  We study the angular resolution of the gravitational wave detector LISA and
show that numerical relativity can drastically improve the accuracy of position
location for coalescing Super Massive Black Hole (SMBH) binaries. For systems
with total redshifted mass above $10^7 M_{\odot}$, LISA will mainly see the
merger and ring-down of the gravitational wave (GW) signal, which can now be
computed numerically using the full Einstein equations. Using numerical
waveforms that also include about ten GW cycles of inspiral, we improve
inspiral-only position estimates by an order of magnitude. We show that LISA
localizes half of all such systems at $z=1$ to better than 3 arcminutes and the
best 20% to within one arcminute. This will give excellent prospects for
identifying the host galaxy.
