The LSST primary/tertiary mirror experienced a successful High Fire over the weekend of March 28 & 29th, 2008, reaching a peak temperature of approximately 1165∫C (2125∫F). (See this video [MPEG] taken inside the oven over high fire). This event is the critical first step in fabricating the key optical components of the LSST, a unique wide-field survey telescope. The LSST mirror will now anneal and cool gradually to room temperature over the next 100 days in the slowly rotating oven of the UA Steward Observatory Mirror Lab, and will be removed for grinding and polishing in mid-August. More images are to be added as time allows.