Distribution of the observed apparent maximum brightness in R-band and the fitted t₂ for all nova candidates. The red and blue points refer to Eq. (3) with t₀ as free parameter and Eq. (4) with t₀ as fixed parameter, respectively. The green points are novae that belong to other classes. The t₂ value is derived from the dm/dt and the observed apparent maximum in the light curves. See the main text for a detailed description.