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J/A+A/598/A104         LOFAR Two-metre Sky Survey             (Shimwell+, 2017)

The LOFAR Two-metre Sky Survey. I. Survey Description and Preliminary Data Release. Shimwell T.W., Rottgering 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., Bruggen M., Brunetti G., Chyzy 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., Frohlich S., Garrett M.A., Harwood J.J., Heesen V., Hoeft M., Horellou C., Israel F.P., Kapinska A.D., Kunert-Bajraszewska M., McKay D.J., Mohan N.R., Orru 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. <Astron. Astrophys. 598, A104 (2017)> =2017A&A...598A.104S (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Radio continuum Keywords: surveys - catalogs - radio continuum: general - techniques: image processing 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-arcsec 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 25-arcsec, typical noise levels of less than 0.5mJy/beam, and cover an area of over 350 square degrees in the region of the HETDEX Spring Field (right ascension 10:45:00 to 15:30:00 and declination 45:00:00 to 57:00:00). Description: We provide a preliminary data release from the LOFAR Two-metre Sky Survey (LoTSS). This release covers 381 square degrees (right ascension 10:45:00 to 15:30:00 and declination 45:00:00 to 57:00:00) and contains 44,500 sources which were detected with signal in excess of seven times the local noise in our 25" resolution images. The noise varies across the surveyed region but is typically below 0.5mJy/beam and we estimate the catalogue to be 90% complete for sources with flux densities in excess of 3.9mJy/beam. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file lotss.dat 171 44500 Full source catalogue of LoTSS PDR 120-168MHz sources 2880 2136 Catalog in fits
See also: : LoTSS Home Page Byte-by-byte Description of file: lotss.dat
Bytes Format Units Label Explanations
1- 3 A3 --- --- [ILT] 4- 21 A18 --- ILT ILT name without prefix (JHHMMSS.S+DDMMSS.S) (1) 23- 31 F9.5 deg RAdeg Centroid right ascension (J2000) 33- 41 F9.5 arcsec e_RAdeg Statistical uncertainty on right ascension (1 sigma) 43- 51 F9.5 arcsec e_RAdegtot Total uncertainty on right ascension (1 sigma) 53- 61 F9.5 deg DEdeg Centroid declination (J2000) 63- 71 F9.5 arcsec e_DEdeg Statistical uncertainty on declination (1 sigma) 73- 81 F9.5 arcsec e_DEdegtot Total uncertainty on declination (1 sigma) 83- 93 F11.5 mJy/beam FPeak Peak 120-168MHz brightness 95-103 F9.5 mJy/beam e_FPeak Statistical error on peak brightness (1 sigma) 105-115 F11.5 mJy/beam e_FPeaktot Total error on peak brightness (1 sigma) 117-127 F11.5 mJy FTot Integrated 120-168MHz flux density 129-137 F9.5 mJy e_FTot Statistical error on integrated flux density 139-149 F11.5 mJy e_FTottot Total error on integrated flux density 151 A1 --- Resolved Flag indicating whether source is resolved 153-161 F9.5 mJy/beam Islrms Local image background RMS noise 163 A1 --- SCode [SCM] Source structure code (2) 165-171 A7 --- MosaicID Name of the parent mosaic image (3)
Note (1): The full source name including prefix is 'ILTJHHMMSS.s+DDMMSS.s', with HHMMSS.s+DDMMSS.s the centroid coordinates in sexagesimal format. Note (2): The source structure code defines the multiplicity of the source structure in terms of Gaussian components as follows: S = refers to an isolated single-Gaussian source C = refers to a single-Gaussian source partly overlapping with other sources M = is a source fit with multiple Gaussians Note (3): The parent mosaic image in which the source detection was characterised. The mosaic images are provided through the LoTSS website
Acknowledgements: Timothy Shimwell, shimwell(at)
(End) Timothy Shimwell [Leiden Obs], Patricia Vannier [CDS] 07-Feb-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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