Program: GS-2004A-Q-54

We propose to employ the imaging capabilities of Gemini MOS together with the Sloan u'g'r'i'z' filter set to observe faint, unevolved main sequence stars in a representative sample of Galactic globular clusters. This type of program is optimized to yield highly profitable results during poor seeing conditions by targetting areas of the cluster that lie a reasonable distance away from the densely crowded core region. Ultimately, the GMOS data will be supplemented with proposed CFHT MegaPrime observations of the brighter giant and turnoff stars within the same clusters to yield a precise set of stellar fiducial sequences for the Sloan photometric system which encompass the full range of stellar evolutionary phase and metallicity. Apart from the benefits these sequences will have for the exploitation of future stellar populations data resulting from such projects as the Sloan Digital Sky Survey, the CFH Legacy Survey, and other GMOS imaging studies, we also intend to use the Gemini data to provide stringent empirical constraints for theoretical stellar models and Sloan filter color-temperature relations for lower main sequence stars. Moreover, the depth of the GMOS observations will be ideal for detailed investigations into both the mass-luminosity relationship for extremely low mass metal-poor stars as well as the white dwarf components of a variety of globular clusters.