Initial value parameter space of γ_max and ϵ_e for E₀ = 10⁵⁴ erg, Γ₀ = 400,n₀ = 1  part/cm³,ϵ_B = 0.001 and p = 2.3. The numerical factors chosen here are A = 8,b = 0.001 (see text for their definition). Dotted lines correspond to the constraining relation (9), solid lines to (23) and the dashed line sets the boundary of the striped area, which is not permitted because it it leads to γ_max = γ_min,0. The horizontal zones labeled by k = 2 and k = 3 correspond to transition times lying in the time intervals 10²–10³ s and 10³–10⁴ s, respectively. The “coordinates” (ϵ_e,γ_max) of the points 1 to 4 marked on the plot are  { (0.005,1.41 × 10⁴),  (0.01,1.41 × 10⁴),  (0.01,2.24 × 10⁴),  (0.025,2.24 × 10⁴) } , respectively . The corresponding X-ray and optical light curves of the points are presented below in Figs. 6 and 8.