H I gas distribution of NGC 4523. For each resolution, we show the lowest reliable contour (3σ over a line width of 25 km s⁻¹). The contours are overlaid on an r-band image downloaded from the Legacy Survey database. The contour levels and resolutions are listed in the legend at the bottom, and the resolutions are shown in the top left corner. At the highest resolution of 15″, we also show an additional contour at a 5× higher column density than the lowest reliable contour. These H I images reach column densities a factor of $\sim \sqrt{2}$ better than those reached during the pilot observations published in Boselli et al. (2023c).