Mapping the circumnuclear matter of NGC 1068 in X-rays

An energy-dependent variation of the X-ray emission from the archetypical " Compton-thick" Seyfert 2 galaxy NGC 1068 has been observed between two Bepp oSAX observations, performed one year apart. This variation is highest in t he 3-10 keV band and declines towards lower and higher energies. The most s traightforward explanation is a flattening of the primary nuclear continuum , which is scattered along our line of sight by an electron plasma. If this is indeed the case, this evidence allows us to obtain the first direct est imate of the location of the scattering medium, at similar to 1 pc from the nucleus. (C) 2000 Elsevier Science B.V. All rights reserved.