On-axis (θ_v = 0 × θ_c), edge (θ_v = θ_c), and off-axis (θ_v = 3 × θ_c) views of HLE (continuous line) and forward shock (dashed lines) models used in O20 to fit the light curve of GRB 100906A. The light curves are integrated in the energy range 0.5 − 10 keV. HLE model parameters: Γ_c = 160, R₀ = 3 × 10¹⁵ cm and θ_c = 3.3° and θ_E = 4.4°, spectrum: SBPL, α_s = 0.67, β_s = 3.0 and ν_peak = 100 keV, jet structure: Gaussian. Forward shock model parameters: n = 15 cm⁻³, p = 2.1, ϵ_e = 0.03, ϵ_B = 2 × 10⁻², E_K,ISO = 5 × 10⁵³ erg.