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We present 107 new epochs of optical monitoring data for the four brightestimages of the gravitational lens SDSS J1004+4112 observed between October 2006and June 2007. Combining this data with the previously obtained light curves,we determine the time delays between images A, B and C. We confirm our previousmeasurement finding that A leads B by dt_BA=40.6+-1.8 days, and find that imageC leads image A by dt_CA=821.6+-2.1 days. The lower limit on the remainingdelay is that image D lags image A by dt_AD>1250 days. Based on themicrolensing of images A and B we estimate that the accretion disk size at arest wavelength of 2300 angstrom is 10^{14.8+-0.3} cm for a disk inclination ofcos{i}=1/2, which is consistent with the microlensing disk size-black hole masscorrelation function given our estimate of the black hole mass from the MgIIline width of logM_BH/M_sun=8.44+-0.14. The long delays allow us to fill in theseasonal gaps and assemble a continuous, densely sampled light curve spanning5.7 years whose variability implies a structure function with a logarithmicslope of gamma = 0.35+-0.02. As C is the leading image, sharp features in the Clight curve can be intensively studied 2.3 years later in the A/B pair,potentially allowing detailed reverberation mapping studies of a quasar atminimal cost.

The Rewards of Patience: An 822 Day Time Delay in the Gravitational Lens SDSS J1004+4112