, I., Bentum, M., Bernardi, G., Best, P., Breitling, F., Brouw, W., Brüggen, M., Butcher, H., Ciardi, B., Conway, J., de Geus, E., de Jong, A., de Vos, M., Deller, A., Dettmar, R., Duscha, S., Eislöffel, J., Engels, D., Falcke, H., Fender, R., Garrett, M., Grießmeier, J., Gunst, A., Hamaker, J., Hessels, J., Hoeft, M., Hörandel, J., Holties, H., Intema, H., Jackson, N., Jütte, E., Karastergiou, A., Klijn, W., Kondratiev, V., Koopmans, L., Kuniyoshi, M., Kuper, G., Law, C., van Leeuwen, J., Loose, M., Maat, P., Markoff, S., McFadden, R., McKay-Bukowski, D., Mevius, M., Miller-Jones, J., Morganti, R., Munk, H., Nelles, A., Noordam, J., Norden, M., Paas, H., Polatidis, A., Reich, W., Renting, A., Röttgering, H., Schoenmakers, A., Schwarz, D., Sluman, J., Smirnov, O., Stappers, B., Steinmetz, M., Tagger, M., Tang, Y., ter Veen, S., Thoudam, S., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R., Wucknitz, O., Yatawatta, S., and Zarka, P.

Abstract

We present the Multifrequency Snapshot Sky Survey (MSSS), the first northern-sky Low Frequency Array (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 (α,δ)J2000 = (15h,69°). 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.

Published
2015

10. The LOFAR Two-metre Sky Survey

Author

Shimwell, T. W., primary, Röttgering, H. J. A., additional, Best, P. N., additional, Williams, W. L., additional, Dijkema, T. J., additional, de Gasperin, F., additional, Hardcastle, M. J., additional, Heald, G. H., additional, Hoang, D. N., additional, Horneffer, A., additional, Intema, H., additional, Mahony, E. K., additional, Mandal, S., additional, Mechev, A. P., additional, Morabito, L., additional, Oonk, J. B. R., additional, Rafferty, D., additional, Retana-Montenegro, E., additional, Sabater, J., additional, Tasse, C., additional, van Weeren, R. J., additional, Brüggen, M., additional, Brunetti, G., additional, Chyży, K. T., additional, Conway, J. E., additional, Haverkorn, M., additional, Jackson, N., additional, Jarvis, M. J., additional, McKean, J. P., additional, Miley, G. K., additional, Morganti, R., additional, White, G. J., additional, Wise, M. W., additional, van Bemmel, I. M., additional, Beck, R., additional, Brienza, M., additional, Bonafede, A., additional, Calistro Rivera, G., additional, Cassano, R., additional, Clarke, A. O., additional, Cseh, D., additional, Deller, A., additional, Drabent, A., additional, van Driel, W., additional, Engels, D., additional, Falcke, H., additional, Ferrari, C., additional, Fröhlich, S., additional, Garrett, M. A., additional, Harwood, J. J., additional, Heesen, V., additional, Hoeft, M., additional, Horellou, C., additional, Israel, F. P., additional, Kapińska, A. D., additional, Kunert-Bajraszewska, M., additional, McKay, D. J., additional, Mohan, N. R., additional, Orrú, E., additional, Pizzo, R. F., additional, Prandoni, I., additional, Schwarz, D. J., additional, Shulevski, A., additional, Sipior, M., additional, Smith, D. J. B., additional, Sridhar, S. S., additional, Steinmetz, M., additional, Stroe, A., additional, Varenius, E., additional, van der Werf, P. P., additional, Zensus, J. A., additional, and Zwart, J. T. L., additional

Published
2017
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11. LBCS: The LOFAR Long-Baseline Calibrator Survey

Author

Jackson, N., primary, Tagore, A., additional, Deller, A., additional, Moldón, J., additional, Varenius, E., additional, Morabito, L., additional, Wucknitz, O., additional, Carozzi, T., additional, Conway, J., additional, Drabent, A., additional, Kapinska, A., additional, Orrù, E., additional, Brentjens, M., additional, Blaauw, R., additional, Kuper, G., additional, Sluman, J., additional, Schaap, J., additional, Vermaas, N., additional, Iacobelli, M., additional, Cerrigone, L., additional, Shulevski, A., additional, ter Veen, S., additional, Fallows, R., additional, Pizzo, R., additional, Sipior, M., additional, Anderson, J., additional, Avruch, I. M., additional, Bell, M. E., additional, van Bemmel, I., additional, Bentum, M. J., additional, Best, P., additional, Bonafede, A., additional, Breitling, F., additional, Broderick, J. W., additional, Brouw, W. N., additional, Brüggen, M., additional, Ciardi, B., additional, Corstanje, A., additional, de Gasperin, F., additional, de Geus, E., additional, Eislöffel, J., additional, Engels, D., additional, Falcke, H., additional, Garrett, M. A., additional, Grießmeier, J. M., additional, Gunst, A. W., additional, van Haarlem, M. P., additional, Heald, G., additional, Hoeft, M., additional, Hörandel, J., additional, Horneffer, A., additional, Intema, H., additional, Juette, E., additional, Kuniyoshi, M., additional, van Leeuwen, J., additional, Loose, G. M., additional, Maat, P., additional, McFadden, R., additional, McKay-Bukowski, D., additional, McKean, J. P., additional, Mulcahy, D. D., additional, Munk, H., additional, Pandey-Pommier, M., additional, Polatidis, A. G., additional, Reich, W., additional, Röttgering, H. J. A., additional, Rowlinson, A., additional, Scaife, A. M. M., additional, Schwarz, D. J., additional, Steinmetz, M., additional, Swinbank, J., additional, Thoudam, S., additional, Toribio, M. C., additional, Vermeulen, R., additional, Vocks, C., additional, van Weeren, R. J., additional, Wise, M. W., additional, Yatawatta, S., additional, and Zarka, P., additional

