G. H. Heald et al., "The LOFAR Multifrequency Snapshot Sky Survey (MSSS) - I. Survey description and first results," Astronomy & Astrophysics, V582, no. A123, pp1-22, October2015.
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 (RA, DEC)J2000 = (15h,69d). 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.
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