J/MNRAS/460/4433 SDSS Stripe 82 VLA 1-2GHz survey (Heywood+, 2016)
A deep/wide 1-2 GHz snapshot survey of SDSS Stripe 82 using the Karl G. Jansky
Very Large Array in a compact hybrid configuration.
Heywood I., Jarvis M.J., Baker A.J., Bannister K.W., Carvalho C.S.,
Hardcastle M., Hilton M., Moodley K., Smirnov O.M., Smith D.J.B.,
White S.V., Wollack E.J.
<Mon. Not. R. Astron. Soc., 460, 4433-4452 (2016)>
=2016MNRAS.460.4433H 2016MNRAS.460.4433H (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Radio sources ; Morphology
Keywords: surveys - radio continuum: general
Abstract:
We have used the Karl G. Jansky Very Large Array to image ∼100deg2
of SDSS Stripe 82 at 1-2GHz. The survey consists of 1026 snapshot
observations of 2.5-min duration, using the hybrid CnB configuration.
The survey has good sensitivity to diffuse, low surface brightness
structures and extended radio emission, making it highly synergistic
with existing 1.4GHz radio observations of the region. The principal
data products are continuum images, with 16x10 arcsec resolution, and
a catalogue containing 11782 point and Gaussian components resulting
from fits to the thresholded Stokes-I brightness distribution, forming
approximately 8948 unique radio sources. The typical effective
1σ noise level is 88µJy/beam. Spectral index estimates are
included, as derived from the 1GHz of instantaneous bandwidth.
Astrometric and photometric accuracy are in excellent agreement with
existing narrowband observations. A large-scale simulation is used to
investigate clean bias, which we extend into the spectral domain.
Clean bias remains an issue for snapshot surveys with the VLA,
affecting our total intensity measurements at the ∼1σ level.
Statistical spectral index measurements are in good agreement with
existing measurements derived from matching separate surveys at two
frequencies. At flux densities below ∼35σ the median in-band
spectral index measurements begin to exhibit a bias towards flatness
that is dependent on both flux density and the intrinsic spectral
index. In-band spectral curvature measurements are likely to be
unreliable for all but the very brightest components. Image products
and catalogues are publicly available via an FTP server
(ftp://ftp.atnf.csiro.au/pub/people/hey036/Stripe82).
Description:
The data (Project code: 13B-272) were taken with the array in the CnB
configuration. Standard wide-band mode was employed with the
correlator splitting the 1-2GHz of frequency coverage into 16
spectral windows (SPWs) with 64x1MHz channels each, and an
integration time per visibility point of 3s.
A total of 1368 target pointings were scheduled, 608 and 760 in the
eastern and western regions, respectively, coincident with the two
eastern and western areas of the existing Hodge et al. (2011, Cat.
J/AJ/142/3) data.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1e.dat 155 5674 Eastern catalogue
table1w.dat 155 6094 Western catalogue
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See also:
J/AJ/142/3 : 1.4GHz observations of Stripe 82 (Hodge+, 2011)
Byte-by-byte Description of file: table1e.dat table1w.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- ID Identifier (JHHMMSS.s+DDMMSS)
18- 26 F9.5 deg RAdeg Right ascension (J2000)
28- 35 F8.5 deg DEdeg Declination (J2000)
37- 40 F4.2 arcsec e_RAdeg 1σ uncertainty in RA
42- 45 F4.2 arcsec e_DEdeg 1σ uncertainty in DE
47- 54 F8.3 mJy Sint Integrated flux density at 1-2GHz
56- 60 F5.3 mJy e_Sint 1σ uncertainty in Sint
62- 69 F8.3 mJy/beam Speak Peak flux density at 1-2GHz
71- 75 F5.3 mJy/beam e_Speak 1σ uncertainty in Speak
77- 81 F5.1 uJy/beam rms Estimate of the local RMS noise at the
position of the component
83- 89 F7.3 --- alpha Spectral index (1)
91- 97 F7.4 arcsec Maj ?=0 Deconvolved major-axis size of the
Gaussian fitted to the component (2)
99-105 F7.4 arcsec e_Maj ?=0 1σ uncertainty in Maj
107-113 F7.4 arcsec Min ?=0 Deconvolved minor-axis size of the
Gaussian fitted to the component (2)
115-120 F6.4 arcsec e_Min ?=0 1σ uncertainty in Min
122-129 F8.4 deg PA ?=0 Position angle measured east of north of
the Gaussian fitted
131-138 F8.4 deg e_PA ?=01σ uncertainty in PA
140 I1 --- Res [0/1] flag to indicate whether or not the
component is likely to be reliably spatially
resolved, i.e. does the component lie above
the upper envelope on Fig. 13.
142-145 I4 --- IDg Zero-indexed unique identifier for the
component
147-150 I4 --- IDs Zero-indexed unique identifier for the source
152-155 I4 --- IDi Zero-indexed unique identifier for the island
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Note (1): formed from an error-weighted mean of the pixel values in the spectral
index mosaic over the extent of the component, or the extent of the survey
restoring beam, whichever is larger.
Note (2): A value of zero indicates that the source finder was unable to
determine the intrinsic size, and the component is indistinguishable from
being point-like.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Nov-2017