We present new observations leading to an improved black hole mass estimate for the Seyfert 1 galaxy NGC 4593 as part of a reverberation-mapping campaign conducted at the MDM Observatory .
Cross-correlation analysis of the H \beta emission-line light curve with the optical continuum light curve reveals an emission-line time delay of \tau _ { cent } = 3.73 \pm 0.75 days .
By combining this time delay with the H \beta line width , we derive a central black hole mass of M _ { BH } = ( 9.8 \pm 2.1 ) \times 10 ^ { 6 } M _ { \odot } , an improvement in precision of a factor of several over past results .