ИСТИНА

The multi-site photometric observations of MN Dra were made over 77 nights in August-November, 2009. The total exposure was 433 hours. During this time the binary underwent two superoutburst and five normal outbursts. During the course of superoutbursts the positive superhumps decreased with extremely large dP/P=3-8x10{-4} for SU UMa-like dwarf novae, confirming the known behaviour of MN Dra in 2003 (Kato et al., 2009). As it was suggested earlier (Pavlenko et al. 2010), MN Dra displayed large amplitude (up to 1.4 mag in quiescence and 0.1-0.2 mag in normal outbursts) periodical signal of a mean value 0.096 day that was believed to be a negative superhump. It was shown that superhump period varies cyclically from 0.0964 day to 0.0956 day between normal outbursts, being the longest one at the end of quiescent state preceding the normal outburst. These variations took like a jump-like switching of this period from the longest value to the shortest one during the beginning of a normal outburt and subsecuent smooth increase to its previous value.