Left-hand corner plots: Same as Fig. 4 but for M3D. Here both the young and old solutions are shown, and they are marked with cyan and magenta lines, respectively. Right-hand corner plot: Constraints on the NS mass and orbital inclination angle of M3D, with posterior distributions shown in cyan for the young solution and magenta for the old solution. The derived values for the companion mass, cooling age, effective temperature, NS mass, and orbital inclination for the two solutions are listed in Table 2.