  In this Letter, we report on the gravitational wave signal computed in the
context of an $ab$ $initio$, three-dimensional simulation of a core collapse
supernova explosion, beginning with a 15M$_\odot$ star and using
state-of-the-art weak interactions. The simulation was performed with our
neutrino hydrodynamics code Chimera. We discuss the potential for detection of
our predicted gravitational signal by the current generation of gravitational
wave detectors.
