Distribution in the Y_E - H_E versus I_E - H_E plane of sources in the NGC 6822 photometric catalog after removal of bright I_E ≲ 20 MW disk stars in Gaia DR3. In the top panel, the PARSEC stellar isochrones (Bressan et al. 2012; Marigo et al. 2017) in the Euclid bands are superimposed in red for different ages (from 10 Myr to 10 Gyr) and metallicities of Z ≲ 0.006 (about one-third solar); the TRILEGAL Galaxy model is shown in blue. Giant stars in NGC 6822 and dwarf stars in the MW overlap at I_E - H_E ≲ 1, while the two populations diverge at redder colors. In the bottom panel, we denote the location of Galactic M dwarf stars, AGB stars in NGC 6822, background compact red galaxies, and residual spurious detections. The dashed orange polygon outlines our final selection, which provides a reasonable compromise between the need to retain the largest possible number of stars belonging to NGC 6822, while removing Galactic M dwarfs, compact red galaxies, and residual spurious detections (see text for details).