J/ApJ/818/105 CNSS pilot survey (Mooley+, 2016)
The Caltech-NRAO stripe 82 survey (CNSS). I. The pilot radio transient survey
in 50 deg2.
Mooley K.P., Hallinan G., Bourke S., Horesh A., Myers S.T., Frail D.A.,
Kulkarni S.R., Levitan D.B., Kasliwal M.M., Cenko S.B., Cao Y., Bellm E.,
Laher R.R.
<Astrophys. J., 818, 105 (2016)>
=2016ApJ...818..105M 2016ApJ...818..105M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio - Redshifts - Galaxy catalogs
Keywords: catalogs; galaxies: active; radio continuum: galaxies;
stars: activity; supernovae: general; surveys
Abstract:
We have commenced a multiyear program, the Caltech-NRAO Stripe 82
Survey (CNSS), to search for radio transients with the Jansky VLA in
the Sloan Digital Sky Survey Stripe 82 region. The CNSS will deliver
five epochs over the entire ∼270deg2 of Stripe 82, an eventual deep
combined map with an rms noise of ∼40µJy and catalogs at a
frequency of 3 GHz, and having a spatial resolution of 3". This first
paper presents the results from an initial pilot survey of a 50deg2
region of Stripe 82, involving four epochs spanning logarithmic
timescales between 1 week and 1.5yr, with the combined map having a
median rms noise of 35µJy. This pilot survey enabled the
development of the hardware and software for rapid data processing, as
well as transient detection and follow-up, necessary for the full
270deg2 survey. Data editing, calibration, imaging, source
extraction, cataloging, and transient identification were completed in
a semi-automated fashion within 6 hr of completion of each epoch of
observations, using dedicated computational hardware at the NRAO in
Socorro and custom-developed data reduction and transient detection
pipelines. Classification of variable and transient sources relied
heavily on the wealth of multiwavelength legacy survey data in the
Stripe 82 region, supplemented by repeated mapping of the region by
the Palomar Transient Factory. A total of 3.9-0.9+0.5% of the few
thousand detected point sources were found to vary by greater than
30%, consistent with similar studies at 1.4 and 5 GHz. Multiwavelength
photometric data and light curves suggest that the variability is
mostly due to shock-induced flaring in the jets of active galactic
nuclei (AGNs). Although this was only a pilot survey, we detected two
bona fide transients, associated with an RS CVn binary and a dKe star.
Comparison with existing legacy survey data (FIRST, VLA-Stripe 82)
revealed additional highly variable and transient sources on
timescales between 5 and 20yr, largely associated with renewed AGN
activity. The rates of such AGNs possibly imply episodes of enhanced
accretion and jet activity occurring once every ∼40,000yr in these
galaxies. We compile the revised radio transient rates and make
recommendations for future transient surveys and joint radio-optical
experiments.
