J/A+A/648/A2 LOFAR Two-metre Sky Survey Deep Fields DR1 (Sabater+, 2021)
The LOFAR Two Metre Sky Survey: Deep Fields Data Release 1.
II. The ELAIS-N1 LOFAR deep field.
Sabater J., Best P.N., Tasse C., Hardcastle M.J., Shimwell T.W., Nisbet D.,
Jelic V., Callingham J.R., Roettgering H.J.A., Bonato M., Bondi M.,
Ciardi B., Cochrane R.K., Jarvis M.J., Kondapally R., Koopmans L.V.E.,
O'Sullivan S.P., Prandoni I., Schwarz D.J., Smith D.J.B., Wang L.,
Williams W.L., Zaroubi S.
<Astron. Astrophys. 648, A2 (2021)>
=2021A&A...648A...2S 2021A&A...648A...2S (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Radio sources ; Galaxy catalogs
Keywords: surveys - catalogs - radio continuum: general -
radio continuum: galaxies
Abstract:
The LOFAR Two-metre Sky Survey (LoTSS) will cover the full northern
sky and, additionally, aims to observe the LoTSS deep fields to a
noise level of ≲10uJy/beam over several tens of square degrees in
areas that have the most extensive ancillary data. This paper presents
the ELAIS-N1 deep field, the deepest of the LoTSS deep fields to date.
With an effective observing time of 163.7 hours, it reaches a root
mean square (RMS) noise level of ≲20uJy/beam in the central region
(and below 30uJy/beam over 10 square degrees). The resolution is 6
arcsecs and 84862 radio sources were detected in the full area (68
square degrees) with 74127 sources in the highest quality area at less
than 3 degrees from the pointing centre. The observation reaches a sky
density of more than 5000 sources per square degree in the central
region (5 square degrees).We present the calibration procedure, which
addresses the special configuration of some observations and the
extended bandwidth covered (115 to 177MHz; central frequency 146.2MHz)
compared to standard LoTSS. We also describe the methods used to
calibrate the flux density scale using cross-matching with sources
detected by other radio surveys in the literature. We find the flux
density uncertainty related to the flux density scale to be 6.5 per
cent. By studying the variations of the flux density measurements
between different epochs, we show that relative flux density
calibration is reliable out to about a 3 degree radius, but that
additional flux density uncertainty is present for all sources at
about the 3 per cent level; this is likely to be associated with
residual calibration errors, and is shown to be more significant in
datasets with poorer ionosphere conditions. We also provide intra-band
spectral indices, which can be useful to detect sources with unusual
spectral properties. The final uncertainty in the flux densities is
estimated to be 10 per cent for ELAIS-N1.
Description:
The ELAIS-N1 data presented in this paper were taken in the LOFAR
observation cycles 0, 2, and 4 (proposals LC0_019, LC2_024, and,
LC4_008 respectively) from May 2013 to August 2015.
To produce the final radio catalogues the image was scaled by the
scaling factor determined in the previous section (0.796 for the deep
image) and PyBDSF was run again using the same parameters. A catalogue
of sources and a catalogue of individual Gaussians are produced. The
columns of the catalogues are those of a typical PyBDSF default output
including the position, integrated and peak flux density, structural
parameters (raw and deconvolved) and their estimated errors.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 579 84862 Deep radio catalog
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See also:
J/A+A/648/A3 : LOFAR Two-metre Sky Survey Deep Fields DR1 (Kondapally+, 2021)
J/A+A/648/A4 : LoTSS Deep Fields DR1 photometric redshifts (Duncan+, 2021)
J/A+A/648/A9 : Lockman Hole Apertif map at 1.4GHz (Morganti+, 2021)
https://lofar-surveys.org/releases.html : LOFAR Home Page
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- SourceId Source identification number (Source_id)
7- 11 I5 --- IslId Island identification number (Isl_id)
13- 31 F19.15 deg RAdeg Right ascension of radio source (J2000)
(RA)
33- 50 F18.16 deg e_RAdeg rms uncertainty on RAdeg (E_RA)
52- 70 F19.15 deg DEdeg Declination of radio source (J2000) (DEC)
72- 89 F18.16 deg e_DEdeg rms uncertainty on DEdeg (E_DEC)
91-102 E12.6 Jy TotalFlux The total, integrated Stokes I flux
density of the source at the reference
frequency (Total_flux)
