J/ApJS/205/13 VLA 1.4GHz survey of ECDF-S (DR2) (Miller+, 2013)
The Very Large Array 1.4 GHz survey of the Extended Chandra Deep Field South:
second data release.
Miller N.A., Bonzini M., Fomalont E.B., Kellermann K.I., Mainieri V.,
Padovani P., Rosati P., Tozzi P., Vattakunnel S.
<Astrophys. J. Suppl. Ser., 205, 13 (2013)>
=2013ApJS..205...13M 2013ApJS..205...13M
ADC_Keywords: Radio sources ; Surveys ; Morphology
Keywords: catalogs - radio continuum: galaxies - surveys
Abstract:
Deep radio observations at 1.4GHz for the Extended Chandra Deep Field
South were performed in 2007 June through September and presented in a
first data release. The survey was made using six separate pointings
of the Very Large Array with over 40hr of observation per pointing. In
the current paper, we improve on the data reduction to produce a
second data release (DR2) mosaic image. This DR2 image covers an area
of about a third of a square degree, reaches a best rms sensitivity of
6uJy, and has a typical sensitivity of 7.4uJy per 2.8" by 1.6" beam.
We also present a more comprehensive catalog, including sources down
to peak flux densities of five or more times the local rms noise along
with information on source sizes and relevant pointing data. We
discuss in some detail the consideration of whether sources are
resolved under the complication of a radio image created as a mosaic
of separate pointings each suffering some degree of bandwidth
smearing, and the accurate evaluation of the flux densities of such
sources. Finally, the radio morphologies and optical/near-IR
counterpart identifications are used to identify 17 likely
multiple-component sources and arrive at a catalog of 883 radio
sources, which is roughly double the number of sources contained in
the first data release.
Description:
In order to cover the full E-CDF-S area at near-uniform sensitivity,
we pointed the VLA at six separate coordinate locations arranged in a
hexagonal grid around the adopted center of the CDF-S, (J2000)
03:32:28.00-27:48:30.0. Our observations were spread over many days on
account of the low declination of the field and typically amounted to
5hr of time per calendar date (see the "Note (10)" below).
The images corresponding to the six individual pointings were combined
to form the final mosaic image (Figure 1).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 165 883 Main catalog of radio sources
table4.dat 165 49 Individual components of the 17 multiple-component
radio sources
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See also:
J/ApJS/179/114 : VLA 1.4GHz survey of E-CDF-S (DR1) (Miller+, 2008)
J/ApJ/698/740 : VLA survey of CDF-S. III. (Tozzi+, 2009)
J/MNRAS/420/2190 : ECDFS sources with radio counterparts (Vattakunnel+, 2012)
J/ApJS/203/15 : Counterparts to 1.4GHz sources in ECDF-S (Bonzini+, 2012)
Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/17]? Running sequence number for
multi-component source (table 4 only)
4 I1 h RAh [3] Hours of Right Ascension (J2000) (1)
6- 7 I2 min RAm [31/33] Minute of Right Ascension (J2000)
9- 13 F5.2 s RAs Second of Right Ascension (J2000)
15 A1 --- DE- [-] Sign of the Declination (J2000) (1)
16- 17 I2 deg DEd [27/28] Degree of Declination (J2000) (1)
19- 20 I2 arcmin DEm Arcminute of Declination (J2000)
22- 25 F4.1 arcsec DEs Arcsecond of Declination (J2000)
29- 34 F6.1 --- SNR [5/3055]? Signal-to-noise of peak flux density
38- 44 F7.1 uJy Sp [30/22300]? Peak flux density at 1.4GHz;
in microJy/beam
47- 50 F4.1 uJy e_Sp [6.1/12.1]? Error in Sp; microJy/beam
54- 60 F7.1 uJy Si [15.9/90450] Integrated flux density at 1.4GHz
63- 67 F5.1 uJy e_Si [6.9/168.5] Error in Si
69- 72 F4.1 arcsec Maj [1.9/18.7]? Major axis from mosaic image (2)
74- 77 F4.1 arcsec Min [0.8/9.2]? Minor axis from mosaic image (2)
80- 82 I3 deg PAmos ? Position angle from mosaic image (2)
88 I1 --- Best [1/6] Index number of pointing with lowest
RMS at source position
91- 94 F4.1 uJy RMS [9.3/15.2] RMS at source position in best n
pointing; microJy/beam
98-101 F4.1 arcsec MajLo ? Lower limit to major axis size (3)
103-106 F4.1 arcsec MajHi ? Upper limit to major axis size (3)
109-111 F3.1 arcsec MinLo ? Lower limit to minor axis size (3)
