Example of a spectral energy distribution for observed GRBs with (dashed lines) and without (solid lines) extinction, assuming the SMC extinction law. We show the afterglow flux F(mJy) as a function of frequency ν (Hz) for typical parameters: isotropic kinetic energy E_iso = 10⁵⁴ erg, electron spectral index p = 2.5, plasma parameters ϵ_e = 0.1, ϵ_B = 0.01, half-opening angle jet θ_j = 0.1, and interstellar medium density n = 1 cm^-3. The black line represents θ_obs = 0, t = 0.5 days, blue line, θ_obs = 0, t = 5 days, red line, θ_obs = 0.05, t = 0.5 days, and orange line, θ_obs = 0.05, t = 5 days.