  We present Keck II laser guide star adaptive optics observations of the brown
dwarf WISEP J061135.13-041024.0 showing it is a binary with a component
separation of 0.4". This system is one of the six known resolved binaries in
which the magnitude differences between the components show a reversal in sign
between the Y/J band and the H/K bands. Deconvolution of the composite spectrum
results in a best fit binary solution with L9 and T1.5 components. We also
present a preliminary parallax placing the system at a distance of 21.2+/-1.3
pc. Using the distance and resolved magnitudes we are able to place WISEP
J061135.13-041024.0AB on a color-absolute magnitude diagram, showing that this
system contributes to the well-known "J-band bump" and the components'
properties appear similar to other late-type L and early-type T dwarfs. Fitting
our data to a set of cloudy atmosphere models suggests the system has an age >1
Gyr with WISEP J061135.13-041024.0A having an effective temperature (Teff) of
1275-1325 K and mass of 64-65 M_Jup, and WISEP J061135.13-041024.0B having Teff
= 1075-1115 K and mass 40-65 M_Jup.
