C.D.S. - SIMBAD4 rel 1.7 - 2020.09.19CEST05:51:21

2018A&A...620A..74R - Astronomy and Astrophysics, volume 620A, 74-74 (2018/12-1)

Deep LOFAR 150 MHz imaging of the Bootes field: Unveiling the faint low-frequency sky.


Abstract (from CDS):

We have conducted a deep survey (with a central rms of 55µJy) with the LOw Frequency ARray (LOFAR) at 120-168MHz of the Bootes field, with an angular resolution of 3.98''x6.45'', and obtained a sample of 10091 radio sources (5σ limit) over an area of 20deg2. The astrometry and flux scale accuracy of our source catalog is investigated. The resolution bias, incompleteness and other systematic effects that could affect our source counts are discussed and accounted for. The derived 150MHz source counts present a flattening below sub-mJy flux densities, that is in agreement with previous results from high- and low- frequency surveys. This flattening has been argued to be due to an increasing contribution of star-forming galaxies and faint active galactic nuclei. Additionally, we use our observations to evaluate the contribution of cosmic variance to the scatter in source counts measurements. The latter is achieved by dividing our Bootes mosaic into 10 non-overlapping circular sectors, each one with an approximate area of 2deg2. The counts in each sector are computed in the same way as done for the entire mosaic. By comparing the induced scatter with that of counts obtained from depth observations scaled to 150MHz, we find that the 1σ scatter due to cosmic variance is larger than the Poissonian errors of the source counts, and it may explain the dispersion from previously reported depth source counts at flux densities S<1mJy. This work demonstrates the feasibility of achieving deep radio imaging at low-frequencies with LOFAR.

Abstract Copyright: © ESO 2018

Journal keyword(s): surveys - catalogs - radio continuum: general - techniques: image processing

VizieR on-line data: <Available at CDS (J/A+A/620/A74): table2.dat list.dat fits/*>

Nomenclature: Table 2: [RRS2018] JHHMMSS.ss+DDMMSS.s N=10091.

Status at CDS : Acronym for new objects described in the dictionary of nomenclature and being created in SIMBAD.

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
1 M 1 SNR 05 34 31.94 +22 00 52.2           ~ 5626 4
2 3C 196 Sy1 08 13 36.056090 +48 13 02.63597   18.36 17.79     ~ 483 2
3 M 87 BiC 12 30 49.42338230 +12 23 28.0438581 10.16 9.59 8.63   7.49 ~ 6255 3
4 3C 295 Sy2 14 11 20.467 +52 12 09.52   22.34 20.80 18.54   ~ 901 5
5 NAME Cyg A Sy2 19 59 28.35645829 +40 44 02.0966496   16.22 15.10     ~ 2124 2
6 NAME Cas A SNR 23 23 24.000 +58 48 54.00           ~ 2428 1

    Equat.    Gal    SGal    Ecl

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