Modified MHD (M²HD) maps. The left panel presents the idealised M²HD when comparing a set of elliptical isophotes against a particular ellipse with P.A. = 72° and b/a = 0.84. The middle panel shows the same comparison but using the mask applied in this paper, which introduces some uncertainty. The right panel instead shows the comparison between the set of ellipses and the real (masked) isophote at the edge of the galaxy. All the panels compare isophotes at 19 arcsec, i.e. right before the location of the edge radius of AGC 114905 at about 20 arcsec. In all the panels, the grey cross represents the minimum M²HD value. For the data, the global minimum of the map (white cross) is consistent within 2σ with the estimates of P.A. and b/a derived through isophotal fitting (see Sect. 3). We note that the first two panels have the same colorbar, but the last panel shows a narrower range to better appreciate the structure of the map.