  We report the result of an on-going survey for 22 GHz H2O maser emission
towards infrared luminous galaxies. The observed galaxies were selected
primarily from the IRAS bright galaxy sample. The survey has resulted in the
detection of one new maser. The new maser was discovered towards the
[U]LIRG/merger galaxy NGC6240, which contains a LINER nucleus. This is the
first detection of an H2O maser towards this class of galaxy, they are
traditionally associated with OH megamaser sources. The detected maser emission
is highly redshifted (~ 260-300 km/s) with respect to the adopted systemic
velocity of the galaxy, and we identified no other significant emission at
velocities < +- 500 km/s relative to the systemic velocity. The presence of
high-velocity maser emission implies the possible existence of a rotating maser
disk formed in the merging process. The large maser luminosity (~ 40 Lo)
suggests that an active galactic nucleus could be the energy source that gives
rise to the water emission. Alternatively, the maser emission could be
associated with the previously observed double radio source in the centre of
the galaxy. Interferometric observations with high angular resolution will be
able to clarify the origin of the new maser.
