J/AJ/121/1872 FIRST radio-selected QSOs (Helfand+, 2001)
Long-term optical variability of radio-selected quasars from the FIRST survey.
Helfand D.J., Stone R.P.S., Willman B., White R.L., Becker R.H., Price T.,
Gregg M.D., McMahon R.G.
<Astron. J. 121, 1872 (2001)>
=2001AJ....121.1872H 2001AJ....121.1872H
ADC_Keywords: QSOs ; Photometry ; Redshifts
Keywords: methods: statistical - quasars: general - surveys
Abstract:
We have obtained single-epoch optical photometry for 202 quasars,
taken from the FIRST Bright Quasar Survey (FBQS), which span a wide
range in radio loudness. Comparison with the magnitudes of these
objects on the POSS-I plates provides by far the largest sample of
long-term variability amplitudes for radio-selected quasars yet
produced. We find the quasars to be more variable in the blue than in
the red band, consistent with work on optically selected samples. The
previously noted trend of decreasing variability with increasing
optical luminosity applies only to radio-quiet objects. Furthermore,
we do not confirm a rise in variability amplitude with redshift, nor
do we see any dependence on radio flux or luminosity. The variability
over a radio-optical flux ratio range spanning a factor of 60000 from
radio-quiet to extreme radio-loud objects is largely constant,
although there is a suggestion of greater variability in the extreme
radio-loud objects. We demonstrate the importance of Malmquist bias in
variability studies and develop a procedure to correct for the bias in
order to reveal the underlying variability properties of the sample.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 134 201 FIRST Variable Quasar Catalog
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See also:
IX/15 : Einstein EMSS Survey (Gioia+ 1990, Stocke+ 1991)
VIII/59 : the FIRST Survey, version 1999Jul (White+ 1999)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh FIRST radio Right Ascension (J2000)
4- 5 I2 min RAm FIRST radio Right Ascension (J2000)
7- 11 F5.2 s RAs FIRST radio Right Ascension (J2000)
13 A1 --- DE- Sign of the Declination (J2000)
14- 15 I2 deg DEd FIRST radio Declination (J2000)
17- 18 I2 arcmin DEm FIRST radio Declination (J2000)
20- 23 F4.1 arcsec DEs FIRST radio Declination (J2000)
25- 32 F8.3 yr Obs1 Year of POSS-I observation
34- 41 F8.3 yr Obs2 Year of CCD observation
43 A1 --- f_Bmag [*] Indicates a source with too few CCD
calibration stars to recalibrate the POSS-I
magnitudes
45- 49 F5.2 mag Bmag Extinction-corrected B band magnitude
51- 55 F5.2 mag Omag Extinction-corrected POSS-I O band magnitude
57- 61 F5.2 mag B-O The (B-O) color
63- 67 F5.2 mag Rmag Extinction-corrected R band magnitude
69- 73 F5.2 mag Emag Extinction-corrected POSS-I E band magnitude
75- 79 F5.2 mag R-E The (R-E) color
81- 88 F8.2 mJy P20cm The peak 20cm (1.5GHz) flux density
90- 97 F8.2 mJy I20cm The integrated 20cm (1.5GHz) flux density
99-103 F5.3 --- z Redshift
105-109 F5.1 mag BMag The absolute B band magnitude
111-114 F4.1 [mW/m2/Hz] logLum Log of the radio luminosity in
erg/cm2/s/Hz (1)
116-120 F5.2 --- logR Log of the K-corrected 5GHz radio to
2500Å optical luminosity (2)
122-133 A12 --- Morph Radio morphology (3)
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Note (1): At a rest-frame frequency of 5 GHz, assuming spectral index
α=-0.5(Fν ∝ να).
Note (2): Using the definition of Stocke et al. (1991, Cat. IX/15).
Note (3): Categories are FRII (double, with approximate separation in
arcseconds), core-jet (with approximate core-jet length in
arcseconds), and complex. Objects with no notation are symmetrical,
isolated sources.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 08-Jun-2001