J/ApJS/186/233 Variable point sources in SDSS stripe 82. I. (Bhatti+, 2010)
Variable point sources in Sloan Digital Sky Survey stripe 82.
I. Project description and initial catalog (0hr≤α≤4hr).
Bhatti W.A., Richmond M.W., Ford H.C., Petro L.D.
<Astrophys. J. Suppl. Ser., 186, 233-258 (2010)>
=2010ApJS..186..233B 2010ApJS..186..233B
ADC_Keywords: Binaries, eclipsing ; Stars, variable ; Surveys ;
Photometry, ugriz ; Photometry, SDSS
Keywords: binaries: eclipsing - catalogs - stars: variables: general - surveys
Abstract:
We report the first results of a study of variable point sources
identified using multi-color timeseries photometry from Sloan Digital
Sky Survey (SDSS) Stripe 82, including data from the SDSS-II Supernova
Survey, over a span of nearly 10 years (1998-2007). We construct a
light-curve catalog of 221842 point sources in the R.A. 0-4hr half
of Stripe 82, limited to r=22.0mag, that have at least 10
detections in the ugriz bands and color errors <0.2mag. These
sources are then classified by color and by cross matching them to
existing SDSS catalogs of interesting objects. Inhomogeneous ensemble
differential photometry techniques are used to greatly improve our
sensitivity to variability and reduce contamination by sources that
appear variable due to large photometric noise or systematic effects
caused by non-uniform photometric conditions throughout the survey. We
use robust variable identification methods to extract 6520 variable
candidates from this data set, resulting in an overall variable
fraction of ∼2.9% at the level of ∼0.05mag variability. Despite the
sparse and uneven time sampling of the light-curve data, we discover
143 periodic variables in total. Due to period ambiguity caused by
relatively poor phase coverage, we identify a smaller final set of 101
periodic variables with well-determined periods and light curves.
Among these are 55 RR Lyrae, 30 eclipsing binary candidates, and 16
high-amplitude Delta Scuti variables. In addition to these objects, we
also identify a sample of 2704 variable quasars matched to the SDSS
Quasar Catalog, which make up a large fraction of our variable
candidates. An additional 2403 quasar candidates are tentatively
identified and selected by their non-stellar colors and variability. A
sample of 11328 point sources that appear to be nonvariable given the
limits of our variability sensitivity is also briefly discussed.
Finally, we describe several interesting objects discovered among our
eclipsing binary candidates, and illustrate the use of our publicly
available light-curve catalog by tracing Galaxy halo substructure with
our small sample of RR Lyrae variables.
Description:
The SDSS uses a dedicated 2.5m telescope located at the Apache Point
Observatory in New Mexico. Stripe 82 is on the celestial equator,
ranging from 20hr to 4hr in right ascension and -1.27° to +1.27°
in declination, for a total area of about 300deg2. The Stripe has
been observed many times over the 10 years of operation of SDSS and
SDSS-II, mostly during the fall (September-December).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 97 32 *Eclipsing and ellipsoidal binary candidates
table7.dat 73 55 RRab and RRc RR Lyrae variables
table8.dat 68 16 High-amplitude Delta Scuti variables
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Note on table6.dat : in addition to the 30 newly discovered binaries, we
have also recovered two confirmed low-mass eclipsing binaries present
in the footprint of Stripe 82: objects a and b in f_SDSS of table 6.
See section 4.4.1 for further details.
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See also:
II/294 : SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/AJ/115/296 : SDSS new variables (Henden+ 1998)
J/AJ/130/1640 : Photometry of candidate RR Lyrae stars in the SDSS (Wu+, 2005)
J/A+A/510/A100 : Four new SDSS eclipsing systems (Southworth+, 2010)
http://shrike.pha.jhu.edu/stripe82-variables : SDSS Stripe 82 Variable Stars
project web site
Byte-by-byte Description of file: table6.dat table7.dat table8.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS SDSS identification (JHHMMSS.ss+DDMMSS.s)
26 A1 --- n_SDSS [ab ] confirmation of previous discovery (1)
28- 30 I3 --- Obs Observation number
32- 36 F5.2 mag umag SDSS median u-band magnitude
38- 42 F5.2 mag gmag SDSS median g-band magnitude
44- 48 F5.2 mag rmag SDSS median r-band magnitude
50- 54 F5.2 mag imag SDSS median i-band magnitude
56- 60 F5.2 mag zmag SDSS median z-band magnitude
62- 68 F7.5 d Per Period
70- 97 A28 --- Comm Comments (SpType and noteworthy features of
light curves for table 6, SpType for
table 7)
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Note (1): Flags as follows:
a = This is the confirmed eclipsing binary found by Becker et al.
(2008MNRAS.386..416B 2008MNRAS.386..416B): 2MASS J01542930+0053266
b = This is the confirmed eclipsing binary found by Blake et al.
(2008ApJ...684..635B 2008ApJ...684..635B): SDSS J031823.88-010018.4
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 19-Apr-2010