J/ApJ/762/93 PiGSS. III. ELAIS-N1, Coma & Lockman fields (Croft+, 2013)
The Allen Telescope Array Pi GHz Sky Survey.
III. The ELAIS-N1, Coma, and Lockman Hole fields.
Croft S., Bower G.C., Whysong D.
<Astrophys. J., 762, 93 (2013)>
=2013ApJ...762...93C 2013ApJ...762...93C
ADC_Keywords: Radio continuum ; Surveys
Keywords: catalogs; methods: data analysis; radio continuum: galaxies
radio continuum: general; surveys
Abstract:
We present results from a total of 459 repeated 3.1GHz radio continuum
observations (of which 379 were used in a search for transient
sources) of the ELAIS-N1, Coma, Lockman Hole, and NOAO Deep Wide Field
Survey fields as part of the Pi GHz Sky Survey. The observations were
taken approximately once per day between 2009 May and 2011 April. Each
image covers 11.8 square degrees and has 100" FWHM resolution. Deep
images for each of the four fields have rms noise between 180 and
310µJy, and the corresponding catalogs contain ∼200 sources in each
field. Typically 40-50 of these sources are detected in each
single-epoch image. This represents one of the shortest cadence,
largest area, multi-epoch surveys undertaken at these frequencies. We
compare the catalogs generated from the combined images to those from
individual epochs, and from monthly averages, as well as to legacy
surveys. We undertake a search for transients, with particular
emphasis on excluding false positive sources. We find no confirmed
transients, defined here as sources that can be shown to have varied
by at least a factor of 10. However, we find one source that
brightened in a single-epoch image to at least six times the upper
limit from the corresponding deep image. We also find a source
associated with a z=0.6 quasar which appears to have brightened by a
factor ∼3 in one of our deep images, when compared to catalogs from
legacy surveys. We place new upper limits on the number of transients
brighter than 10mJy: fewer than 0.08 transients deg-2 with
characteristic timescales of months to years; fewer than 0.02deg-2
with timescales of months; and fewer than 0.009deg-2 with timescales
of days. We also plot upper limits as a function of flux density for
transients on the same timescales.
Description:
The Allen Telescope Array (ATA), is a 42-element interferometer,
located at Hat Creek Radio Observatory in Northern California. Each
element is a 6.1m dish with a broadband feed that receives radiation
from 0.5 to 11GHz.
Bower et al. (2010, Cat. J/ApJ/725/1792; Paper I) introduced a large
ATA survey, the Pi GHz Sky Survey (PiGSS). PiGSS covered ∼2500 square
degrees in two epochs, and an additional ∼2500 square degrees in a
single epoch, in two simultaneous 100 MHz bands centered at 3.04 and
3.14 GHz (S. Croft et al., in preparation). As well as the large
field, PiGSS also incorporates four smaller (∼12 square degree) fields
observed with a cadence of days. Paper I presents results from a deep
image made from 75 epochs of observation of one of these fields
(centered on the location of the NOAO Deep Wide Field Survey, NDWFS).
Bower et al. (2011, Cat. J/ApJ/739/76; Paper II), compares catalogs
generated from the individual epochs of this field (and monthly
averages of them) to each other, and to other radio, infrared and
X-ray catalogs.
In this paper, we present results from the other three 12 square
degree deep fields, centered on the ELAIS-N1, Lockman Hole, and Coma
fields, as well as a partial reanalysis of the NDWFS results from
Paper II.
