Top: azimuthally averaged g-band radial surface brightness profiles of M 101 in Merritt et al. (2016; solid line with a shaded region) and in this study (red dots with error bars), reproduced from the image data provided by the DNGS. Two profiles agree well. A weak break in the brightness profile is detected at R ∼ 24 kpc (arrow). Bottom: difference between the two profiles, in the sense that our profile is ∼0.08 mag fainter than that of Merritt et al. (2016).