Upper row: stacked images of all GCs subsamples: left) all 618 GCs; center) 316 red GCs; right) 302 blue GCs. The central circle highlights the 3′′diameter region where most of the flux from the stacked LMXBs is concentrated. The images are produced through a sigma-clipped averaging algorithm with the clipping threshold set at 4σ. Lower row: same as the upper row, for 3 of the 100 samples simulated using random positions near real GCs (see discussion in text).