  We make measurements of power spectral density of the microwave voltage
emitted by a spin torque nano-oscillator (STNO) and compare our experimental
results to predictions of an analytic theory of a single-mode STNO dynamics by
V. S. Tiberkevich, A. N. Slavin, J. V. Kim,[Phys. Rev. B 78, 092401 (2008)]. We
find that a complete set of the oscillator spectral properties: power,
frequency, spectral line width and line shape as functions of current are
self-consistently described by the analytic theory for moderate amplitudes of
oscillations (< 70 degrees).
