2009AJ....138.1435O

We analyze eight years (1999-2007) of automated photometric observations of the active Algol binary UX Monocerotis to search for mass transfer bursts similar to those seen in U Cephei. The largest photometric anomaly is the mean gainer luminosity difference between the stream-impact hemisphere and the opposite hemisphere. We find an updated Wilson-Devinney solution for earlier six-color observations. The UX Mon donor star fills its Roche lobe and the gainer nearly fills its rotational lobe. Instead of isolated bursts of the U Cep type, we found nearly continuous brightness fluctuations likely produced by variable mass transfer. We discuss implications for mass transfer.