Edge detection in NGC 3486. Upper row: stellar mass surface density map in Cartesian and polar coordinates (left and central panels) and polar map of its second derivative (right). Bottom row: radial profile of averaged stellar mass surface density as a function of radius (central panel) along with its second derivative (right panel). A polynomial fit to the data and its second derivative are also shown (blue). In all panels shaded regions indicate measurement uncertainties. The outer boundary, R_edge is indicated in all panels by a dashed black line. Σ_*(R_edge) is shown as a horizontal red line in the bottom central panel. Yellow dots in the upper panels mark R_edge, θ.