Positions of the radio recombination line masers in MWC 349

The Owens Valley Millimeter Interferometer has been used at 232 GHz to measure the relative positions of the strongest H30α maser features toward MWC 349. Maser emission appears to originate from two positions 0″.065±0″.005 (80 AU) apart, located in an almost east-west direction (P.A. 107°±7°), approximately perpendicular to the bipolar ionized wind structure observed in low-frequency radio continuum maps. We argue that the maser features originate in two positions associated with a nearly edge-on, neutral disk which is the source of high-density ionized gas