Example curves of growth for two galaxies, one bright with a large angular size (NGC 4564, left), the other faint with a small angular size (IC 271, right). Black points in the main panels show the total magnitudes enclosed within each radius (bin width 2″). The inset panels show the local gradients in the outskirts of the curves of growth. Red dashed lines show fits to the linear parts of these gradients chosen by eye; the y-intercepts of these red lines are the asymptotic magnitudes. Gray shaded regions show the 1σ (dark gray) and 2σ (light gray) perturbations to the curves of growth from adjusting the sky subtraction (see Sect. 3.3).