  We present time-resolved spectrophotometry of GK Per taken on the rise to
outburst maximum, in which we detect 5000 s QPOs in the optical emission lines.
We use this opportunity to provide a kinematically-resolved analysis of the
phenomenon. Observations are consistent with reprocessing off blobs of gas
orbiting within the inner accretion disc, and evidence is found for the
migration of the QPO source towards the compact star over orbital timescales.
