Program: GS-2005A-Q-57

We propose to continue our survey of giant HII regions, aimed at studying the nature of massive star formation and tracing the spiral structure of our Galaxy. Our distance determinations are based upon spectroscopic parallaxes of newly born OB stars. Our recent results have revealed clusters containing ZAMS OB stars and massive young objects still accreting matter. Our near infrared survey of Galactic GHII regions, when complete, will provide a complete database of the stellar content of the known radio selected clusters in the Galaxy which harbor nacent massive star clusters. In the current proposal, we propose to use GNIRS on Gemini South to make a first detailed study of G331.5-0.1, a cluster imaged as part of our survey on the Blanco 4m telescope at CTIO. G331.5-0.1, like our previous clusters, appears to harbor massive OB stars and massive young stellar objects.