Constraints on the isotropic kinetic energy of the blastwave and the luminosity distance of the source for the on-axis GRB external shock model. The solid and dotted lines represent for the upper limits of E_iso with the ISM number density n₀ = 1 cm⁻³ and 0.1 cm⁻³, respectively. The dashed lines are upper limits for the wind model with ﹩{A}_{\star }=0.1﹩. Besides, we set microphysics shock parameters to be ε_e = 0.1, ε_B = 0.01, and electron index p = 2.3.