Mock images of 200 ks HUBS exposure for J1214+2712. Left: counts map of the 0.1–2.0 band; Middle: O VIII narrowband (0.553–0.559 keV) counts map; Right: O VIII narrowband count map with point sources masked and filled and Gaussian filter applied. Solid and dashed circles represent R₅₀₀ and R_vir respectively for modeled galaxy clusters (green for the three clusters in the 1eRASS-SC J1214+2712 system, and yellow for the background cluster), cyan circles represent point sources, and the white dashed box in each panel represents the HUB FoV.