1999AJ....118.1791M

We present the first very long baseline interferometric observations of the 6₁₆-5₂₃, 22 GHz H₂O maser emission associated with a proto-planetary nebula candidate. We obtained three epochs of observation of the water masers associated with IRAS 19296+2227, using the Very Long Baseline Array, operated by the National Radio Astronomy Observatory. These observations show that the water masers are distributed over a 50 mas arclike structure covering a limited velocity range of ∼9 km.s^–1. The masers most likely reside in an asymptotic giant branch-like circumstellar shell, although we cannot rule out the possibility that they lie in a shocked region. Over the 40 days spanning the epochs of observation, we have measured an error-weighted average proper motion of 6.16±1.32 km.s^–1, indicating that the masers are not in a high-velocity outflow.