2015AJ....150..188S

We report on candidate active galactic nuclei (AGNs) discovered during the monitoring of ∼500 bright (r < 18 mag) galaxies over several years with the Kepler Mission. Most of the targets were sampled every 30 minutes nearly continuously for a year or more. Variations of 0.001 mag and often less could be detected reliably. About 4.0% (19) of our random sample continuously fluctuated with amplitudes increasing with longer timescales, but the majority are close to the limits of detectability with Kepler. We discuss our techniques to mitigate the long term instrumental trends in Kepler light curves and our resulting structure function (SF) curves. The amplitudes of variability over three month periods, as seen in the SFs and power spectral densities (PSDs), can dramatically change for many of these AGN candidates. Four of the candidates have features in their SFs that may indicate quasi-periodic behavior, although other possibilities are discussed. Fundamental Parameters