The SU UMa nature of the dwarf nova, DM lyrae

We carried out time-resolved V-band photometry of DM Lyr during long outbursts in 1996 July and in 1996 February-March at Ouda Station, Kyoto University, and at Osaka Kyoiku University. Since superhumps were clearly detected in the light curves, DM Lyr was first identified as being an SU UMa-type dwarf nova. The superhump period is 0.0673(2) d. and the superhump excess is 2.8(3)%. The duration of the superoutburst, the outburst amplitude, the decline rate in the plateau phase, and the superhump excess were typical values for a usual SU UMa star. According to visual and CCD observations reported to VSNET, this star has experienced a dramatic change of the outburst pattern from a superoutburst phase to a normal outburst phase. There may exist mechanisms to decrease the number of normal outbursts between two successive superoutbursts and to elongate the recurrence cycle of the superoutburst.