  The influence of isolated impurity atoms on the electron energy spectrum in a
parabolic quantum dot in quantizing magnetic field is studied. The impurity
potential is approximated by a Gaussian separable operator which allows one to
obtain the exact solution of the problem. We demonstrate that in the electron
energy spectrum there is a set of local levels which are split from the Landau
zone boundaries in the upward or downward direction depending on the impurity
type. We have calculated the local level positions, the wave functions of
electrons in bound states, and the residues of the electron scattering
amplitudes by impurity atoms at the poles.
