The 2MASS Wide-Field T Dwarf Search. V. Discovery of a T Dwarf via   Methane Imaging
  We present the discovery of a T dwarf, 2M2151-4853, via differential imaging through methane filters. The filters are designed to highlight the strong absorption in the H band, due to methane found in the atmospheres of T dwarfs, and provide a very efficient means of searching for them. Subsequent J and H band spectroscopy confirms 2M2151-4853 as a T dwarf of type T4.5. It has an estimated spectrophotometric distance of 18 +/- 3 pc, and an estimated tangential velocity of v=50 +/- 10 km/s. 
S. C. Ellis (1), C. G. Tinney (1), Adam J. Burgasser (2), J. Davy   Kirkpatrick (3), Michael W. McElwain (4) ((1) AAO, (2) A...