Constraints on the parameters of a Gaussian BNS mass distribution model. Filled contours show the posterior probability density on the μ_m (mean) and σ_m (standard deviation) parameters of a Gaussian mass distribution model (assuming random pairing) obtained using f_j = f_j, GW, i.e. the constraint based on the association of GW170817 and GRB170817A (Sect. 2). Empty contours show the corresponding result for f_j  =  f_j, tot, i.e. the constraint based on the relative SGRB and BNS local rate densities (Sect. 2.2). The white star marks parameter values (μ_m, σ_m)  =  (1.33, 0.09) M_⊙, representative of the main peak of the observed Galactic BNS mass distribution (Özel & Freire 2016).