  We study transport properties of a non-degenerate two-dimensional system of
non-interacting electrons in the presence of a quantizing magnetic field and a
short-range disorder potential. We show that the low-frequency
magnetoconductivity displays a strongly asymmetric peak at a nonzero frequency.
The shape of the peak is restored from the calculated 14 spectral moments, the
asymptotic form of its high-frequency tail, and the scaling behavior of the
conductivity for omega -> 0. We also calculate 10 spectral moments of the
cyclotron resonance absorption peak and restore the corresponding
(non-singular) frequency dependence using the continuous fraction expansion.
Both expansions converge rapidly with increasing number of included moments,
and give numerically accurate results throughout the region of interest. We
discuss the possibility of experimental observation of the predicted effects
for electrons on helium.
