Left panel: g magnitude vs. concentration index (Δg₆₋₁₂ ≡ g_6pix − g_12pix) for the full ugi matched sample (in gray) in NGC 3115. Spectroscopic confirmed GCs are shown with green filled circles (from Arnold et al. 2011)and photometric confirmed GCs from ACS are shown with empty green circles (from Jennings et al. 2014). Blue circles indicate UCDs from Jennings et al. (2014). Red dots indicate confirmed stars from both the spectroscopic and ACS studies cited. The gray hatched area shows the regions of sources rejected based on the concentration index selection. The horizontal dotted line indicates the bright magnitude cut. Right panel: as left panel, except that GC candidates before color–color selection are shown with orange empty circles.