VLBI observations of the G25.65+1.05 water maser superburst
  This paper reports observations of a 22 GHz water maser `superburst' in the
G25.65+1.05 massive star forming region, conducted in response to an alert from
the Maser Monitoring Organisation (M2O). Very long baseline interferometry
(VLBI) observations using the European VLBI Network (EVN) recorded a maser flux
density of $1.2 \times 10^{4}$ Jy. The superburst was investigated in the
spectral, structural and temporal domains and its cause was determined to be an
increase in maser path length generated by the superposition of multiple maser
emitting regions aligning in the line of sight to the observer. This conclusion
was based on the location of the bursting maser in the context of the star
forming region, its complex structure, and its rapid onset and decay.
