J/ApJS/224/18 Identify giant radio sources from the NVSS (Proctor, 2016)
A selection of giant radio sources from NVSS.
Proctor D.D.
<Astrophys. J. Suppl. Ser., 224, 18-18 (2016)>
=2016ApJS..224...18P 2016ApJS..224...18P (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Active gal. nuclei
Keywords: astronomical databases: miscellaneous; catalogs; galaxies: general
Abstract:
Results of the application of pattern-recognition techniques to the
problem of identifying giant radio sources (GRSs) from the data in the
NVSS catalog are presented, and issues affecting the process are
explored. Decision-tree pattern-recognition software was applied to
training-set source pairs developed from known NVSS large-angular-size
radio galaxies. The full training set consisted of 51195 source pairs,
48 of which were known GRSs for which each lobe was primarily
represented by a single catalog component. The source pairs had a
maximum separation of 20' and a minimum component area of
1.87arcmin2 at the 1.4mJy level. The importance of comparing the
resulting probability distributions of the training and application
sets for cases of unknown class ratio is demonstrated. The probability
of correctly ranking a randomly selected (GRS, non-GRS) pair from the
best of the tested classifiers was determined to be 97.8±1.5%. The
best classifiers were applied to the over 870000 candidate pairs from
the entire catalog. Images of higher-ranked sources were visually
screened, and a table of over 1600 candidates, including morphological
annotation, is presented. These systems include doubles and triples,
wide-angle tail and narrow-angle tail, S- or Z-shaped systems, and
core-jets and resolved cores. While some resolved-lobe systems are
recovered with this technique, generally it is expected that such
systems would require a different approach.
Description:
Using the Karl G. Jansky Very Large Array (VLA), the NRAO VLA Sky
Survey (NVSS; Condon et al. 1998, VIII/65) is a 1.4GHz continuum
survey covering the entire sky north of -40° decl. with a
resolution of 45" FWHM. The associated catalog of discrete sources
from this survey contains over 1.8 million entries.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 222 1616 Giant radio sources and candidates
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See also:
VII/272 : A catalogue of Galactic supernova remnants (Green, 2014)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
J/ApJS/194/31 : Morphology for groups in the FIRST database (Proctor, 2011)
J/AJ/130/156 : Galactic radio compact HII regions at 1.4GHz (Giveon+, 2005)
J/A+A/370/409 : New sample of large angular size radio gal. I. (Lara+, 2001)
J/ApJS/126/133 : The FIRST bright quasar survey. II. (White+, 2000)
Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq Running sequence number
8- 12 A5 --- --- [NVGRC]
14- 29 A16 --- NVGRC IAU Name (JHHMMSS.s+DDMMSS) (1)
33- 34 I2 h RAh Hour of Right Ascension (J2000)
36- 37 I2 min RAm Minute of Right Ascension (J2000)
39- 43 F5.2 s RAs Second of Right Ascension (J2000)
46 A1 --- DE- Sign of the Declination (J2000)
47- 48 I2 deg DEd Degree of Declination (J2000)
50- 51 I2 arcmin DEm Arcminute of Declination (J2000)
53- 56 F4.1 arcsec DEs Arcsecond of Declination (J2000)
58 A1 --- Flag [cv] System coordinate code (2)
60- 64 F5.1 arcmin Diam [3/105] System diameter, 1.4MJy level (3)
71-184 A114 --- Notes Annotations (4)
186-222 A37 --- RID Other identifier(s) (5)
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Note (1): Coordinate based source designations are truncated, not rounded.
Note (2): It should be noted that only the coordinates associated with a NVSS
catalog entry have the significance of the NVSS entry.
GRS previously identified by Lara et al. (2001, J/A+A/370/409),
Machalski et al. (2001A&A...371..445M 2001A&A...371..445M), and
Solovyov & Verkhodanov (2014AstBu..69..141S 2014AstBu..69..141S), were retained
but not given an NVGRC designation. Coordinates are given as for
other entries.
Flag as follows:
c = system coordinate is a NVSS fitted catalog entry (557 sources);
v = coordinate is visual estimate from symmetry considerations;
Note (3): Approximately two dozen candidates less that 4.0' were retained in
the table for documentation purposes.
Note (4): Although the training set consisted of primarily FRI and FRII type
sources, FR classification was not attempted. Though many of the
larger "d" and "t" annotated systems are clearly FRII, the smaller,
less resolved sources were difficult to evaluate. It was felt such
distinctions deserved more uniform analytic attention. Also note
that other morphological types were retained for documentation
purposes. Key to annotations:
amb = ambiguous;
arc = arc or C-shape, possible edge brightened lobe, bent jets,
or ring fragment;
cj = core-jet;
d = double lobe radio galaxy - may include core-jet sources;
dd = double double morphology (DD), may be candidate DDRG;
dl = dogleg;
fishtail = multiple (usually two) lower level tails;
hymor = hybrid morphology radio source(s) (HYMORS);
int = interesting;
irr = irregular, distorted;
incidental = non-source pair systems found during cutout examinations;
jet = protrusion away from presumed core;
lobe = lobe, resolved lobe;
mg = multiple groupings possible;
nat = narrow angle tail (NAT);
point = non-extended source for which the major and minor axes appear
to be the same size;
rc = resolved compact source, non-pointlike;
ring = ring;
ring-lobe = edge or rim brightened lobe or embedded ring;
s = single source (sometimes with sidelobes) or probable chance
projection of point-like source into group;
sz = S or Z-shaped;
t = triple, no bend, little extended structure;
tail = protrusion (normally lower level) from lobe in direction
away from core;
unu = unusual, uncommon - may be due to chance projection;
w = W-shape, wiggles;
wat = wide angle tail (WAT);
x = X-shape
Note (5): Reference as below:
S14 = Solovyov & Verkhodanov 2014AstBu..69..141S 2014AstBu..69..141S
M01 = Machalski et al. 2001A&A...371..445M 2001A&A...371..445M; <[MJZ2001] JHHMM+DDMM> in Simbad.
L01 = Lara et al. 2001, J/A+A/370/409; <[LCF2001] JHHMM+DDd> in Simbad.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Jul-2016