Marginalised posterior distributions for the spectral fit of the afterglow observations of GRB 190114C at t_obs = 90 s. The total (black) is subdivided between the slow (blue) and fast (red) cooling cases. The first row shows the four free parameters explored in this MCMC analysis (Γ, ϵ_e/ϵ_B, B and γ_m). In the second row, we show some derived quantities: ${\widehat{\gamma }}_{\mathrm{m}}/{\gamma }_{\mathrm{m}}$, γ_c/γ_m and B/Γ³. The bottom right panel shows the distribution of the radiative regimes found in the posterior sample (see Appendix B for their description). The best-fit model for each radiative regime is shown in Fig. 3.