VIII/74A SPECFIND Catalog of radio continuum spectra (Vollmer+ 2005)
A method for determining radio continuum spectra, and its application
to large surveys
Vollmer B., Davoust E., Dubois P., Genova F., Ochsenbein F., van Driel W.
<Astron. Astrophys. 431, 1177 (2005)>
=2005A&A...431.1177V 2005A&A...431.1177V
ADC_Keywords: Radio sources ; Galaxies, radio ; Radio continuum
Keywords: astronomical data bases: miscellaneous - radio continuum: general
Description:
SPECFIND is a new tool to extract cross-identifications and radio
continuum spectra from radio catalogues contained in the VIZIER
database of the CDS. It is designed to handle radio surveys of very
different resolutions and sensitivities. Power laws are fitted to the
radio spectra, resulting in the determination of a power law slope
and a zero-point. SPECFIND has been applied to 22 survey catalogues at
11 different frequencies (159 - 8400 MHz) containing a total of 3.5
million sources, leading to 757894 independent radio
cross-identifications and 66866 independent radio spectra with more
than two independent frequencies. The code was tested and its results
validated by a comparison between the spectral indices found by
SPECFIND and those determined by other authors. The determined
spectral indices have an error of about ±0.3. Negative spectral
indices have smaller errors, while the error of positive spectral
indices can be larger, mainly because of the occurrence of a peak in
the spectrum. The code is quite rapid (less than 3 hr running time on
a standard PC for 3.5 million sources) and since it is written in C,
it can be run on virtually all PCs with at least 512∼MB RAM. It
produces an output of variable format that can be adapted easily to
the purpose of the user.
The results of the spectrum identification process are provided as a
master table, where a spectrum is attached to each radio source. Due
to the SPECFIND algorithm, different radio components of the same
physical source can have somewhat different slopes and zero-points.
The SPECFIND subdirectory contains the code (in C) and the data used
to generate the catalogue, as well as a user manual (manual.ps). For
compilation please IMPERATIVELY read the README file stored in the
SPECFIND subdirectory.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
spectra.dat 114 375105 The parameters of the radio spectra
SPECFIND/* . 24 Sub-directory containing SPECFIND code & catalogs
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See also:
VIII/13 : A new catalog of 53522 4.85GHz sources (BWE) (Becker+ 1991)
VIII/14 : 87GB Catalog of radio sources (Gregory et al., 1991)
VIII/15 : Parkes Radio Sources Catalogue (PKS) (Wright+ 1990)
VIII/16 : Molonglo Reference Catalogue of Radio Sources (MRC) (Large+ 1991)
VIII/17 : The North 20cm Survey (WB) (White+ 1992)
VIII/36 : The Second Bologna Survey (B2) (Colla+ 1970-1974)
VIII/37 : The Third Bologna Survey (B3) (Ficarra+ 1985)
VIII/38 : The Parkes-MIT-NRAO 4.85GHz (PMN) Surveys (Griffith+ 1993-1996)
VIII/40 : GB6 catalog of radio sources (Gregory+ 1996)
VIII/42 : Texas Survey of radio sources at 365MHz (TXS) (Douglas+ 1996)
VIII/44 : Miyun 232MHz survey (MIYUN) (Zhang+ 1997)
VIII/52 : The MIT-Green Bank 5GHz Survey (Bennett+, 1986-91)
VIII/60 : Interferometer phase calibration sources (JVAS) (Patnaik+ 1998)
VIII/62 : The Westerbork Northern Sky Survey (WENSS) (Leiden, 1998)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VIII/69 : The WISH catalogue at 352 MHz (de Breuck+ 2002)
VIII/70 : Sydney University Molonglo Sky Survey (SUMSS) (Mauch+ 2003)
VIII/71 : The FIRST Survey Catalog, Version 03Apr11 (Becker+ 2003)
J/A+AS/85/805 : 11cm radio continuum survey. IV. (F3R) (Fuerst+ 1990)
Byte-by-byte Description of file: spectra.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Seq [1,66985] Sequential number of the spectrum (1)
8- 29 A22 --- Name Main name of the radio source (2)
31- 32 I2 --- N Number of points in spectrum
34- 38 F5.2 --- a Slope of spectrum (3)
40- 44 F5.2 [mJy] b Abscissa of spectrum (3)
47- 50 I4 MHz nu Frequency
52- 60 E9.3 mJy S(nu) Flux density at frequency nu
62- 69 E8.2 mJy e_S(nu) Mean error on S(nu)
71- 78 F8.4 deg RAdeg Right ascension (J2000) of source
80- 87 F8.4 deg DEdeg Declination (J2000) of source
90- 98 E9.3 mJy dFlux Difference with flux expected from NVSS
101-106 F6.1 arcsec dRA Offset in RA from NVSS source
109-114 F6.1 arcsec dDE Offset in DE from NVSS source
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Note (1): This number relates the sources that contribute to a single
spectrum, i.e. there are N radio sources sharing the same Seq number.
The number of independent spectra is 66985.
Note (2): a summary of the names, with indication of interferometric
or single dish instrumentation, frequency, resolution, sensitivity
limit (mJy), number of sources, percentage of sources with identified
spectrum, and the identification of the catalog in the CDS collection.
--------------------------------------------------------------
Catal. I/S MHz arcmin Smin Nsrc %sp CatalogID
--------------------------------------------------------------
JVAS I 8400 0.0055 30 2246 72 VIII/60
GB6 S 4850 3.5 18 75162 59 VIII/40
87GB S 4850 3.5 25 54579 64 VIII/14
BWE S 4850 3.5 25 53522 61 VIII/13
PMN S 4850 3.5 20 50814 30 VIII/38
MITG S 4850 2.8 40 24180 52 VIII/52
PKS S 2700 8.0 50 8264 65 VIII/15
F3R S 2700 4.3 40 6495 61 J/A+AS/85/805
FIRST I 1400 0.0833 1 811117 1.5 VIII/71
NVSS I 1400 0.75 2 1773484 3.6 VIII/65
WB S 1400 10. 100 31524 60 VIII/17
SUMSS I 843 0.75 8 134870 1.8 VIII/70
B2 I 408 8.0 250 9929 72 VIII/36
B3 I 408 5.0 100 13340 66 VIII/37
MRC I 408 3.0 700 12141 73 VIII/16
TXS I 365 0.1 250 66841 57 VIII/42
WISH I 325 0.9 10 90357 8.4 VIII/69
WENSS I 325 0.9 18 229420 17 VIII/62
MIYUN I 232 3.8 100 34426 40 VIII/44
4C I 178 11.5 2000 4844 53 VIII/4
3CR I 178 6.0 5000 327 31 VIII/1
3C I 159 10.0 7000 470 3.4 VIII/1
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Note (3): The coefficients of a and b of the flux density parametrization
log(S(ν)) = a.log(ν) + b
where the log is decimal (log10), S expressed in mJy and ν in
MHz. Thus b represents log(S(1MHz)/1mJy).
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History:
* 01-Sep-2004: First version, with 374361 spectra
* 25-Apr-2005: Version 'A', containing 375105 spectra
Thanks to R. Hunstead, we became aware of two erroneous columns in
the MRC and 4C SPECFIND input catalogues where the values for the
arcseconds in Declination were lost or erroneous. These errors are
corrected in the new version of the catalogue. Due to these new
coordinates the number of rows has increased to 375105.
* 29-Nov-2006: Some 'MY' names had their declination part in error,
and were fixed.
(End) Bernd Vollmer, Francois Ochsenbein [CDS] 25-Apr-2005