  With the goal of bringing theory, particularly numerical relativity, to bear
on an astrophysical problem of critical interest to gravitational wave
observers we introduce a model for coalescence radiation from binary black hole
systems. We build our model using the "Lazarus approach", a technique that
bridges far and close limit approaches with full numerical relativity to solve
Einstein equations applied in the truly nonlinear dynamical regime. We
specifically study the post-orbital radiation from a system of equal-mass
non-spinning black holes, deriving waveforms which indicate strongly circularly
polarized radiation of roughly 3% of the system's total energy and 12% of its
total angular momentum in just a few cycles. Supporting this result we first
establish the reliability of the late-time part of our model, including the
numerical relativity and close-limit components, with a thorough study of
waveforms from a sequence of black hole configurations varying from previously
treated head-on collisions to representative target for ``ISCO'' data
corresponding to the end of the inspiral period. We then complete our model
with a simple treatment for the early part of the spacetime based on a standard
family of initial data for binary black holes in circular orbit. A detailed
analysis shows strong robustness in the results as the initial separation of
the black holes is increased from 5.0 to 7.8M supporting our waveforms as a
suitable basic description of the astrophysical radiation from this system.
Finally, a simple fitting of the plunge waveforms is introduced as a first
attempt to facilitate the task of analyzing data from gravitational wave
detectors.
