The Swift UVOT light curve of Ark 120 showing the corrected count rates in the U (red) and UVM2 (blue) bands (adapted from Lobban et al. 2018). Each point corresponds to a single image observation. The 0.3–10 keV XRT light curve (black) is overlaid with an additional y-axis scale. The lower and upper grey shaded areas correspond to the XRT count rates at the 2013 and 2014 XMM-Newton 0.3–10 keV fluxes, respectively. The horizontal dashed lines correspond to the mean flux for each dataset.