Impact of Merger/Ringdown on SMBHB Parameter Estimation with LISA

The Laser Interferometer Space Antenna (LISA) will measure gravitational waves from the inspiral and merger of supermassive black hole bina ries (SMBHBs) at high redshift with large signal to noise. These meas urements will allow extraction of the SMBHB parameters (component mas ses, spins, binary orbital parameters, sky location, and distance) wi th exquisite accuracy. Here we present a study of the impact on measu red parameter precision from the inclusion of accurate waveforms for the merger/ringdown portion of the signal. we focus specifically on s ky-position and luminosity distance, the most important parameters fo r constraining searches for potential electromagnetic counterparts to SMBHB merger events.