J/ApJS/174/313 Spectra of 388 bright 74MHz sources (Helmboldt+, 2008)
Radio frequency spectra of 388 bright 74 MHz sources.
Helmboldt J.F., Kassim N.E., Cohen A.S., Lane W.M., Lazio T.J.
<Astrophys. J. Suppl. Ser., 174, 313-336 (2008)>
=2008ApJS..174..313H 2008ApJS..174..313H
ADC_Keywords: Radio sources ; Radio continuum
Keywords: catalogs - radio continuum: general - surveys
Abstract:
As a service to the community, we have compiled radio frequency
spectra from the literature for all sources within the VLA Low
Frequency Sky Survey (VLSS) that are brighter than 15Jy at 74MHz.
Over 160 references were used to maximize the amount of spectral data
used in the compilation of the spectra, while also taking care to
determine the corrections needed to put the flux densities from all
reference on the same absolute flux density scale. With the new VLSS
data, we are able to vastly improve on previous efforts to compile
spectra of bright radio sources to frequencies below 100MHz because
(1) the VLSS flux densities are more reliable than those from some
previous low-frequency surveys and (2) the VLSS covers a much larger
area of the sky (δ>-30°) than many other low-frequency
surveys (e.g., the 8C survey).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 33 5869 Fluxes
table4.dat 118 388 Parameters of the Spectral Fits
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See also:
VIII/79 : The VLA Low-frequency Sky Survey at 74MHz (Cohen+ 2007)
VIII/85 : SPECFIND V2.0 Catalog of radio continuum spectra (Vollmer+ 2009)
J/ApJS/150/417 : Deep, high-resolution survey at 74MHz (Cohen+, 2004)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name The VLSS source name (JHHMM+DDd) (G1)
11- 16 I6 MHz Freq Frequency
18- 25 F8.2 Jy S Flux density (1)
27- 33 F7.2 Jy e_S The 1σ uncertainty in S
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Note (1): All flux densities were obtained from the CATS database with the
exception of flux densities at 327, 365, 1400, and 4850MHz which were
taken from the TXS, WENSS, NVSS, and GB6 or PMN catalogs where
applicable (see text). See Table 2 for a list of the references used
in the CATS database searches.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name The VLSS source name (G1)
11- 32 A22 --- OName Other source name from NED
(some names truncated)
34 I1 --- Ng Number of Gaussian components in VLSS (1)
36- 37 I2 h RAh Hour of Right Ascension (J2000)
39- 40 I2 min RAm Minute of Right Ascension (J2000)
42- 45 F4.1 s RAs Second of Right Ascension (J2000)
47 A1 --- DE- Sign of the Declination (J2000)
48- 49 I2 deg DEd Degree of Declination (J2000)
51- 52 I2 arcmin DEm Arcminute of Declination (J2000)
54- 57 F4.1 arcsec DEs Arcsecond of Declination (J2000)
59- 60 I2 --- Nnu Number of frequencies with measured flux
densities
62- 68 F7.1 Jy S74 VLSS 74MHz flux density
70- 74 F5.2 --- alpha ? Slope of power-law fit at ν>300MHz
76- 81 F6.1 Jy S74e ? 74MHz flux density extrapolated with alpha
83- 88 F6.2 --- A ? Equation 1 "A" parameter value (2)
90- 95 F6.2 --- B ? Equation 1 "B" parameter value (2)
97-102 F6.2 --- C ? Equation 1 "C" parameter value (2)
104-110 F7.2 --- D ? Equation 1 "D" parameter value (2)
112-118 F7.3 [Jy] rms ? The rms difference between observed and
fitted flux values
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Note (1): From the VLSS image attributed to the source.
Note (2): Derived using a fit to the data for all sources with Num≥8:
log(S/1Jy) = A + B.log(ν/74MHz) + C exp(D.X)
where X = ν/74MHz.
For sources where a simple linear fit gives a quantitatively better
fit (see text), only the A and B parameters are listed.
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Global Notes:
Note (G1): this name is NOT the name recommended by the VLSS catalog
in Cohen et al. 2007AJ....134.1245C 2007AJ....134.1245C, Cat. VIII/79
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 04-Jun-2009