  We report the discovery of an isolated brown dwarf with similar properties to
the binary object Gliese 229B and to the newly discovered field brown dwarf
SDSS 1624+00. Although exhibiting similar colors, its magnitude of ~20.5 is
about 6 and 5 magnitudes fainter than Gliese 229B and SDSS 1624+00
respectively. This is the third methane brown dwarf reported to date, the
second isolated one in the field and by far the most distant at ~ 100 pc. Its
IR spectrum, although at low S/N given the faintness of the object, is
remarkably similar to those of the 2 other methane brown dwarfs.
