Convergence of the SALT zero-phase parameter t₀, as a function of SN phase, separating candidates by their maximum model g measurement. Large, dark grey points are the $t_0-t_0^{\ast }$ differences as a function of time from $t_0^{\ast }$ for candidates in that magnitude bin. The coloured solid line and shaded region in each panel show the median and central 68% region of the candidates in that magnitude bin. The light grey points, median in black and 68% region in grey for the entire sample are shown as in Fig. 6. The auxiliary axes to the left of the main panels are the normalised distribution of differences $t_0-t_0^{\ast }$ in the $t-t_0^{\ast }$ interval [−1, +1]. The black curve (the same in each panel) is for the full sample.