Detection of 36 GHz Class I Methanol Maser Emission Towards NGC 4945
  We have searched for emission from the 36.2 GHz ($4_{-1} \rightarrow 3_0$E)
methanol transition towards NGC 4945, using the Australia Telescope Compact
Array. 36.2 GHz methanol emission was detected offset south-east from the
Galactic nucleus. The methanol emission is narrow, with a linewidth <10
kms$^{-1}$, and a luminosity five orders of magnitude higher than Galactic
class I masers from the same transition. These characteristics combined the
with physical separation from the strong central thermal emission suggests that
the methanol emission is a maser. This emission is a factor of $\sim90$ more
luminous than the widespread emission detected from the Milky Way central
molecular zone (CMZ). This is the fourth detection of extragalactic class I
emission, and the third detection of extragalactic 36.2 GHz maser emission.
These extragalactic class I methanol masers do not appear to be simply highly
luminous variants of Galactic class I emission, and instead appear to trace
large-scale regions of low-velocity shocks in molecular gas, which may precede,
or be associated with, the early stages of large-scale star formation.
