Distribution in the (RA, Dec, z) space of the galaxies with M_∗ > 10^10.3 M_⊙ and the r-band < 27.5 mag placed within the sky-localization area constrained by SKA PTA. Top panel: Distribution of the galaxies when no probability selection is performed. N₁₀₀ indicates the total number of these galaxies. Middle panel: Same as top panel but when presenting only the galaxies that contribute to the 90% probability of being the true host (see Section 5). The size of the circle is proportional to the probability. Lower panel: Right ascension and declination plane. The gray (colored) points correspond to all the galaxies in the N₁₀₀ (N₉₀) sample. The color encodes the photometric color i  −  z.