Evolution of the volume-filling fraction of neutral gas in the OBELISK volume. The shaded area indicate the cosmic microwave background constraints from Planck, and the data points show various observational constraints (see text for details). While reionization starts at z > 12, the volume is only significantly ionized (Q_H I < 90%) at z₁₀ ∼ 8.68 and reionization finishes around z₉₉ ∼ 5.92, with a midpoint around z₅₀ = 7.53.