Core radius R_c distribution of the 17,000 sources detected in the Swift GRB fields as a function of the S/N. As in Figure 7 the triangles with error bars show the mean size of the point sources and the standard deviation about the mean. The line shows the ﹩3\sigma ﹩ size cut used to separate point sources (solid line) from extended sources (open squares). The upper and right histograms show the S/N and R_c histograms for point sources (blue) and extended sources (red).