J/MNRAS/268/305 Variability of optically selected quasars (Hook+ 1994)
The variability of optically selected quasars
Hook I.M., McMahon R.G., Boyle B.J., Irwin M.J.
<Mon. Not. R. Astron. Soc. 268, 305 (1994)>
=1994MNRAS.268..305H 1994MNRAS.268..305H
ADC_Keywords: QSOs ; Redshifts ; Magnitudes
Keywords: quasars: general
Abstract:
The variability properties of a sample of ∼300 optically selected
quasars near the South Galactic Pole (SGP) have been studied over a
baseline of 16 years using a series of twelve UK Schmidt Telescope
BJ plates at seven epochs. In this sample there is a correlation
between variability and both quasar luminosity and redshift, at
greater than the 99 per cent significance level. Quasars of high
luminosity show significantly less variability than those with low
luminosity, the rms variation ranging from about 0.25mag at MB=-23
to 0.1mag at MB=-28. The observed trends can be explained by an
intrinsic dependence of quasar variability on luminosity combined with
the effects of time dilation, and have implications for quasar samples
selected by variability or multicolour techniques. The change in the
slope of the n(m) relation at the break can be less pronounced in
variability-selected samples. Our results can be used to test models
for the origin and reprocessing of the continuum emission in quasars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 47 332 Positions, redshifts, mean apparent Bj magnitudes
and variability index for the SGP sample
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See also:
J/A+A/353/77 : Luminous QSO variability & polarization (Teerikorpi+, 2000)
J/A+A/321/123 : Optical variability of QSOs (Cristiani+ 1997)
J/A+AS/143/357 : Tuorla Quasar Monitoring (Katajainen+ 2000)
J/MNRAS/260/202 : Quasar luminosity function (Hawkins+, 1993)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1 I1 h RAh Right ascension (1950.0)
3- 4 I2 min RAm Right ascension (1950.0)
6- 10 F5.2 s RAs Right ascension (1950.0)
12 A1 --- DE- Declination sign
13- 14 I2 deg DEd Declination (1950.0)
16- 17 I2 arcmin DEm Declination (1950.0)
19- 22 F4.1 arcsec DEs Declination (1950.0)
24- 27 F4.2 --- z Redshift
29- 33 F5.2 mag Bj Mean apparent BJ magnitude
35- 38 F4.2 --- sigV Variability index σV (1)
40- 41 I2 --- Ref Reference (2)
43- 47 A5 --- Note Notes (3)
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Note (1): σv=1/(Ne-1)*[∑(i=1 to Ne)(|mi-|)]*sqr(π/2) where
Ne is the number of epochs at which the quasar was visible on the
plate and mi the magnitude of the quasar at the epoch i
Note (2): References are numbered as follows::
1 = Boyle et al., 1985MNRAS.216..623B 1985MNRAS.216..623B
2 = Boyle et al., 1990, Cat. J/MNRAS/243/1
3 = Burbidge et al., 1977ApJ...218....1B 1977ApJ...218....1B
4 = Campusano, 1986IAUS..119...49C 1986IAUS..119...49C
5 = Campusano, 1991AJ....102..502C 1991AJ....102..502C
6 = Hazard et al., 1986Natur.322...38H 1986Natur.322...38H
7 = Hazard et al., 1986MNRAS.223...87H 1986MNRAS.223...87H
8 = Hazard et al., 1987ApJ...323..263H 1987ApJ...323..263H
9 = Hazard & McMahon, in prep.
10 = Jauncey et al., 1984ApJ...286..498J 1984ApJ...286..498J
11 = Morris et al., 1991AJ....102.1627M 1991AJ....102.1627M
12 = Pocok et al., 1984MNRAS.210..373P 1984MNRAS.210..373P
13 = Savage et al., 1985MNRAS.213..485S 1985MNRAS.213..485S
14 = Smith et al., 1981MNRAS.195..437S 1981MNRAS.195..437S
15 = Trew et al., 1982MNRAS.200..785T 1982MNRAS.200..785T
16 = Wampler, 1985ApJ...296..416W 1985ApJ...296..416W
17 = Warren et al., 1987Natur.330..453W 1987Natur.330..453W
18 = Warren et al., 1987Natur.325..131W 1987Natur.325..131W
19 = Warren et al., 1991, Cat. J/ApJS/76/23
Note (3): the symbols mean the following:
a = z < 0.3
b = > 21.0
c = <MB> > -23.0
d = classified as non-stellar by APM
e = merged with another image on reference plate
f = object appeared at fewer than 5 independent epochs
g = photometry on plate J14545 affected by fireball
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History: Prepared via OCR at CDS.
* Corrections made on 21-Jul-1997:
In line 297: "1 1 11.81" corrected in "1 1 01.81"
In line 298: "1 1 14.08" corrected in "1 1 04.08"
In line 299: "1 1 18.24" corrected in "1 1 08.24"
In line 303: "1 1 20.67" corrected in "1 2 00.67"
In line 304: "1 1 23.81" corrected in "1 2 03.81"
(End) James Marcout, Patricia Bauer [CDS] 07-Mar-1997