This plot estimates the external field for Virgo and Coma galaxies. Abscissa is the projected distance in Mpc from M 87 and NGC 4874, respectively. Ordinate is the acceleration in units of a₀. The adopted distances for Virgo and Coma are 15 Mpc and 100 Mpc, respectively. The values for Virgo are generated by an extrapolation of the M 87 mass model of McLaughlin (1999). Some G01 galaxies are indicated by their NGC numbers. The values for Coma are generated by using the NFW dark halo of Łokas & Mamon (2003). Small open circles are the 18 T09 galaxies whose projected distances are taken from Godwin et al. (1983). The comparison with Table 1 shows that the EF is small.