Published
2016
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12. The LOFAR Multifrequency Snapshot Sky Survey (MSSS): I. Survey description and first results

Author

Heald, G., Pizzo, R., Orrú, E., Breton, R., Carbone, D., Ferrari, C., Hardcastle, M., Jurusik, W., Macario, G., Mulcahy, D., Rafferty, D., Asgekar, A., Brentjens, M., Fallows, R., Frieswijk, W., Toribio, M., Adebahr, B., Arts, M., Bell, M., Bonafede, A., Bray, J., Broderick, J., Cantwell, T., Carroll, P., Cendes, Y., Clarke, A., Croston, J., Daiboo, S., de Gasperin, F., Gregson, J., Harwood, J., Hassall, T., Heesen, V., Horneffer, A., van der Horst, A., Iacobelli, M., Jelic, V., Jones, D., Kant, D., Kokotanekov, G., Martin, P., McKean, J., Morabito, L., Nikiel-Wroczynski, B., Offringa, A., Pandey, V., Pandey-Pommier, M., Pietka, M., Pratley, L., Riseley, C., Rowlinson, A., Sabater, J., Scaife, A., Scheers, L., Sendlinger, K., Shulevski, A., Sipior, M., Sobey, Charlotte Anne, Stewart, A., Stroe, A., Swinbank, J., Tasse, C., Trüstedt, J., Varenius, E., van Velzen, S., Vilchez, N., van Weeren, R., Wijnholds, S., Williams, W., De Bruyn, A., Nijboer, R., Wise, M., Alexov, A., Anderson, J., Avruch, I., Beck, R., van Bemmel, I., Bentum, M., Bernardi, G., Best, P., Breitling, F., Brouw, W., Brüggen, M., Butcher, H., Ciardi, B., Conway, J., de Geus, E., de Jong, A., de Vos, M., Deller, A., Dettmar, R., Duscha, S., Eislöffel, J., Engels, D., Falcke, J., Fender, R., Garrett, M., Grießmeier, J., Gunst, A., Hamaker, J., Hessels, J., Hoeft, J., Hörandel, J., Holties, H., Intema, H., Jackson, N., Jütte, E., Karastergiou, A., Klijn, W., Kondratiev, V., Koopmans, L., Kuniyoshi, M., Kuper, G., Law, C., van Leeuwen, J., Loose, M., Markoff, S., McFadden, R., McKay-Bukowski, D., Mevius, M., Miller-Jones, James, Morganti, R., Munk, H., Noordam, J., Norden, M., Pass, H., Polatidis, A., Reich, W., Renting, A., Röttgering, H., Schoenmakers, A., Schwarz, D., Sluman, J., Smirnov, O., Stappers, B., Steinmetz, M., Tagger, M., Tang, Y., ter Veen, S., Thoudam, S., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R., Wucknitz, O., Yatawatta, S., Zarka, P., Nelles, A., Maat, P., Heald, G., Pizzo, R., Orrú, E., Breton, R., Carbone, D., Ferrari, C., Hardcastle, M., Jurusik, W., Macario, G., Mulcahy, D., Rafferty, D., Asgekar, A., Brentjens, M., Fallows, R., Frieswijk, W., Toribio, M., Adebahr, B., Arts, M., Bell, M., Bonafede, A., Bray, J., Broderick, J., Cantwell, T., Carroll, P., Cendes, Y., Clarke, A., Croston, J., Daiboo, S., de Gasperin, F., Gregson, J., Harwood, J., Hassall, T., Heesen, V., Horneffer, A., van der Horst, A., Iacobelli, M., Jelic, V., Jones, D., Kant, D., Kokotanekov, G., Martin, P., McKean, J., Morabito, L., Nikiel-Wroczynski, B., Offringa, A., Pandey, V., Pandey-Pommier, M., Pietka, M., Pratley, L., Riseley, C., Rowlinson, A., Sabater, J., Scaife, A., Scheers, L., Sendlinger, K., Shulevski, A., Sipior, M., Sobey, Charlotte Anne, Stewart, A., Stroe, A., Swinbank, J., Tasse, C., Trüstedt, J., Varenius, E., van Velzen, S., Vilchez, N., van Weeren, R., Wijnholds, S., Williams, W., De Bruyn, A., Nijboer, R., Wise, M., Alexov, A., Anderson, J., Avruch, I., Beck, R., van Bemmel, I., Bentum, M., Bernardi, G., Best, P., Breitling, F., Brouw, W., Brüggen, M., Butcher, H., Ciardi, B., Conway, J., de Geus, E., de Jong, A., de Vos, M., Deller, A., Dettmar, R., Duscha, S., Eislöffel, J., Engels, D., Falcke, J., Fender, R., Garrett, M., Grießmeier, J., Gunst, A., Hamaker, J., Hessels, J., Hoeft, J., Hörandel, J., Holties, H., Intema, H., Jackson, N., Jütte, E., Karastergiou, A., Klijn, W., Kondratiev, V., Koopmans, L., Kuniyoshi, M., Kuper, G., Law, C., van Leeuwen, J., Loose, M., Markoff, S., McFadden, R., McKay-Bukowski, D., Mevius, M., Miller-Jones, James, Morganti, R., Munk, H., Noordam, J., Norden, M., Pass, H., Polatidis, A., Reich, W., Renting, A., Röttgering, H., Schoenmakers, A., Schwarz, D., Sluman, J., Smirnov, O., Stappers, B., Steinmetz, M., Tagger, M., Tang, Y., ter Veen, S., Thoudam, S., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R., Wucknitz, O., Yatawatta, S., Zarka, P., Nelles, A., and Maat, P.

