Applications of precision astrometry to studies of massive YSOs
  We present VLBI observations of the H$_2$O maser emission towards a selection of massive young stellar objects (YSOs). In one of these sources, IRAS20126+4104, the measured proper motions confirm that the water masers spots are tracing the very root (around 100 AU) of a conical bipolar outflow emerging near the position of the embedded YSO, and are an excellent tool to investigate the structure and kinematics of the outflow/jet. We also present preliminary results of a first epoch EVN observations of a selection of 5 high-mass YSO to assess the precise association of maser spots and molecular outflows in these sources. 
M.J. Rioja (1), L. Moscadelli (2), R. Cesaroni (3) ((1) Observatorio   Astronomico Nacional, Spain, (2) Osservatorio Astrono...