Uncovering the earliest stages of massive star formation

Massive stars begin their lives in cold, dense cores which are much more massive than the stars which form in them. We summarise the results of a program to find the earliest examples of massive star formation, and to examine the evolutionary sequence of events that occurs as such a star begins to form and heat its surroundings. Methanol maser emission has proved to be a particularly potent tool to locate such cores, though there are also clearly many massive cores which do not exhibit such maser emission. Our program began with a survey for 6.6 GHz methanol maser emission, but expanded to include dust continuum surveys in the mm and sub-mm, a survey for hot molecular cores associated with 'isolated' masers through mmline CH₃CN emission, and follow-up probing of some cores through sub-arcsecond, diffraction limited observations in the mid-IR. This program is outlined below.