Abstract

We present the Multifrequency Snapshot Sky Survey (MSSS), the first northern-sky Low Frequency Array (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 (a,d)J2000 = (15h,69°). 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.

Published
2015

13. The LOFAR Multifrequency Snapshot Sky Survey (MSSS)

Author

Heald, G. H., primary, Pizzo, R. F., additional, Orrú, E., additional, Breton, R. P., additional, Carbone, D., additional, Ferrari, C., additional, Hardcastle, M. J., additional, Jurusik, W., additional, Macario, G., additional, Mulcahy, D., additional, Rafferty, D., additional, Asgekar, A., additional, Brentjens, M., additional, Fallows, R. A., additional, Frieswijk, W., additional, Toribio, M. C., additional, Adebahr, B., additional, Arts, M., additional, Bell, M. R., additional, Bonafede, A., additional, Bray, J., additional, Broderick, J., additional, Cantwell, T., additional, Carroll, P., additional, Cendes, Y., additional, Clarke, A. O., additional, Croston, J., additional, Daiboo, S., additional, de Gasperin, F., additional, Gregson, J., additional, Harwood, J., additional, Hassall, T., additional, Heesen, V., additional, Horneffer, A., additional, van der Horst, A. J., additional, Iacobelli, M., additional, Jelić, V., additional, Jones, D., additional, Kant, D., additional, Kokotanekov, G., additional, Martin, P., additional, McKean, J. P., additional, Morabito, L. K., additional, Nikiel-Wroczyński, B., additional, Offringa, A., additional, Pandey, V. N., additional, Pandey-Pommier, M., additional, Pietka, M., additional, Pratley, L., additional, Riseley, C., additional, Rowlinson, A., additional, Sabater, J., additional, Scaife, A. M. M., additional, Scheers, L. H. A., additional, Sendlinger, K., additional, Shulevski, A., additional, Sipior, M., additional, Sobey, C., additional, Stewart, A. J., additional, Stroe, A., additional, Swinbank, J., additional, Tasse, C., additional, Trüstedt, J., additional, Varenius, E., additional, van Velzen, S., additional, Vilchez, N., additional, van Weeren, R. J., additional, Wijnholds, S., additional, Williams, W. L., additional, de Bruyn, A. G., additional, Nijboer, R., additional, Wise, M., additional, Alexov, A., additional, Anderson, J., additional, Avruch, I. M., additional, Beck, R., additional, Bell, M. E., additional, van Bemmel, I., additional, Bentum, M. J., additional, Bernardi, G., additional, Best, P., additional, Breitling, F., additional, Brouw, W. N., additional, Brüggen, M., additional, Butcher, H. R., additional, Ciardi, B., additional, Conway, J. E., additional, de Geus, E., additional, de Jong, A., additional, de Vos, M., additional, Deller, A., additional, Dettmar, R.-J., additional, Duscha, S., additional, Eislöffel, J., additional, Engels, D., additional, Falcke, H., additional, Fender, R., additional, Garrett, M. A., additional, Grießmeier, J., additional, Gunst, A. W., additional, Hamaker, J. P., additional, Hessels, J. W. T., additional, Hoeft, M., additional, Hörandel, J., additional, Holties, H. A., additional, Intema, H., additional, Jackson, N. J., additional, Jütte, E., additional, Karastergiou, A., additional, Klijn, W. F. A., additional, Kondratiev, V. I., additional, Koopmans, L. V. E., additional, Kuniyoshi, M., additional, Kuper, G., additional, Law, C., additional, van Leeuwen, J., additional, Loose, M., additional, Maat, P., additional, Markoff, S., additional, McFadden, R., additional, McKay-Bukowski, D., additional, Mevius, M., additional, Miller-Jones, J. C. A., additional, Morganti, R., additional, Munk, H., additional, Nelles, A., additional, Noordam, J. E., additional, Norden, M. J., additional, Paas, H., additional, Polatidis, A. G., additional, Reich, W., additional, Renting, A., additional, Röttgering, H., additional, Schoenmakers, A., additional, Schwarz, D., additional, Sluman, J., additional, Smirnov, O., additional, Stappers, B. W., additional, Steinmetz, M., additional, Tagger, M., additional, Tang, Y., additional, ter Veen, S., additional, Thoudam, S., additional, Vermeulen, R., additional, Vocks, C., additional, Vogt, C., additional, Wijers, R. A. M. J., additional, Wucknitz, O., additional, Yatawatta, S., additional, and Zarka, P., additional

Published
2015
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14. Star cluster disruption by giant molecular clouds

Author

Astrophysics, Afd Astrophysics begr 1/1/17, Sub Experiment. Astrophysics begr 1/1/14, Gieles, M., Portegies Zwart, S.F., BAumgardt, H., Athanassoula, E., Lamers, H.J.G.L.M., Sipior, M., Leenaarts, J., Astrophysics, Afd Astrophysics begr 1/1/17, Sub Experiment. Astrophysics begr 1/1/14, Gieles, M., Portegies Zwart, S.F., BAumgardt, H., Athanassoula, E., Lamers, H.J.G.L.M., Sipior, M., and Leenaarts, J.

