CCD Photometry of a Newly Confirmed SU UMa-Type Dwarf Nova, NSV 4838

We present time-resolved CCD photometry of a dwarf nova, NSV 4838 (UMa 8, SDSS J102320.27+440509.8), during 2005 June and 2007 February outbursts. The two light curves showed superhumps with mean periods of 0.0699(1) d for the 2005 outburst and 0.069824(83) d for the 2007 outburst. Using its known orbital period of 0.0678 d, we estimated the mass ratio of the system to be q = 0.13 based on an empirical relation. Although the majority of SU UMa-type dwarf novae having similar superhump periods show negative period derivatives, we found that the superhump period increased at P P= Psh =+ 7(+3, � 4) � 10 � 5 during the 2007 superoutburst. We also