Zoomed-in view around the peak region of the KMT-2021-BLG-1547 light curve. The lower three panels show the residuals from the 2L2S (wide), 3L1S (wide), and 2L1S (wide) models. The dotted and solid curves drawn over the data points in the top panel are the models of the 2L1S and 2L2S solutions, respectively. The arrow labeled “t_bump” indicates the region that leaves a bump in the residual from the 2L1S model. The two insets in the top panel show the lens-system configurations of the 2L1S and 3L1S models. In each inset, the red figures are the caustics, and the line with an arrow represents the source trajectory.