The relative intensities of vibronic splitting components of the 3A2g → 1T2g optical electronic dipole transition induced by odd local vibrations and spin-orbit interaction are calculated for an impurity center with Oh point-group symmetry. The polarization dependences and magnetic circular dichroism (MCD) are found for the vibronic components in an external magnetic field. In contrast with the previous works, the calculation is not confined to the nearest-term approximation. It is shown that measurements of the polarization dependences and MCD allow one to identify unambiguously the vibronic components. A comparison with the experiment is carried out for the Ni2+ ion in CaO.