Light and motion in SDSS Stripe 82: the catalogues

Abstract

We present a new public archive of light-motion curves in Sloan Digital Sky Survey (SDSS) Stripe 82, covering 99° in right ascension from $\alpha = 20^{\mathrm h}\!\!.7$ to $3^{\mathrm h}\!\!.3$ and spanning $2^{\circ}\!\!.52$ in declination from $\delta = -1^{\circ}\!\!.26$ to $1^{\circ}\!\!.26$ , for a total sky area of ∼249 deg 2 . Stripe 82 has been repeatedly monitored in the u, g, r, i and z bands over a seven-year baseline. Objects are cross-matched between runs, taking into account the effects of any proper motion. The resulting catalogue contains almost 4 million light-motion curves of stellar objects and galaxies. The photometry are recalibrated to correct for varying photometric zero-points, achieving ∼20 and 30 mmag rms accuracy down to 18 mag in the g, r, i and z bands for point sources and extended sources, respectively. The astrometry are recalibrated to correct for inherent systematic errors in the SDSS astrometric solutions, achieving ∼32 and 35 mas rms accuracy down to 18 mag for point sources and extended sources, respectively. For each light-motion curve, 229 photometric and astrometric quantities are derived and stored in a higher level catalogue. On the photometric side, these include mean exponential and point spread function (PSF) magnitudes along with uncertainties, rms scatter, χ 2 per degree of freedom, various magnitude distribution percentiles, object type (stellar or galaxy), and eclipse, Stetson and Vidrih variability indices. On the astrometric side, these quantities include mean positions, proper motions as well as their uncertainties and χ 2 per degree of freedom. The light-motion curve catalogue presented here is complete down to r∼ 21.5 and is at present the deepest large-area photometric and astrometric variability catalogue available.