Residual VLT/FORS1 V-band image with respect to the MSM for NGC 3311 and NGC 3309. The white ellipse indicates the extended halo off-centered towards the NE of the bright inner regions of NGC 3311 (black). The angular extent of this envelope as seen from the center of NGC 3311 is consistent with the opening angle of the additional light as shown by Figs. 7 and 8. The most noticeable substructure on top of the extended envelope NE of NGC 3311 is the tidal stream associated with the dwarf galaxy HCC 026. Its NW part is indicated on the image with the blue dashed polygon. At larger radii, and at fainter surface brightness levels, we see a thicker tail around HCC 007; the luminosity in this tail is computed in the areas limited by the white polygons (see Sect. 4.3). The two small objects near the center of the NE polygon appear to be connected by a further small stream (see also Fig. 9). The FoV is . Color levels are labeled with the corresponding surface brightness values. This image shows that in the region south of HCC 007 the background is flat, with a systematic E-W gradient across the image at less than  ~ 10 ADU. The white, green, and blue lines from the center of NGC 3309 indicate the PAs at  = 190°, 230°, and 320°, respectively; see extracted profiles in Fig. 12.