Grayscale Cousins/I image of UG101 and UG101b, generated from the MUSE datacube. The center of UG101 is marked with a magenta cross. The thin cyan line represents the UG101 main body, derived as described in Sect. 3.6.2. The dashed blue ellipse indicates the location where tidal forces from UG101b reach ∼15% of the centripetal force from the main galaxy (R_tid). The dotted yellow ellipse shows this value now considering the net tidal force from the host cluster, A3558. For reference, the shaded green region marks the galactocentric distance of 2R_e ± σ_Re.