  We present a simulation showing that super-Nyquist frequencies may have
periodic amplitude and frequency modulations, even if actually stable, in time
series sampled like the Kepler data. These modulations are caused by the
barycentric time correction, which destroys the evenly spaced time
measurements, making the Nyquist frequency variable over the spacecraft orbit
around the Sun. These modulations can easily be identified in pulsating stars
from Kepler's photometric data.
