Abstract
Using the Effelsberg 100-m telescope, sensitive measurements of the H2O megamaser in NGC 3079 are presented. During 2000–2001, “high velocity” features are seen that are red-shifted up to 225 with respect to the systemic velocity of the galaxy (VLSR ~ 1120 ). Symmetrically bracketing the systemic velocity, the H2O emission covers a velocity range of ~450 with only one potential narrow gap (~20 ) near the systemic velocity itself. Velocity drifts of individual components are not convincingly detected. It is shown that the presence of red-shifted emission and the absence of detectable velocity drifts are not inconsistent with the existence of a rotating circumnuclear maser disk at the very center of the galaxy. Significant differences in the overall line profile compared to NGC 4258 and a complex morphology of the radio continuum leave, however, space for scepticism.