Time-resolved photometry of GK persei during the 1996 outburst

GK Per is a unique cataclysmic variable star which has shown a nova explosion as well as dwarf nova-type outbursts, and has an intermediate-polar nature. We carried out V-band time-resolved photometry and B-band monitoring during the 1996 outburst. This outburst lasted for about 60 d, and was divided into three parts: a slow-rise branch for 35 d, a gradual-decay branch with a decay rate of 20.0d mag(-1) for similar to 16d, and a rapid-decline branch with a rate of 5.6d mag(-1) for similar to 10d. The B - V color became bluest (B - V similar to 0.18) at about 10d before the outburst maximum, which supports an idea that the outburst in GK Per is of the inside-out type. The spin pulse, 440-s quasi periodic oscillations (QPOs), and similar to 5000-s QPOs were detected in our light curve, as previously seen in X-ray and optical observations. In addition, we report on the discovery of an similar to 300-s periodicity, which is shorter than the spin period.