Published
2006

18. The LOFAR Two-metre Sky Survey – I. Survey Description and Preliminary Data Release

Author

Shimwell, T. W., Röttgering, H. J. A., Best, P. N., Williams, W. L., Dijkema, T.J., de Gasperin, F., Hardcastle, M. J., Heald, G. H., Hoang, D. N., Horneffer, A., Intema, H., Mahony, E. K., Mandal, S., Mechev, A. P., Morabito, L., Oonk, J. B. R., Rafferty, D., Retana-Montenegro, E., Sabater, J., Tasse, C., van Weeren, R. J., Brüggen, M., Brunetti, G., Chyży, K. T., Conway, J. E., Haverkorn, M., Jackson, N., Jarvis, M. J., McKean, J. P., Miley, G. K., Morganti, R., White, G. J., Wise, M. W., van Bemmel, I. M., Beck, R., Brienza, M., Bonafede, A., Calistro Rivera, G., Cassano, R., Clarke, A. O., Cseh, D., Deller, A., Drabent, A., van Driel, W., Engels, D., Falcke, H., Ferrari, C., Fröhlich, S., Garrett, M. A., Harwood, J. J., Heesen, V., Hoeft, M., Horellou, C., Israel, F. P., Kapińska, A. D., Kunert-Bajraszewska, M., McKay, D. J., Mohan, N. R., Orrú, E., Pizzo, R. F., Prandoni, I., Schwarz, D. J., Shulevski, A., Sipior, M., Smith, D. J. B., Sridhar, S. S., Steinmetz, M., Stroe, A., Varenius, E., van der Werf, P. P., Zensus, J. A., Zwart, J. T. L., Shimwell, T. W., Röttgering, H. J. A., Best, P. N., Williams, W. L., Dijkema, T.J., de Gasperin, F., Hardcastle, M. J., Heald, G. H., Hoang, D. N., Horneffer, A., Intema, H., Mahony, E. K., Mandal, S., Mechev, A. P., Morabito, L., Oonk, J. B. R., Rafferty, D., Retana-Montenegro, E., Sabater, J., Tasse, C., van Weeren, R. J., Brüggen, M., Brunetti, G., Chyży, K. T., Conway, J. E., Haverkorn, M., Jackson, N., Jarvis, M. J., McKean, J. P., Miley, G. K., Morganti, R., White, G. J., Wise, M. W., van Bemmel, I. M., Beck, R., Brienza, M., Bonafede, A., Calistro Rivera, G., Cassano, R., Clarke, A. O., Cseh, D., Deller, A., Drabent, A., van Driel, W., Engels, D., Falcke, H., Ferrari, C., Fröhlich, S., Garrett, M. A., Harwood, J. J., Heesen, V., Hoeft, M., Horellou, C., Israel, F. P., Kapińska, A. D., Kunert-Bajraszewska, M., McKay, D. J., Mohan, N. R., Orrú, E., Pizzo, R. F., Prandoni, I., Schwarz, D. J., Shulevski, A., Sipior, M., Smith, D. J. B., Sridhar, S. S., Steinmetz, M., Stroe, A., Varenius, E., van der Werf, P. P., Zensus, J. A., and Zwart, J. T. L.

Abstract

The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168MHz imaging survey that will eventually cover the entire northern sky. Each of the 3170 pointings will be observed for 8 hrs, which, at most declinations, is sufficient to produce ~5'' resolution images with a sensitivity of ~100 µJy/beam and accomplish the main scientific aims of the survey, which are to explore the formation and evolution of massive black holes, galaxies, clusters of galaxies and large-scale structure. Owing to the compact core and long baselines of LOFAR, the images provide excellent sensitivity to both highly extended and compact emission. For legacy value, the data are archived at high spectral and time resolution to facilitate subarcsecond imaging and spectral line studies. In this paper we provide an overview of the LoTSS. We outline the survey strategy, the observational status, the current calibration techniques, a preliminary data release, and the anticipated scientific impact. The preliminary images that we have released were created using a fully automated but direction-independent calibration strategy and are significantly more sensitive than those produced by any existing large-area low-frequency survey. In excess of 44,000 sources are detected in the images that have a resolution of 25'', typical noise levels of less than 0.5 mJy/beam, and cover an area of over 350 square degrees in the region of the HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45°00'00'' to 57°00'00'').

