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J/A+A/525/A37  Variability indexes of QSOs in SDSS Stripe 82  (Meusinger+, 2011)

Spectral variability of quasars from multi-epoch photometric data in the Sloan Digital Sky Survey Stripe 82. Meusinger H., Hinze A., de Hoon A. <Astron. Astrophys. 525, A37 (2011)> =2011A&A...525A..37M
ADC_Keywords: Active gal. nuclei ; Photometry, SDSS ; QSOs Keywords: galaxies: active - quasars: general - quasars: emission lines Description: We identified 8744 quasars in the Light-Motion Curve Catalogue (LMCC; Bramich et al., 2008MNRAS.386..887B, http://das.sdss.org/value_added/stripe_82_variability/SDSS_82_public/) for the stripe 82 of the Sloan Digital Sky Survey (SDSS). The light curves were used, after correction for photometric outliers, to compute individual noise-corrected first-order structure functions (variance as a function of time-lag) binned into rest frame time-lag intervals. The mean value of the corrected structure function at rest frame time-lags from 300 to 600 days is found to be a useful variability index for the statistical investigation of quasar samples with redshifts up to ∼3. For each quasar, the variability indexes for the five SDSS bands are given along with the equatorial coordinates, redshift, mean g band magnitude, absolute i band magnitude, and a remark on spectral peculiarities. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 83 8744 Variability indexes of quasars
See also: J/ApJS/186/233 : Variable point sources in SDSS stripe 82. I. (Bhatti+, 2010) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- Seq Running number 6- 15 F10.6 deg RAdeg Right ascension in decimal degrees (J2000) 17- 25 F9.6 deg DEdeg Declination in decimal degrees (J2000) 27- 31 F5.3 --- z Redshift (spectroscopic) 33 I1 --- zFlag [0,1] Redshift Flag (0: ok, 1: uncertain) 35- 40 F6.3 mag gmag Mean apparent g band magnitude 42- 47 F6.2 mag iMAG Absolute i band magnitude (1) 49- 53 F5.3 mag+2 Vu Variability index in the u band (2) 55- 59 F5.3 mag+2 Vg Variability index in the g band (2) 61- 65 F5.3 mag+2 Vr Variability index in the r band (2) 67- 71 F5.3 mag+2 Vi Variability index in the i band (2) 73- 77 F5.3 mag+2 Vz Variability index in the z band (2) 79- 83 A5 --- Remark ? Remark about the spectrum (3)
Note (1): computed following Kennefick and Bursick (2008AJ....136.1799K) with Galactic foreground extinction from the "Galactic Dust Extinction Service" of the NASA/IPAC Infrared Science Archive. Note (2): The index is actually created to compare the variability (e.g., between different quasars with each other or between different passbands of the same quasar) but is not apt to measure the significance of the variability. On the one hand, a variability index of "0" means no significant variability. However, non-variable quasars can have also a finite (small) value but there is no critical value for such an index to clearly separate between variables and non-variables. (In the paper, we have shown that more than ∼90% of the quasars are significantly variable in the ugri bands.) Note (3): Remarks use the following abbreviations: w_l = Weak emission lines s_bal = Strong broad absorption lines x_bal = Extreme broad absorption lines myst = Mysterious spectrum
References: Bramich et al., Light-Motion Curve Catalogue, 2008MNRAS.386..887B, http://das.sdss.org/value_added/stripe_82_variability/SDSS_82_public/
(End) Helmut Meusinger [TLS, Germany], Patricia Vannier [CDS] 27-Oct-2010
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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