Accretion Disk Size Measurement and Time Delays in the Lensed Quasar WFI 2033–4723

We present 13 seasons of R-band photometry of the quadruply lensed quasar WFI 2033–4723 from the 1.3 m SMARTS telescope at CTIO and the 1.2 m Euler Swiss Telescope at La Silla, in which we detect microlensing variability of ∼0.2 mag on a timescale of ∼6 years. Using a Bayesian Monte Carlo technique, we analyze the microlensing signal to obtain a measurement of the size of this system’s accretion disk of at λrest = 2481 Å, assuming a 60° inclination angle. We confirm previous measurements of the BC and AB time delays, and we obtain a tentative measurement of the delay between the closely spaced A1 and A2 images of days. We conclude with an update to the Quasar Accretion Disk Size–Black Hole Mass Relation, in which we confirm that the accretion disk size predictions from simple thin disk theory are too small.