2016ApJ...830..149F

We present eight monitoring seasons of the four brightest images of the gravitational lens SDSS J1004+4112 observed between 2003 December and 2010 October. Using measured time delays for the images A, B, and C and the model predicted time delay for image D we have removed the intrinsic quasar variability, finding microlensing events of about 0.5 and 0.7 mag of amplitude in the images C and D. From the statistics of microlensing amplitudes in images A, C, and D, we have inferred the half-light radius (at λ_rest=2407 \mathringA) for the accretion disk using two different methods, R_1/2=8.7_–5.5^+18.5\sqrtM/0.3M_☉ (histogram product) and R_1/2=4.2_–2.2^+3.2\sqrtM/0.3M_☉ lt-days (χ²). The results are in agreement within uncertainties with the size predicted from the black hole mass in SDSS J1004+4112 using thin disk theory.