A thin HI circumnuclear disk in NGC 4261

We report on high sensitivity, spectral line VLBI observations of the HI ab sorption feature in the radio galaxy NGC 4261. Although absorption is only detectable on the most sensitive baseline, it can be unambiguously associat ed with the counterjet and is interpreted to originate in a thin atomic cir cumnuclear disk. This structure is probably a continuation of the dusty acc retion disk inferred from HST imaging, which could be feeding the massive b lack hole. Il I column densities in front of the counterjet of the order of 10(21)(T-sp/100 K) cm(-2) are derived, consistent with X-ray data and VLBI scale free-free absorption. The data presented here are the result of the first scientific project processed on the new EVN MkIV data processor.