Illustration of the structures present in the northwestern region of HCG16. Upper left panel: color-composed image using the g, r, and z optical bands from DECaLS. Lower left panel: pseudo zenith view (RA vs. H I velocity) of the H I emission higher than 3σ_rms. Integrated moment-zero and first moment maps as well as detailed information about these data and maps for the whole group can be found in Jones et al. (2019). The dashed blue line in both left panels shows the trajectory of the H I tail, the end of which coincides with the diffuse object detected in the optical. We note that the progenitor of HCG 16-LSB1 is most likely HCG 16c and not the apparently closest galaxy (in projection), HCG 16a. Right panels: zoom-in of the object and its fitting using optical bands through a Sérsic model.