Fast-mode Mach number M_fm as a function of time calculated using Eq. (7) for γ = 4/3 (dashed blue curve) and γ = 5/3 (dashed red curve). The shaded green bands represent M_fm values computed using MAS with the given correction factors, as the angle θ_Bn between the wave vector and the magnetic field vector varies from 0° to 25°. The plot also shows the temporal evolution of the shock standoff distance ΔR, the effective radius of the flux rope's curvature R_c, and the ratio ΔR/R_c.