104-115 E12.6 Jy e_TotalFlux The 1-sigma on the total flux density of
the source (ETotalflux)
117-128 E12.6 Jy/beam PeakFlux The peak Stokes I flux density per beam
of the source (Peak_flux)
130-141 E12.6 Jy/beam e_PeakFlux The 1-sigma error on the peak flux
density per beam of the source
(EPeakflux)
143-161 F19.15 deg RAMdeg Maximun right ascension (J2000) (RA_max)
163-180 F18.16 deg e_RAMdeg rms uncertainty on RAMdeg (ERAmax)
182-200 F19.15 deg DEMdeg Maximun Declination (J2000) (DEC_max)
202-219 F18.16 deg e_DEMdeg rms uncertainty on DEMdeg (EDECmax)
221-230 F10.8 deg Maj The FWHM of the major axis of the
source, including convolution with
the 6-arcsec LOFAR beam (Maj)
232-241 F10.8 deg e_Maj rms uncertainty on Maj (E_Maj)
243-252 F10.8 deg Min The FWHM of the minor axis of the
source, including convolution with
the 6-arcsec LOFAR beam (Min)
254-263 F10.8 deg e_Min rms uncertainty on Min (E_Min)
265-276 F12.8 deg PA The position angle of the major
axis of the source measured east of
north, including convolution with
the 6-arcsec LOFAR beam (PA)
278-289 F12.8 deg e_PA rms uncertainty on PA (E_PA)
291-300 F10.8 deg MajIp The FWHM of the major axis of the
image plane (Majimgplane)
302-311 F10.8 deg e_MajIp rms uncertainty on MajIp (EMajimg_plane)
313-322 F10.8 deg MinIp The FWHM of the minor axis of the
image plane (Minimgplane)
324-333 F10.8 deg e_MinIp rms uncertainty on MinIp (EMinimg_plane)
335-346 F12.8 deg PAIp The position angle of the major axis of
the image plane (PAimgplane)
348-359 F12.8 deg e_PAIp rms uncertainty on PAIp (EPAimg_plane)
361-370 F10.8 deg DCMaj The FWHM of the major axis of the
source, after de-convolution with
the 6-arcsec LOFAR beam (DC_Maj)
372-381 F10.8 deg e_DCMaj rms uncertainty on DCMaj (EDCMaj)
383-392 F10.8 deg DCMin The FWHM of the minor axis of the
source, after de-convolution with
the 6-arcsec LOFAR beam (DC_Min)
394-403 F10.8 deg e_DCMin rms uncertainty on DCMin (EDCMin)
405-416 F12.8 deg DCPA The position angle of the major
axis of the source measured east of
north, after de-convolution with
the 6-arcsec (DC_PA)
418-429 F12.8 deg e_DCPA rms uncertainty on DCPA (EDCPA)
431-440 F10.8 deg DCMajIp The FWHM of the major axis of the image
plane, after de-convolution
(DCMajimg_plane)
442-451 F10.8 deg e_DCMajIp rms uncertainty on DCMajIp
(EDCMajimgplane)
453-462 F10.8 deg DCMinIp The FWHM of the minor axis of the image
plane, after de-convolution
(DCMinimg_plane)
464-473 F10.8 deg e_DCMinIp rms uncertainty on DCMinIp
(EDCMinimgplane)
475-486 F12.8 deg DCPAIp The position angle of the major
axis of the image plane,
after de-convolution (DCPAimg_plane)
488-499 F12.8 deg e_DCPAIp rms uncertainty on DCPAIp
(EDCPAimgplane)
501-512 E12.6 Jy FtotIsl Island total flux (IslTotalflux)
514-525 E12.6 Jy e_FtotIsl rms uncertainty on FtotIsl
(EIslTotal_flux)
527-538 E12.6 Jy/beam rmsIsl Island rms (Isl_rms)
540-551 E12.6 Jy/beam meanIsl [0] Island mean (Isl_mean)
553-564 E12.6 Jy/beam rmsIslRes Island rms residual (ResidIslrms)
566-577 E12.6 Jy/beam meanIslRes Island mean residual (ResidIslmean)
579 A1 --- SCode [SMC] A code that defines the source
structure (S_Code) (1)
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Note (1): Source structure code as follows:
S = for single Gaussian
M = for multiple Gaussian
C = single-Gaussian source in an island with other sources
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Acknowledgements:
Jose Sabater Montes, jsm(at)roe.ac.uk
References:
Tasse et al., Paper I 2020A&A...248A...1T 2020A&A...248A...1T
Kondapally et al., Paper III 2020A&A...248A...3S 2020A&A...248A...3S, Cat. J/A+A/648/A3
Duncan et al., Paper IV 2020A&A...248A...4D 2020A&A...248A...4D, Cat. J/A+A/648/A4
Mandal et al., Paper V 2020A&A...248A...5M 2020A&A...248A...5M
Smith et al., Paper VI 2020A&A...248A...6S 2020A&A...248A...6S
Gloudemans et al., Paper VII 2020A&A...248A...7G 2020A&A...248A...7G
Wang et al., Paper VIII 2020A&A...248A...8W 2020A&A...248A...8W
Morganti et al., Paper IX 2020A&A...248A...9M 2020A&A...248A...9M, Cat. J/A+A/648/A9
Hardcastle et al., Paper X 2020A&A...248A..10H 2020A&A...248A..10H
Osinga et al., Paper XI 2020A&A...248A..11O 2020A&A...248A..11O
Herrera Ruiz et al., Paper XII 2020A&A...248A..12H 2020A&A...248A..12H
Callingham et al., Paper XIII 2020A&A...248A..13C 2020A&A...248A..13C
(End) Patricia Vannier [CDS] 29-Jan-2021