LAUSR

We measure the black hole mass and investigate the accretion flow around the local (z = 0.0502) quasar PG 1119+120. Spectroscopic monitoring with Calar Alto provides Hβ lags and linewidths from which we estimate a black hole mass of log (M•/M⊙) = 7.0, uncertain by ∼0.4 dex. High cadence photometric monitoring over two years with the Las Cumbres Observatory provides lightcurves in 7 optical bands suitable for intensive continuum reverberation mapping. We identify variability on two timescales. Slower variations on a 100-day timescale exhibit excess flux and increased lag in the u′ band and are thus attributable to diffuse bound-free continuum emission from the broad line region. Faster variations that we attribute to accretion disc reprocessing lack a u′-band excess and have flux and delay spectra consistent with either τ∝λ4/3, as expected for a temperature structure of T(R)∝R−3/4 for a thin accretion disc, or τ∝λ2 expected for a slim disc. Decomposing the flux into variable (disc) and constant (host galaxy) components, we find the disc SED to be flatter than expected with $f_{\nu } \sim \rm {const}$. Modelling the SED predicts an Eddington ratio of λEdd > 1, where the flat spectrum can be reproduced by a slim disc with little dust extinction or a thin disc which requires more dust extinction. While this accretion is super-Eddington, the geometry is still unclear, however a slim disc is expected due to the high radiation pressure at these accretion rates, and is entirely consistent with our observations.