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II/330 Northern sky photometric catalog of 44 million sources (Madsen+ 2013)
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Beginning of ReadMe :II/330 Northern sky photometric catalog of 44 million sources (Madsen+ 2013)
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A precision multi-band two-epoch photometric catalog of 44 million sources in
the northern sky from a combination of the USNO-B and Sloan Digital Sky Survey
catalogs.
Madsen G.J., Gaensler B.M.
<Astrophys. J. Suppl. Ser., 209, 33 (2013)>
=2013ApJS..209...33M
=2014yCat.2330....0M
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ADC_Keywords: Surveys; Photometry, SDSS
Keywords: catalogs - methods: data analysis - quasars: general -
stars: variables: general - techniques: photometric
Abstract:
A key science driver for the next generation of wide-field optical and
radio surveys is the exploration of the time variable sky. These
surveys will have unprecedented sensitivity and areal coverage, but
will be limited in their ability to detect variability on time scales
longer than the lifetime of the surveys. We present a new precision,
multi-epoch photometric catalog that spans 60 yr by combining the US
Naval Observatory-B (USNO-B) and Sloan Digital Sky Survey (SDSS) Data
Release 9 (DR9) catalogs. We recalibrate the photometry of the
original USNO-B catalog and create a catalog with two epochs of
photometry in up to five different bands for 43,647,887 optical point
sources that lie in the DR9 footprint of the northern sky. The
recalibrated objects span a magnitude range 14< m< 20 and are
accurate to 0.1mag. We minimize the presence of spurious
objects and those with inaccurate magnitudes by identifying and
removing several sources of systematic errors in the two originating
catalogs, with a focus on spurious objects that exhibit large apparent
magnitude variations. After accounting for these effects, we find
250,000 stars and quasars that show significant (>=4sigma)
changes in brightness between the USNO-B and SDSS DR9 epochs. We
discuss the historical value of the catalog and its application to the
study of long time scale, large amplitude variable stars and quasars.