A Technique for Ultrahigh-Precision CCD Photometry

We present techniques for wide-field ultrahigh-precision time-sampled CCD photometry. Representing a survey of field stars, our data consist of UBVRI photometry and a V-band time series of exposures on 5 consecutive nights covering 11,500 stars in a ∼1 deg field. The resulting light curves reach precisions of 0.0020 mag per exposure in the brightest stars ( ). Light curves binned and averaged over 4.5 hr reach V ∼ 14 precisions of 0.00019 mag for the brightest stars. We present example light curves and discuss one application for surveys of this type: the search for transits by extrasolar planets.