Description:
The radio observations were carried out across four epochs (E1-E4)
with the Jansky VLA in B array configuration, and S band was chosen to
maximize survey speed. The optical survey, designed to be
contemporaneous with the radio survey, was carried out with the 1.2-m
(48-inch) Samuel Oschin Telescope at the Palomar Observatory as part
of the Palomar Transient Factory (PTF).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 170 152 Summary of the radio transient and variable
sources found in this work
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See also:
B/wds : Washington Visual Double Star Catalog (Mason+ 2001-2014)
IX/10A : ROSAT All-Sky Bright Source Catalog (1RXS) (Voges+ 1999)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
II/294 : SDSS Photometric Catalog, DR7 (Adelman- McCarthy+, 2009)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VIII/59 : The FIRST Survey, version 1999Jul (White+ 1999)
VIII/87 : Allen Tel. Array 20cm Survey (ATATS). I. (Croft+ 2010)
J/A+AS/132/305 : Extragal. radio sources at 22, 37 and 87GHz
(Terasranta+ 1998)
J/ApJS/143/1 : FIRST-APM Source Catalog (McMahon+, 2002)
J/AJ/127/2565 : Faint FIRST variable radio sources (De Vries+, 2004)
J/AJ/130/1373 : Radio observations of the HDFS region. II (Huynh+, 2005)
J/AJ/135/2470 : Radio observations of the HDFS region. IV (Huynh+, 2008)
J/ApJ/689/108 : MASIV survey. II. First four epochs (Lovell+, 2008)
J/ApJ/696/870 : Catalina Real-time Transient Survey CRTS (Drake+, 2009)
J/ApJ/740/65 : VLA search for 5GHz radio transients (Ofek+, 2011)
J/ApJS/194/29 : Observations of blazars at 15GHz (Richards+, 2011)
J/ApJ/742/49 : Variable and transient radio sources in FIRST
(Thyagarajan+, 2011)
J/ApJS/203/15 : Counterparts to 1.4GHz ECDF-S sources (Bonzini+, 2012)
J/ApJ/746/156 : Radio afterglow observations of GRBs (Chandra+, 2012)
J/MNRAS/421/1644 : 843MHz MOST ATLAS catalogue (Randall+, 2012)
J/A+A/553/A107 : Variability of 198 extragal. radio sources (Chen+, 2013)
J/ApJ/769/125 : 1.4GHz radio variability in FIRST & SDSS Stripe 82
(Hodge+, 2013)
J/MNRAS/453/4020 : ATLAS 1.4GHz Data Release 3 (Franzen+, 2015)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Time Timescale of search (less than 1 week, 1 month,
1.5yr, 20yr)
20- 32 A13 --- VTC VTC name (VTC JHHMMSS+DDMMSS in SIMBAD)
34- 43 F10.6 deg RAdeg [329.252/353.256] Right ascension (J2000)
45- 53 F9.6 deg DEdeg [-1.193/1.197] Declination (J2000)
55- 61 F7.3 mJy SE1 [0.09/359.852] Flux density at epoch E1
63- 67 F5.3 mJy e_SE1 [0.054/1.2] Error in SE1
69- 75 F7.3 mJy SE2 [0.271/324.569] Flux density at epoch E2
77- 81 F5.3 mJy e_SE2 [0.044/0.769] Error in SE2
83- 89 F7.3 mJy SE3 [0.046/362.536] Flux density at epoch E3
91- 95 F5.3 mJy e_SE3 [0.047/1.024] Error in SE3
97-103 F7.3 mJy SE4 [0.098/545.119] Flux density at epoch E4
105-109 F5.3 mJy e_SE4 [0.041/0.403] Error in SE4
111-115 F5.2 --- m [-0.81/1.61] Modulation index
117 A1 --- l_Sf [<] Limit flag on Sf (1)
119-124 F6.2 mJy Sf [0.49/617.48] FIRST flux density
126-129 F4.2 mJy e_Sf [0.09/0.89]? Error in Sf
131 A1 --- l_Sh [<] Limit flag on Sh (1)
133-138 F6.2 mJy Sh [0.17/397.62]? Hodge et al. (2011, Cat.
J/AJ/142/3) flux density
140-143 F4.2 mJy e_Sh [0.05/5.57]? Error in Sh
145-148 F4.1 mag rmag [8.9/25.3]? SDSS r magnitude
150-151 A2 --- PTF [nv/V ] Variability of optical counterpart (2)
153-156 F4.2 --- zsp [0.06/2.99]? Spectroscopic redshift (3)
158 A1 --- n_zsp [a] Photometric redshift estimate from SDSS
160-163 F4.1 10-3W/m2 Lum [29.1/34.7]? Radio luminosity (4)
165-170 A6 --- Id Identification (AGN QSO)
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Note (1): All flux density upper limits are 3σ.
Note (2): Variability properties of the optical counterparts of the radio
variable sources, defined as follows:
V = variable
nv = not variable
Note (3): Spectroscopic redshift from SDSS or from our follow-up observations.
Note (4): Radio luminosity averaged over the four epochs of the pilot survey.
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History:
From electronic version of the journal
(End) Marianne Brouty [CDS] 10-Nov-2017