19. The LOFAR Two-metre Sky Survey – I. Survey Description and Preliminary Data Release

Author

Shimwell, T. W., Röttgering, H. J. A., Best, P. N., Williams, W. L., Dijkema, T.J., de Gasperin, F., Hardcastle, M. J., Heald, G. H., Hoang, D. N., Horneffer, A., Intema, H., Mahony, E. K., Mandal, S., Mechev, A. P., Morabito, L., Oonk, J. B. R., Rafferty, D., Retana-Montenegro, E., Sabater, J., Tasse, C., van Weeren, R. J., Brüggen, M., Brunetti, G., Chyży, K. T., Conway, J. E., Haverkorn, M., Jackson, N., Jarvis, M. J., McKean, J. P., Miley, G. K., Morganti, R., White, G. J., Wise, M. W., van Bemmel, I. M., Beck, R., Brienza, M., Bonafede, A., Calistro Rivera, G., Cassano, R., Clarke, A. O., Cseh, D., Deller, A., Drabent, A., van Driel, W., Engels, D., Falcke, H., Ferrari, C., Fröhlich, S., Garrett, M. A., Harwood, J. J., Heesen, V., Hoeft, M., Horellou, C., Israel, F. P., Kapińska, A. D., Kunert-Bajraszewska, M., McKay, D. J., Mohan, N. R., Orrú, E., Pizzo, R. F., Prandoni, I., Schwarz, D. J., Shulevski, A., Sipior, M., Smith, D. J. B., Sridhar, S. S., Steinmetz, M., Stroe, A., Varenius, E., van der Werf, P. P., Zensus, J. A., Zwart, J. T. L., Shimwell, T. W., Röttgering, H. J. A., Best, P. N., Williams, W. L., Dijkema, T.J., de Gasperin, F., Hardcastle, M. J., Heald, G. H., Hoang, D. N., Horneffer, A., Intema, H., Mahony, E. K., Mandal, S., Mechev, A. P., Morabito, L., Oonk, J. B. R., Rafferty, D., Retana-Montenegro, E., Sabater, J., Tasse, C., van Weeren, R. J., Brüggen, M., Brunetti, G., Chyży, K. T., Conway, J. E., Haverkorn, M., Jackson, N., Jarvis, M. J., McKean, J. P., Miley, G. K., Morganti, R., White, G. J., Wise, M. W., van Bemmel, I. M., Beck, R., Brienza, M., Bonafede, A., Calistro Rivera, G., Cassano, R., Clarke, A. O., Cseh, D., Deller, A., Drabent, A., van Driel, W., Engels, D., Falcke, H., Ferrari, C., Fröhlich, S., Garrett, M. A., Harwood, J. J., Heesen, V., Hoeft, M., Horellou, C., Israel, F. P., Kapińska, A. D., Kunert-Bajraszewska, M., McKay, D. J., Mohan, N. R., Orrú, E., Pizzo, R. F., Prandoni, I., Schwarz, D. J., Shulevski, A., Sipior, M., Smith, D. J. B., Sridhar, S. S., Steinmetz, M., Stroe, A., Varenius, E., van der Werf, P. P., Zensus, J. A., and Zwart, J. T. L.

Abstract

The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168MHz imaging survey that will eventually cover the entire northern sky. Each of the 3170 pointings will be observed for 8 hrs, which, at most declinations, is sufficient to produce ~5'' resolution images with a sensitivity of ~100 µJy/beam and accomplish the main scientific aims of the survey, which are to explore the formation and evolution of massive black holes, galaxies, clusters of galaxies and large-scale structure. Owing to the compact core and long baselines of LOFAR, the images provide excellent sensitivity to both highly extended and compact emission. For legacy value, the data are archived at high spectral and time resolution to facilitate subarcsecond imaging and spectral line studies. In this paper we provide an overview of the LoTSS. We outline the survey strategy, the observational status, the current calibration techniques, a preliminary data release, and the anticipated scientific impact. The preliminary images that we have released were created using a fully automated but direction-independent calibration strategy and are significantly more sensitive than those produced by any existing large-area low-frequency survey. In excess of 44,000 sources are detected in the images that have a resolution of 25'', typical noise levels of less than 0.5 mJy/beam, and cover an area of over 350 square degrees in the region of the HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45°00'00'' to 57°00'00'').

