Redshift distribution of the sky-localization uncertainty (given as 90% credible region) for three detector configurations: ET, ET+CE and ET+2CE. The absolute numbers are relative to one year of observation and assuming a duty cycle of 0.85 as described in the text. Plots on the right show BNS systems with a viewing angle 0 < θ_v < 15°. (a) ET, all angles. (b) ET, θ_v < 15°. (c) ET+CE, all angles. (d) ET+CE, θ_v < 15°. (e) ET+2CE, all angles. (f) ET+2CE, θ_v < 15°.