Methanol masers are common phenomena in star-forming regions. They are divided into two classes: class I masers are pumped by collisions and arise in shocked gas, while class II masers are excited by infrared radiation and reside in close environments of massive young stellar objects (YSOs). The Australia Telescope Compact Array (ATCA) is well suited for maser observations due to its frequency coverage, spectral resolution and flexibility. It has recently been used for high angular resolution imaging of the most common class I methanol masers at 36 and 44 GHz. This is the largest survey of this kind available to date (and the first one in the Southern hemisphere) which allowed us to see statistical patterns for the first time. In particular, the number of maser components was found to fall exponentially with the projected linear distance from the presumed location of a YSO. This distribution has a scale of 263+/-15 milliparsec. The class I masers associated with OH masers, which are widely regarded to be somewhat more evolved sources, were found to be more spread out, both spatially and in the velocity domain. Apart from a small number of high-velocity components (which are largely blue-shifted and predominantly seen at 36 GHz), the velocity distribution is well approximated by a Gaussian, peaking near the systemic velocity of the region (estimated as a middle of the velocity interval of the associated 6.7 GHz maser). The mean indicated a small, but significant blue-shift asymmetry of -0.57 km/s (uncertainties are 0.06 and 0.07 km/s for the 36 and 44 GHz masers, respectively). We also demonstrate associations, at arcsecond precision, of the class I methanol masers with outflows, expanding HII regions, dark clouds and shocks traced by the 4.5-micron emission and 8.0-micron filaments. The current capabilities of the ATCA and the status of the Australian Square Kilometre Array Pathfinder (ASKAP), which is currently being built in Western Australia, will also be described for the benefits of a wider audience.

Page created on June 9, 2014.