Optical/UV SEDs evolution along the outburst. The reddening corrected observed fluxes are plotted with different colours: V-Johnson in red, UVOT-b in yellow, UVOT-u in green, UVOT-uw1 in blue, UVOT-um2 in navy blue, and UVOT-uw2 in purple. Error bars are plotted in gray. Best fitted model predictions are plotted for comparison (black solid lines). The pink dotted lines represent the modelled contribution by the extra emission from heating the surface of the companion star. The brown dashed lines correspond to the contribution from an irradiated accretion disk with the value of R_out providing the best fit.