113-115 F3.1 arcsec MinHi ? Upper limit to minor axis size (3)
117-119 I3 deg PAbest ? Position angle (3)
122 I1 --- Ext? [0/1]? Flag indicating whether source was
resolved in envelope test (4)
125 A1 --- FC [IP] Prescription for recommended flux
density, Integrated ot Peak (5)
128-133 A6 --- Pnts [ 1-6] Pointings contributing to mosaic image
at source position (10)
136-139 A4 --- K08 ID of source in K08 (J/ApJS/179/71) (6)
141-145 I5 uJy Sk ? K08 source 1.4GHz flux density
147-150 I4 uJy e_Sk [8/1200]? Error in Sk
153 A1 --- l_Size Limit flag on Size (7)
154-157 F4.1 arcsec Size [0/70]? K08 1.4GHz deconvolved source size
160-162 A3 --- Rem [a-g, ] Flag(s) indicating notes on source (8)
164-165 I2 --- Fig ? Multiple component number corresponding in
table 4 (for flag "b" in table 3) or figure
number in table 4 (9)
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Note (1): In most cases, the listed position is that of the center of the
Gaussian that best fits the data. The typical position errors for
strong, unresolved sources observed with the VLA at 1.4GHz are 0.1",
and position errors attributed to the Gaussian fitting in the presence
of noise are on the order of the beam size divided by twice the S/N
(Condon 1997PASP..109..166C 1997PASP..109..166C). Thus, the position error in right
ascension for a 5σ-point source would be
(0.12+{1.6/(2x5)}2)0.5∼0.2" while the position error in
declination for the same source would be
(0.12+{2.8/(2x5)}2)0.5∼0.3".
Note (2): Includes convolution with beam.
Note (3): From best pointing, deconvolved and corrected for bandwidth smearing.
Note (4): Extended flag. If the source was found to be extended using the
"envelope" method (see Section 3.2), this column is set to 1. Sources
that were unresolved under this test have a value of 0 in this column.
Note (5): Flux density choice recommended to use: P (peak) or I (integrated).
(see Section 3.4 for further explanations).
Note (6): K08 = Kellermann et al. (2008, Cat. J/ApJS/179/71);
<[KFM2008] RID NNNA> in Simbad.
Note (7): Indicating source is unresolved and less than indicated size.
Note (8): Flag in table 3 as follows:
a = Extended source evaluated with aperture photometry and AIPS
task TVSTAT. Indicated position and peak flux density are
the maximum within the aperture, and size is based on attempt
at fitting source with single Gaussian.
b = Multiple component source. Corresponding information may be found
in Table 4 for properties of the individual fitted components, where
the number in col. "Mult" identifies the "Seq" number in that Table.
c = Pointing 5 (03:32:00.88 -27:58:57.0, J2000) used for source fit
d = Pointing 4 (03:31:33.75 -27:48:30.0, J2000) used for source fit
e = Pointing 2 (03:32:55.12 -27:38:03.0, J2000) used for source fit
f = Source has strong core plus more diffuse extended emission. The
indicated source size is that of the extended emission based on a
two-component Gaussian fit.
g = Pointing 1 (03:33:22.25 -27:48:30.0, J2000) used for source fit
Note (9): In table3, flag "b"=multiple component source. The number here
identifies the "Seq" number in table 4 where properties of the
individual fitted components are given.
In table 4, numbers reference corresponding figure number in the text.
All listed sources under a single numerical flag are considered to be
part of the single radio source, with the individual components
having been fit with Gaussians.
Note (10): the pointing IDs are:
----------------------------------------------------------------------
Pointing ID R.A. (J2000) DE. (J2000) rms sensitivity for final
image
----------------------------------------------------------------------
ECDFS 1 03:33:22.25 -27:48:30.0 10.5 muJy
ECDFS 2 03:32:55.12 -27:38:03.0 9.4 muJy
ECDFS 3 03:32:00.88 -27:38:03.0 9.7 muJy
ECDFS 4 03:31:33.75 -27:48:30.0 9.5 muJy
ECDFS 5 03:32:00.88 -27:58:57.0 10.0 muJy
ECDFS 6 03:32:55.12 -27:58:57.0 9.3 muJy
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History:
From electronic version of the journal
References:
Miller et al. Paper I. 2008ApJS..179..114M 2008ApJS..179..114M Cat. J/ApJS/179/114
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 09-Apr-2013