Unsharp-masked image of HCG 86 with gaussian smoothing (radius = 4 pixels). It results from the ratio of the VST g-band image and its FMEDIAN smoothed version, using a smoothing box of 50 × 50 pixels. The colour bar indicates the intensity values of the ratio. The image shows an extended envelope of diffuse light associated with the group and symmetrically distributed around the galaxies. The two red arrows indicate the faint low-surface brightness features: the bridge (between HCG 86C and the group) and the filamentary structure at S-E.