20. LBCS: The LOFAR Long-Baseline Calibrator Survey

Author

Rebecca McFadden, G. M. Loose, J. van Leeuwen, J. Schaap, N. J. Vermaas, M. P. van Haarlem, Philip Best, M. Sipior, E. de Geus, E. Juette, D. Engels, Sarod Yatawatta, J. Moldón, George Heald, Anna M. M. Scaife, C. Vocks, F. Breitling, M. Iacobelli, L. Cerrigone, D. D. Mulcahy, H. J. A. Röttgering, Matthias Hoeft, John D. Swinbank, Jean-Mathias Griessmeier, W. Reich, P. Maat, James M. Anderson, M. A. Garrett, Amitpal S. Tagore, I. van Bemmel, J. Sluman, Roberto Pizzo, R. Vermeulen, Marcus Brüggen, Satyendra Thoudam, Aleksandar Shulevski, R. Blaauw, M. C. Toribio, Emanuela Orrú, A. Horneffer, R. J. van Weeren, W. N. Brouw, Martin Bell, M. Avruch, Michael W. Wise, Jörg R. Hörandel, D. McKay-Bukowski, Jochen Eislöffel, Gerard H. Kuper, P. Zarka, Adam Deller, A. Drabent, Mark J. Bentum, Arthur Corstanje, Dominik J. Schwarz, Matthias Steinmetz, F. de Gasperin, Richard Fallows, H. Munk, A. G. Polatidis, Tobia Carozzi, Annalisa Bonafede, S. ter Veen, Leah K. Morabito, A. W. Gunst, John Conway, Anna D. Kapińska, Huib Intema, Heino Falcke, J. W. Broderick, M. Pandey-Pommier, Neal Jackson, Antonia Rowlinson, John McKean, Michiel A. Brentjens, B. Ciardi, Eskil Varenius, O. Wucknitz, M. Kuniyoshi, School of Physics and Astronomy [Manchester], University of Manchester [Manchester], Netherlands Institute for Radio Astronomy (ASTRON), Departament d'Astronomia i Meteorologia [Barcelona], Universitat de Barcelona (UB), Onsala Space Observatory, Dept. of Radio and Space Science, Chalmers University of Technology, Chalmers University of Technology [Göteborg], ARC Centre of Excellence for Autonomous Systems (CAS), University of Technology Sydney (UTS), Swedish Institute of Space Physics [Uppsala] (IRF), Department of Pure Mathematics and Mathematical Statistics (DPMMS), Faculty of mathematics Centre for Mathematical Sciences [Cambridge] (CMS), University of Cambridge [UK] (CAM)-University of Cambridge [UK] (CAM), Department of Astrophysics [Nijmegen], Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen]-Radboud university [Nijmegen], GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), Newcastle University [Newcastle], Joint Institute for VLBI in Europe (JIVE ERIC), University of Hamburg, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Leibniz-Institut für Astrophysik Potsdam (AIP), Oxford Astrophysics, University of Oxford [Oxford], University of Southampton, Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], University of Edinburgh, Radboud university [Nijmegen], Thüringer Landessternwarte Tautenburg (TLS), Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Max-Planck-Institut für Radioastronomie (MPIFR), Astronomisches Institut der Ruhr-Universität Bochum, Ruhr-Universität Bochum [Bochum], National Astronomical Observatory of Japan (NAOJ), Health Service Executive [Dublin] (HSE), Aalborg University [Denmark] (AAU), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Astrophysikalisches Institut Potsdam (AIP), Princeton University, SRON Netherlands Institute for Space Research (SRON), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), European Project: 283393,EC:FP7:INFRA,FP7-INFRASTRUCTURES-2011-1,RADIONET3(2012), High Energy Astrophys. & Astropart. Phys (API, FNWI), Radboud University [Nijmegen]-Radboud University [Nijmegen], Universiteit Leiden, University of Oxford, Radboud University [Nijmegen], Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Jackson, N., Tagore, A., Deller, A., Moldón, J., Varenius, E., Morabito, L., Wucknitz, O., Carozzi, T., Conway, J., Drabent, A., Kapinska, A., Orrù, E., Brentjens, M., Blaauw, R., Kuper, G., Sluman, J., Schaap, J., Vermaas, N., Iacobelli, M., Cerrigone, L., Shulevski, A., Ter Veen, S., Fallows, R., Pizzo, R., Sipior, M., Anderson, J., Avruch, I.M., Bell, M.E., Van Bemmel, I., Bentum, M.J., Best, P., Bonafede, A., Breitling, F., Broderick, J.W., Brouw, W.N., Brüggen, M., Ciardi, B., Corstanje, A., De Gasperin, F., De Geus, E., Eislöffel, J., Engels, D., Falcke, H., Garrett, M.A., Grießmeier, J.M., Gunst, A.W., Van Haarlem, M.P., Heald, G., Hoeft, M., Hörandel, J., Horneffer, A., Intema, H., Juette, E., Kuniyoshi, M., Van Leeuwen, J., Loose, G.M., Maat, P., McFadden, R., McKay-Bukowski, D., McKean, J.P., Mulcahy, D.D., Munk, H., Pandey-Pommier, M., Polatidis, A.G., Reich, W., Röttgering, H.J.A., Rowlinson, A., Scaife, A.M.M., Schwarz, D.J., Steinmetz, M., Swinbank, J., Thoudam, S., Toribio, M.C., Vermeulen, R., Vocks, C., Van Weeren, R.J., Wise, M.W., Yatawatta, S., Zarka, P., and Astronomy

Subjects
Coherence time, media_common.quotation_subject, Astronomy, interferometers [instrumentation], galaxies: active, EWI-27445, Flux, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Radio continuum: galaxie, law.invention, Instrumentation: interferometer, Telescope, surveys, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Range (statistics), Astronomy, Astrophysics and Cosmology, Survey, instrumentation: interferometers, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), media_common, radio continuum: galaxies, Instrumentation:interferometers- Techniques:interferometric - Surveys - Galaxies:active -Radio continuum:galaxies, 020206 networking & telecommunications, Astronomy and Astrophysics, LOFAR, Astronomy and Astrophysic, Geodesy, Astrophysics - Astrophysics of Galaxies, galaxies [radio continuum], Square degree, interferometric [techniques], METIS-319490, Sky, Space and Planetary Science, techniques: interferometric, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), active [galaxies], Environmental science, Astrophysics - Instrumentation and Methods for Astrophysics, IR-102283, Coherence (physics)
Abstract

