The Extraordinary Outburst in the Massive Protostellar System
  NGC6334I-MM1: Spatio-kinematics of Water Masers during a Contemporaneous
  Flare Event
  Following an eruptive accretion event in NGC6334I-MM1, flares in the various
maser species, including water masers, were triggered. We report the observed
relative proper motion of the highly variable water masers associated with the
massive star-forming region, NGC6334I. High velocity H$_2$O maser proper
motions were detected in 5 maser clusters, CM2-W2 (bow-shock structure),
MM1-W1, MM1-W3, UCHII-W1 and UCHII-W3. The overall average of the derived
relative proper motion is 85 km s$^{-1}$. This mean proper motion is in
agreement with the previous results from VLA multi-epoch observations. Our
position and velocity variance and co-variance matrix analyses of the maser
proper motions show its major axis to have a position angle of $-$79.4$^\circ$,
cutting through the dust cavity around MM1B and aligned in the
northwest-southeast direction. We interpret this as the axis of the jet driving
the CM2 shock and the maser motion. The complicated proper motions in MM1-W1
can be explained by the combined influence of the MM1 northeast-southwest
bipolar outflow, CS(6-5) north-south collimated bipolar outflow, and the radio
jet. The relative proper motions of the H$_2$O masers in UCHII-W1 are likely
not driven by the jets of MM1B protostar but by MM3-UCHII. Overall, the
post-accretion burst relative proper motions of the H$_2$O masers trace shocks
of jet motion.
