The mid-infrared environments of 6.7 GHz Methanol Masers from the
  Methanol Multi-Beam Survey
  We present a study of the mid-infrared environments and association with star
formation tracers of 6.7 GHz methanol masers taken from the Methanol Multi-Beam
(MMB) Survey. Our ultimate goal is to establish the mass of the host star and
its evolutionary stage for each maser site. As a first step, the GLIMPSE survey
of the Galactic Plane is utilised to investigate the environment of 776
methanol masers and we find that while the majority of the masers are
associated with mid-infrared counterparts, a significant fraction (17%) are not
associated with any detectable mid-infrared emission. A number of the maser
counterparts are clearly extended with respect to the GLIMPSE point spread
function and we implement an adaptive non-circular aperture photometry (ANCAP)
technique to determine the fluxes of the maser counterparts. The ANCAP
technique doubles the number of masers with flux information at all four
wavelengths compared to the number of the corresponding counterparts obtained
from the GLIMPSE Point Source Catalogue. The colours of the maser counterparts
are found to be very similar to the smaller study carried out by Ellingsen
(2006). The MMB masers are weakly associated with Extended Green Objects (EGOs)
and Red MSX Survey (RMS) embedded sources (YSO and HII classifications) with
18% and 12% of masers associated with these objects respectively. The majority
of MMB masers (60%) have detectable GLIMPSE infrared counterparts but have not
been identified with previously recognised tracers of massive star formation;
this confirms that the MMB survey has the potential to identify massive star
forming regions independent of infrared selection.
