Cooling curves modelling the evolution of MXB 1659 − 29, along with the error bands on the models. The post-outburst I and post-outburst II evolution data points are shown in black and green and the modelled cooling curves are shown in blue and red, respectively. Panel a: Model A for which all parameters were free to vary. Panel b: Model B for which the y_light after the end of the two outbursts was assumed to be the same (see also Fig. 2).