Diagnostic maps of galaxy 543376 in the TNG50 simulation. Top row: H I column density map down to a depth of 10¹⁶ cm⁻² (left), stellar surface density map overlaid with H I contours (middle), H I metallicity map overlaid with the vector velocity field (right). Central and bottom rows: Moment maps for the HR (central) and LR (bottom) mock H I data, derived with SoFiA. The main galaxy properties are listed in the leftmost panel of the central row. The iso-contours in the N_HI maps are drawn at levels of 10¹⁶, 10¹⁷ (in grey, top panel alone), 10¹⁸ (in blue, top and bottom panels), 10¹⁹, 10²⁰, 10^20.5, and 10²¹ cm⁻² (in black, all panels), with the iso-contour at 10²⁰ cm⁻² highlighted with a thicker line. In the moment-1 maps, the contour at the systemic velocity is shown by a black line, and consecutive contours are spaced by 25 km s⁻¹. The beam sizes are shown as red ellipses in the bottom right corner of the moment-0 maps. The dashed grey iso-contours in the top left panel trace the surface density distribution of the dark matter halo.