This plot is built from the results of Case A shown in Figs. 6 and 7. Each point in the plot represents a set of parameters accepted by the ABC algorithm as part of the posterior PDF. For each accepted set we plot the Poissonian distance (δ_P) as a function of the inverse of the characteristic timescale (γ parameter) of an assumed decreasing exponential SFH. δ_P is computed using the expression of Eq. (58); the smaller the value of δ_P, the better its agreement with the data. Dotted horizontal line gives the δ_P value around the best fit (δ_P ≈ 16 000) and the solid horizontal line is to emphasise the degeneracy for three different sets of parameters of the model variants (see Table 2). The vertical dashed black lines denote the quantile 0.16 (left) and quantile 0.84 (right) for the distribution of Fig. 3. The vertical red dashed line is for the mode of the γ distribution in Fig. 3. We obtain these results when using as observational data the stars in the Tycho-2 catalogue with visual apparent magnitude V_T < 11. Variant/extinction map combinations are as described in Fig. 4.