2016A&A...589A.106M

We present new observations of the cataclysmic variable (CV) V523 Lyr, a member of the open cluster NGC 6791. The Kepler Space telescope obtained photometric observations of this source and we examine the nearly three-year-long light curve. The observations show numerous small amplitude outbursts recurring on average every 33 d, intermittent quasi-periodic oscillations, and a significant fully coherent period of ∼3.8h, which we identify as the orbital period of the binary. Contemporaneous optical spectroscopy of V523 Lyr reveals a faint blue source with broad Balmer absorption lines containing narrow emission cores. Hα is in emission above the continuum. The low amplitude of the photometric signal and no detected velocity motion suggest a low orbital inclination. We discuss the properties of V523 Lyr and show that it is a member of the growing group of anomalous Z Cam type CVs, systems that show stunted outbursts, light curve standstills, and occasional deep drops in brightness.