Program: GN-2012B-Q-109

White dwarfs are the end stage for all stars with mass < 8 Msun, and the coolest can constrain the age of the Galactic disk and halo. These cool, Earth-sized, high proper motion stars are very faint, and can be confused with subdwarfs. Spectroscopic confirmation is required, and both optical and infrared photometry is also required. The photometry is necessary for determining the chemical composition and temperature of the atmosphere, and hence the cooling age, of these remnants of the original population of the Galaxy. We have paired the UKIRT and Sloan sky surveys to identify candidates, and have used our advanced models to select white dwarfs which are likely to be older than 10 Gyr for followup in 12B. The requested observations will (1) expand the known (small) sample of thick disk/halo white dwarfs by 20 - 30% (2) expand our knowledge of the chemical and kinematic evolution of these Galactic remnants and (3) allow refinement of techniques for identifying such sources in current and future surveys.