We report H _ { 2 } O masers associated with the massive-star forming region G192.16 - 3.84 observed with the new Japan VLBI network at three epochs spanned for two months , which have revealed the three-dimensional kinematical structure of the whole H _ { 2 } O maser region in G192.16 - 3.84 , containing two young stellar objects separated by \sim 1200 AU .
The maser spatio-kinematical structure has well persisted since previous observations , in which the masers are expected to be associated with a highly-collimated bipolar jet and an infalling-rotating disk in the northern and southern clusters of H _ { 2 } O maser features , respectively .
We estimated a jet expansion speed of \sim 100 km s ^ { -1 } and re-estimated a dynamical age of the whole jet to be 5.6 \times 10 ^ { 4 } yrs .
We have investigated the spatial distribution of Doppler velocities during the previous and present observations and relative proper motions of H _ { 2 } O maser features in the southern cluster , and a relative bulk motion between the two maser clusters .
They are well explained by a model of an infalling–rotating disk with a radius of \sim 1000 AU and a central stellar mass of 5–10 M _ { \odot } , rather than by a model of a bipolar jet perpendicular to the observed CO outflow .
Based on the derived H _ { 2 } O maser spatio-kinematical parameters , we discuss the formation mechanism of the massive young stellar objects and the outflow development in G192.16 - 3.84 .