The modelled time dependence of the Kα luminosity of C1 cloud (green line) and the data points from Ryu et al. (2013; filled squares) with measurement error. Model parameters: accretion model as in Fig. 4 (right panel) and Fig. 5 (right panel), R_cloud = 2.6 pc. Despite so few data points, it is important that the overall normalization of the flux comes out consistent with the model and does not require further tuning of the model parameters.