(abridged). We outline LBCS (the LOFAR Long-Baseline Calibrator Survey), whose aim is to identify sources suitable for calibrating the highest-resolution observations made with the International LOFAR Telescope, which include baselines >1000 km. Suitable sources must contain significant correlated flux density (50-100mJy) at frequencies around 110--190~MHz on scales of a few hundred mas. At least for the 200--300-km international baselines, we find around 1 suitable calibrator source per square degree over a large part of the northern sky, in agreement with previous work. This should allow a randomly selected target to be successfully phase calibrated on the international baselines in over 50% of cases. Products of the survey include calibrator source lists and fringe-rate and delay maps of wide areas -- typically a few degrees -- around each source. The density of sources with significant correlated flux declines noticeably with baseline length over the range 200--600~km, with good calibrators on the longest baselines appearing only at the rate of 0.5 per square degree. Coherence times decrease from 1--3 minutes on 200-km baselines to about 1 minute on 600-km baselines, suggesting that ionospheric phase variations contain components with scales of a few hundred kilometres. The longest median coherence time, at just over 3 minutes, is seen on the DE609 baseline, which at 227km is close to being the shortest. We see median coherence times of between 80 and 110 seconds on the four longest baselines (580--600~km), and about 2 minutes for the other baselines. The success of phase transfer from calibrator to target is shown to be influenced by distance, in a manner that suggests a coherence patch at 150-MHz of the order of 1 degree., Accepted by Astronomy & Astrophysics. Error in figure 6 corrected

Published
2016
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21. The LOFAR Multifrequency Snapshot Sky Survey (MSSS): I. Survey description and first results

