Upper panels: Probability distribution function of the u  −  g, g  −  r, r  −  i, and i  −  z colors for the galaxies within the sky-localization area (N₁₀₀, green), the galaxies within the sky-localization area contributing to the 90% probability of being the true host (N₉₀, blue), and the true host (Host, red). Lower panel: Cumulative distribution function of the u  −  g, g  −  r, r  −  i, and i  −  z colors for N₁₀₀, N₉₀, and true host. In all the plots, the distributions correspond to the galaxies associated with CGWs whose S/N < 25.