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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 358579.0, MPI für Astronomie / Publikationen_mpia
Exploring the variable sky with the Sloan Digital Sky Survey
Authors:Sesar, B.; Ivezic, Z.; Lupton, R. H.; Juric, M.; Gunn, J. E.; Knapp, G. R.; De Lee, N.; Smith, J. A.; Miknaitis, G.; Lin, H.; Tucker, D.; Doi, M.; Tanaka, M.; Fukugita, M.; Holtzman, J.; Kent, S.; Yanny, B.; Schlegel, D.; Finkbeiner, D.; Padmanabhan, N.; Rockosi, C. M.; Bond, N.; Lee, B.; Stoughton, C.; Jester, S.; Harris, H.; Harding, P.; Brinkmann, J.; Schneider, D. P.; York, D.; Richmond, M. W.; Vanden Berk, D.
Date of Publication (YYYY-MM-DD):2007
Title of Journal:The Astronomical Journal
Start Page:2236
End Page:2251
Audience:Not Specified
Abstract / Description:We quantify the variability of faint unresolved optical sources using a catalog based on multiple SDSS imaging observations. The catalog covers SDSS stripe 82, which lies along the celestial equator in the southern Galactic hemisphere (22h24m<alphaJ2000.0<04h08m, -1.27deg<deltaJ2000.0<+1.27deg, ~290 deg2), and contains 34 million photometric observations in the SDSS ugriz system for 748,084 unresolved sources at high Galactic latitudes (b<-20deg) that were observed at least four times in each of the ugri bands (with a median of 10 observations obtained over ~6 yr). In each photometric bandpass we compute various low-order light-curve statistics, such as rms scatter, chi2 per degree of freedom, skewness, and minimum and maximum magnitude, and use them to select and study variable sources. We find that 2% of unresolved optical sources brighter than g=20.5 appear variable at the 0.05 mag level (rms) simultaneously in the g and r bands (at high Galactic latitudes). The majority (2 out of 3) of these variable sources are low-redshift (<2) quasars, although they represent only 2% of all sources in the adopted flux-limited sample. We find that at least 90% of quasars are variable at the 0.03 mag level (rms) and confirm that variability is as good a method for finding low-redshift quasars as the
Free Keywords:Galaxy: Halo; Galaxy: Stellar Content; Galaxies: Quasars: General; Stars: Population II; Stars: Variables: Other
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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