  GK Persei is an intermediate polar that exhibits a dwarf nova outburst
approximately every 1000 days. During previous outbursts the system has
displayed kilo-second quasi-periodic oscillations (QPOs) in X-ray emission.
These oscillations are unique in that they are an order of magnitude longer
than QPOs usually observed in disc-fed cataclysmic variables. We have detected
the optical counterpart of these QPOs in spectrophotometry collected during the
1996 outburst. The presence of these QPOs in Doppler-broadened emission lines
originating from the highly-supersonic accretion flow enables us to place
useful constraints on the location of the QPO source and its formation
mechanism.
