Program: GN-2012B-Q-75

The first proposed cold Y dwarfs have been discovered in the mid-infrared by the Wide-field Infrared Survey Explorer (WISE). Our group has started a program to obtain near-infrared photometry in order to characterize this new class of Galactic object, with T_eff <~400K. The 1um colors, Y and J, are sensitive to the properties of the sulfide, chloride and ice condensates that are expected to form at these temperatures, and will constrain new cloudy models being calculated by members of our group. The 1.6um color, H, is sensitive to gravity, or mass, and the near- to mid-infrared color is sensitive to temperature. Hence, while most of the flux from these objects is emitted in the mid-infrared, accurate near-infrared data are crucial for their characterization. We request 5.9 hours to complete the NIRI photometry set for the six Y dwarfs (assuming our 12A Band 3 program, GN-2012A-Q-106, is completed).