Example of group multiplicity. We plot the RA-Dec distribution of three galaxy groups which share at least one MaNGA galaxy with one of the other of the three groups. There are two large groups, one indicated with a blue marker, and the other with a black empty circle. There is also a small group indicated with a red marker (lower right). There is one MaNGA galaxy that belongs to all three groups. The group selector algorithm has selected the group of galaxies indicated with the black empty marker. The mean redshift of these galaxies is 0.028.