Velocity plots for H I Ly α absorption for the sightlines passing the outer environment of the NGC 1052 group (lower two panels). OGrM absorbers are marked in dark orange. The expected radial velocity range for OGrM absorption is indicated with the gray-shaded area (see Sect. 2.3). The upper panel shows the velocity distribution for group member galaxies (green histogram) and for all galaxies in the group’s field (gray histogram).