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Space Telescope Science Institute
Brown Dwarf and Superplanet Detection Using Differential Methane-Band Imaging

Edward Rosenthal, Mark A. Gurwell, Paul T.P. Ho, Jonathan P. Williams
Harvard-Smithsonian Center for Astrophysics, Cambridge MA

Differential methane-band imaging (Smith 1987, PASP, 99, 1344; Rosenthal et al. 1996, Nature, in press) is an important tool for brown dwarf and superplanet detection. Subtraction of a near-infrared methane-band image from an image taken in the adjacent brown dwarf continuum readily reveals Gl 229B-like brown dwarfs, as they are seen to modulate in flux while all other objects, including primary stars, null out. We present differential images of the Gl 229B system taken at the NASA Infrared Telescope Facility (IRTF) in August, 1996, as a demonstration of the power of this technique. Preliminary results for 65 G, K, and M stars imaged at the IRTF will be presented. We will discuss future observing strategies using the IRTF, Keck, HST, and other telescopes.