  We have detected coherent oscillations, at multiple frequencies, in the line
and continuum emission of the eclipsing dwarf nova V2051 Ophiuchi using the 10m
Keck II telescope. Our own novel data acquisition system allowed us to obtain
very fast spectroscopy using a continuous readout of the CCD on the LRIS
spectrograph. This is the first time that dwarf nova oscillations are detected
and resolved in the emission lines. The accretion disc is highly asymmetric
with a stronger contribution from the blue-shifted side of the disc during our
observations. The disc extends from close to the white dwarf out to the outer
regions of the primary Roche lobe.
  Continuum oscillations at 56.12s and its first harmonic at 28.06 s are most
likely to originate on the surface of a spinning white dwarf with the
fundamental period corresponding to the spin period. Balmer and Helium emission
lines oscillate with a period of 29.77s at a mean amplitude of 1.9%. The line
kinematics as well as the eclipse constraints indicate an origin in the
accretion disc at a radius of 12 R_wd. The amplitude of the emission line
oscillation modulates (0-4%) at a period of 488s, corresponding to the Kepler
period at R=12 R_wd. This modulation is due to the beating between the white
dwarf spin and the orbital motion in the disc.
  The observed emission line oscillations cannot be explained by a truncated
disc as in the intermediate polars. The observations suggest a non-axisymmetric
bulge in the disc, orbiting at 12R_wd, is required. The close correspondence
between the location of the oscillations and the circularisation radius of the
system suggests that stream overflow effects may be of relevance
