Class I methanol masers in NGC253: Alcohol at the end of the bar
  We have used the Australia Telescope Compact Array (ATCA) to observe the
36.2-GHz class I methanol maser emission towards NGC253 and find that it is
located at the interface between the nuclear ring and both ends of the galactic
bar. This is thought to be the location of the inner Linblad resonance and we
suggest that the maser emission in this region is likely due to large-scale
cloud-cloud collisions. We have detected the first extragalactic 44.1-GHz class
I methanol maser and find that it is associated with the 36.2-GHz maser
emission. In contrast to the class I methanol masers found in Galactic star
formation regions, the 44.1-GHz emission in NGC253 is two orders of magnitude
weaker than the 36.2-GHz masers. Both the 36.2- and 44.1- GHz emission is
orders of magnitude stronger than expected from typical high-mass star
formation regions. This demonstrates that the luminous class I methanol masers
observed in NGC253 are significantly different from those associated with
Galactic star formation.