---------------------------------------------------------------------------
Field RA DE Date Range Total number Deep Field
(J2000) of Epochs rms (uJy)
---------------------------------------------------------------------------
NDWFS 14 32 00 +34 16 00 2009/05/20-2009/09/29 96 250
Lockman 10 52 00 +57 38 00 2009/02/02-2010/07/07 132 250
ELAIS-N1 16 12 42 +53 48 31 2010/05/30-2011/01/20 179 180
Coma 13 00 43 +27 11 13 2011/01/24-2011/04/07 52 310
---------------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 112 238 ELAIS N1 catalog
table3.dat 112 189 Lockman catalog
table4.dat 112 186 Coma catalog
table5.dat 112 195 NDWFS (NOAO Deep Wide Field Survey) updated catalog
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See also:
VIII/87 : The Allen Telescope Array 20cm Survey (ATATS). I. (Croft+ 2010)
VIII/40 : GB6 catalog of radio sources (Gregory+ 1996)
J/ApJ/742/49 : FIRST variable & transient radio sources (Thyagarajan+, 2011)
J/ApJ/740/65 : VLA search for 5GHz radio transients (Ofek+, 2011)
J/ApJ/739/76 : Pi GHz Sky Survey (PiGSS). II. (Bower+, 2011)
J/ApJ/725/1792 : Pi Ghz Sky Survey (PiGSS). I. (Bower+, 2010)
J/ApJ/714/1689 : DRAO ELAIS N1 catalog (Grant+, 2010)
J/AJ/137/4846 : 90cm observations of the deep SWIRE field (Owen+, 2009)
J/AJ/137/4436 : Coma cluster VLA survey (Miller+, 2009)
J/MNRAS/397/281 : Radio imaging in Lockman Hole (Ibar+, 2009)
J/MNRAS/395/269 : ELAIS-N1 field 325MHz observations (Sirothia+, 2009)
J/ApJ/689/108 : MASIV survey. II. First four epochs (Lovell+, 2008)
J/MNRAS/387/1037 : 610-MHz survey of Lockman Hole with GMRT (Garn+, 2008)
J/ApJS/161/9 : X-ray survey of the NDWFS Bootes field (Kenter+, 2005)
J/AJ/123/1784 : 1.4 GHz imaging of the Bootes field (de Vries+, 2002)
Byte-by-byte Description of file: table[2345].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- PiGSS PiGSS identification (JHHMMSS+DDMMSS) (1)
16- 23 F8.5 h RAh Decimal hour of Right Ascension (J2000)
25- 32 F8.5 deg DEdeg Decimal degree of Declination (J2000)
34- 38 F5.1 arcsec amaj [100/331] Source major axis (2)
40- 44 F5.1 arcsec bmin [100/163] Source minor axis (2)
46- 50 F5.1 deg bPA [0/180] Source position angle (2)
52- 58 F7.2 mJy S3.04 [0.9/1599] Deep image 3.04GHz flux density (3)
60- 63 F4.2 mJy e_S3.04 [0.2/9] Uncertainty in S3040 (4)
65- 71 F7.2 mJy S3.14 Deep image 3.14GHz flux density (3)
73- 77 F5.2 mJy e_S3.14 [0.2/23] Uncertainty in S3.14 (4)
79- 81 I3 --- o_S3.04 [0/166] Number of single-epoch S3.04 images (5)
83- 85 I3 --- o_S3.14 [0/168] Number of single-epoch S3.14 images (5)
87- 89 I3 --- Ni [0/111] Number of single-epoch images at
both frequencies (5)
91- 95 F5.2 --- chi3.04 [0/26]? Reduced χ2 at 3.04GHz (6)
97-102 F6.2 --- chi3.14 [0/233]? Reduced χ2 at 3.14GHz (6)
104-107 F4.2 --- sig3.04 [0.03/0.5]? Standard deviation at 3.04GHz (7)
109-112 F4.2 --- sig3.14 [0.03/0.5]? Standard deviation at 3.14GHz (7)
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Note (1): For NDWS, UPDATED FROM ORIGINAL TABLE: Originally JHHMMSS+DDMMSS.
Note (2): For NDWS, UPDATED FROM ORIGINAL TABLE: Originally mislabeled as beam
axes and position angle.
Note (3): Made from all good data.
Note (4): Quoted uncertainties are the sum in quadrature of the uncertainties
on the fit and on the background measurement as reported by SFIND.
Note (5): With completeness better than 50mJy in which this source was
detected. Number of well-behaved epochs (PIC gain within ±0.1
of the median value; Section 3.4) with completeness better than
50mJy in which the source was simultaneously detected in each of
the single-frequency images.
Note (6): For the hypothesis of no variability, computed using only
well-behaved epochs where the source is detected at both frequencies
in 5 or more epochs.
Note (7): Divided by the mean of the single-epoch flux densities, computed
using only well-behaved epochs where the source is detected at both
frequencies in 5 or more epochs.
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History:
From electronic version of the journal
References:
Bower et al. Paper I. 2010ApJ...725.1792B 2010ApJ...725.1792B Cat. J/ApJ/725/1792
Bower et al. Paper II. 2011ApJ...739...76B 2011ApJ...739...76B Cat. J/ApJ/739/76
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 15-Sep-2014