M_ϖ vs. Gaia colour G_Bp − G_Rp for the stars with G <  12 divided into three latitude ranges: first row: 30 <  |b|< 90; second row: 10 <  |b|< 30; third row: |b|< 10. The colour-map of the first, second, and third columns shows the logarithm of the star counts in each bin. The first column is Gaia DR2 data and the second column is the most probable model variant from Mor et al. (2018), which has an exponential SFH and whose IMF has α₃ ≈ 3. The third column is for the best-fit model using a non-parametric SFH, whose IMF has α₃ ≈ 2 (this work). The BGM simulations performed for this figure use the Stilism extinction map. In the fourth column we show, for each bin, the difference of star counts MP-S minus Gaia DR2 data. In the fifth column we show, for each bin, the difference of star counts G12NP-S minus Gaia DR2 data. Observational data and simulations are limited here at G <  12 and 10 <  M_ϖ <  −1.