Example mock observation from the TNG300-1 simulation. A 500 kpc scale bar is shown in each panel. Left: Simulated aperture mass map (S/N) of FOF halo 142, with R_200c ∼ 750kpc, incorporating shape noise consistent with observational weak lensing data. For visualization, the maps are Gaussian-smoothed with a kernel scale of ∼60 kpc; this smoothing is applied for display purposes only. Right: Surface mass density map (dark matter + gas) in units of log M_⊙/pixel. The positions of the central and the most massive satellite subhalos are marked for reference.