Plot of the separation index defined in the text for stars in the GC H4 as a function of central distance. Gray crosses denote all red giant stars projected on the sky near the cluster, and our targets are highlighted with black circles. While m_sep = 0.0 means that half of the star light comes from blending neighbors, m_sep = 4.0 and 5.0 means ~2.5% and 1.0% contamination, respectively.