Author

G. H. Heald, R. F. Pizzo, E. Orrú, R. P. Breton, D. Carbone, C. Ferrari, M. J. Hardcastle, W. Jurusik, G. Macario, D. Mulcahy, D. Rafferty, A. Asgekar, M. Brentjens, R. A. Fallows, W. Frieswijk, M. C. Toribio, B. Adebahr, M. Arts, M. R. Bell, A. Bonafede, J. Bray, J. Broderick, T. Cantwell, P. Carroll, Y. Cendes, A. O. Clarke, J. Croston, S. Daiboo, F. de Gasperin, J. Gregson, J. Harwood, T. Hassall, V. Heesen, A. Horneffer, A. J. van der Horst, M. Iacobelli, V. Jelić, D. Jones, D. Kant, G. Kokotanekov, P. Martin, J. P. McKean, L. K. Morabito, B. Nikiel-Wroczyński, A. Offringa, V. N. Pandey, M. Pandey-Pommier, M. Pietka, L. Pratley, C. Riseley, A. Rowlinson, J. Sabater, A. M. M. Scaife, L. H. A. Scheers, K. Sendlinger, A. Shulevski, M. Sipior, C. Sobey, A. J. Stewart, A. Stroe, J. Swinbank, C. Tasse, J. Trüstedt, E. Varenius, S. van Velzen, N. Vilchez, R. J. van Weeren, S. Wijnholds, W. L. Williams, A. G. de Bruyn, R. Nijboer, M. Wise, A. Alexov, J. Anderson, I. M. Avruch, R. Beck, M. E. Bell, I. van Bemmel, M. J. Bentum, G. Bernardi, P. Best, F. Breitling, W. N. Brouw, M. Brüggen, H. R. Butcher, B. Ciardi, J. E. Conway, E. de Geus, A. de Jong, M. de Vos, A. Deller, R.-J. Dettmar, S. Duscha, J. Eislöffel, D. Engels, H. Falcke, R. Fender, M. A. Garrett, J. Grießmeier, A. W. Gunst, J. P. Hamaker, J. W. T. Hessels, M. Hoeft, J. Hörandel, H. A. Holties, H. Intema, N. J. Jackson, E. Jütte, A. Karastergiou, W. F. A. Klijn, V. I. Kondratiev, L. V. E. Koopmans, M. Kuniyoshi, G. Kuper, C. Law, J. van Leeuwen, M. Loose, P. Maat, S. Markoff, R. McFadden, D. McKay-Bukowski, M. Mevius, J. C. A. Miller-Jones, R. Morganti, H. Munk, A. Nelles, J. E. Noordam, M. J. Norden, H. Paas, A. G. Polatidis, W. Reich, A. Renting, H. Röttgering, A. Schoenmakers, D. Schwarz, J. Sluman, O. Smirnov, B. W. Stappers, M. Steinmetz, M. Tagger, Y. Tang, S. ter Veen, S. Thoudam, R. Vermeulen, C. Vocks, C. Vogt, R. A. M. J. Wijers, O. Wucknitz, S. Yatawatta, P. Zarka, Heald, G.H., Pizzo, R.F., Orrú, E., Breton, R.P., Carbone, D., Ferrari, C., Hardcastle, M.J., Jurusik, W., Macario, G., Mulcahy, D., Rafferty, D., Asgekar, A., Brentjens, M., Fallows, R.A., Frieswijk, W., Toribio, M.C., Adebahr, B., Arts, M., Bell, M.R., Bonafede, A., Bray, J., Broderick, J., Cantwell, T., Carroll, P., Cendes, Y., Clarke, A.O., Croston, J., Daiboo, S., De Gasperin, F., Gregson, J., Harwood, J., Hassall, T., Heesen, V., Horneffer, A., Van Der Horst, A.J., Iacobelli, M., Jelić, V., Jones, D., Kant, D., Kokotanekov, G., Martin, P., McKean, J.P., Morabito, L.K., Nikiel-Wroczyński, B., Offringa, A., Pandey, V.N., Pandey-Pommier, M., Pietka, M., Pratley, L., Riseley, C., Rowlinson, A., Sabater, J., Scaife, A.M.M., Scheers, L.H.A., Sendlinger, K., Shulevski, A., Sipior, M., Sobey, C., Stewart, A.J., Stroe, A., Swinbank, J., Tasse, C., Trüstedt, J., Varenius, E., Van Velzen, S., Vilchez, N., Van Weeren, R.J., Wijnholds, S., Williams, W.L., De Bruyn, A.G., Nijboer, R., Wise, M., Alexov, A., Anderson, J., Avruch, I.M., Beck, R., Bell, M.E., Van Bemmel, I., Bentum, M.J., Bernardi, G., Best, P., Breitling, F., Brouw, W.N., Brüggen, M., Butcher, H.R., Ciardi, B., Conway, J.E., De Geus, E., De Jong, A., De Vos, M., Deller, A., Dettmar, R.-J., Duscha, S., Eislöffel, J., Engels, D., Falcke, H., Fender, R., Garrett, M.A., Grießmeier, J., Gunst, A.W., Hamaker, J.P., Hessels, J.W.T., Hoeft, M., Hörandel, J., Holties, H.A., Intema, H., Jackson, N.J., Jütte, E., Karastergiou, A., Klijn, W.F.A., Kondratiev, V.I., Koopmans, L.V.E., Kuniyoshi, M., Kuper, G., Law, C., Van Leeuwen, J., Loose, M., Maat, P., Markoff, S., McFadden, R., McKay-Bukowski, D., Mevius, M., Miller-Jones, J.C.A., Morganti, R., Munk, H., Nelles, A., Noordam, J.E., Norden, M.J., Paas, H., Polatidis, A.G., Reich, W., Renting, A., Röttgering, H., Schoenmakers, A., Schwarz, D., Sluman, J., Smirnov, O., Stappers, B.W., Steinmetz, M., Tagger, M., Tang, Y., Ter Veen, S., Thoudam, S., Vermeulen, R., Vocks, C., Vogt, C., Wijers, R.A.M.J., Wucknitz, O., Yatawatta, S., Zarka, P., High Energy Astrophys. & Astropart. Phys (API, FNWI), Netherlands Institute for Radio Astronomy (ASTRON), Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], University of Hertfordshire [Hatfield] (UH), Uniwersytet Jagielloński w Krakowie = Jagiellonian University (UJ), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), University of Southampton, Jacobs University [Bremen], Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Hamburger Sternwarte/Hamburg Observatory, Universität Hamburg (UHH), School of Physics and Astronomy [Southampton], Leiden Observatory, Leiden University (Leiden Observatory), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Max-Planck-Institut für Radioastronomie (MPIFR), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Leiden Observatory [Leiden], Universiteit Leiden, SRON Netherlands Institute for Space Research (SRON), Leibniz-Institut für Astrophysik Potsdam (AIP), Research School of Astronomy and Astrophysics [Canberra] (RSAA), Australian National University (ANU), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Los Alamos National Laboratory (LANL), Astronomisches Institut der Ruhr-Universität Bochum, Ruhr-Universität Bochum [Bochum], Thüringer Landessternwarte Tautenburg (TLS), Radboud University [Nijmegen], Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures (DSMZ), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), ANR-09-JCJC-0001,OPALES(2009), European Project: 247295,EC:FP7:ERC,ERC-2009-AdG,AARTFAAC(2010), European Project: 267697,EC:FP7:ERC,ERC-2010-AdG_20100224,4PI-SKY(2011), ITA, GBR, FRA, DEU, NLD, Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'études européennes et de politique comparée (CEE), Sciences Po (Sciences Po)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Harvard University [Cambridge]-Smithsonian Institution, Universiteit Leiden [Leiden], Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Radboud university [Nijmegen], Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Astronomy, Kapteyn Astronomical Institute, Jodrell Bank Centre for Astrophysics, Jagiellonian University [Krakow] (UJ), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Smithsonian Institution-Harvard University [Cambridge], Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), ANR-09-JCJC-0001,OPALES,nOn-thermal Processes in gALaxy cluStErs(2009), and Database Architectures

Subjects
010504 meteorology & atmospheric sciences, Computer science, Astronomy, media_common.quotation_subject, FOS: Physical sciences, METIS-315082, 01 natural sciences, Radio spectrum, Radio continuum: general, surveys, 0103 physical sciences, radio continuum: general, Survey, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 0105 earth and related environmental sciences, Remote sensing, media_common, Giant Metrewave Radio Telescope, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy and Astrophysics, LOFAR, Astronomy and Astrophysic, Square kilometre array, IR-98663, Sky, [SDU]Sciences of the Universe [physics], Space and Planetary Science, Experimental High Energy Physics, EWI-26540, Snapshot (computer storage), general [radio continuum], Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

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., Comment: 23 pages, 19 figures. Accepted for publication in Astronomy & Astrophysics. MSSS Verification Field images and catalog data may be downloaded from http://vo.astron.nl

Published
2015
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