Physical conditions around 6.7 GHz methanol masers-I: Ammonia
  Methanol masers at 6.7 GHz are known to be tracers of high-mass star
formation in our Galaxy. In this paper, we study the large scale physical
conditions in the star forming clumps/cores associated with 6.7 GHz methanol
masers using observations of the (1,1), (2,2) and (3,3) inversion transitions
of ammonia with the Effelsberg telescope. The gas kinetic temperature is found
to be higher than in infrared dark clouds, highlighting the relatively evolved
nature of the maser sources. Other than a weak correlation between maser
luminosity and the ammonia line width, we do not find any differences between
low and high luminosity methanol masers.
