Modeling of the 2011 March 30 flare pn light curve with a rotating hotspot. Best-fitting theoretical light curve (dot-dashed line) plotted over the smoothed light curve (solid line, with 1σ error in gray). The non-flaring level is given by the horizontal dashed line. The vertical axis is in observed units, horizontal axis is in seconds. The lower panel gives the residual in units of σ.