Left-hand panel: light curves of transit events of WASP-80 b observed in Gunn r with the Euler telescope (Triaud et al. 2013), in Bessell I with the Danish telescope (this work) and in z with TRAPPIST (Triaud et al. 2013). The light curves are ordered according to central wavelength of the filter used. The jktebop best fits are shown as solid lines for each optical data set. Right-hand panel: residuals of each fit.