IGC space–time diagram (not in scale) illustrates the relativistic motion of Episode 2 (Γ ≈ 500, thick line) and the non-relativistic Episode 1 (Γ ≈ 1) and Episode 3 (Γ ≈ 2). Emissions from different radii, R₁ (~ 10¹³ cm) and R₂ (~ 10¹⁶–10¹⁷ cm), contribute to the transition point (E). Clearly, the X-ray luminosity originates in the SN remnant or in the newly-born BH, but not in the GRB.