Evolution of the 67.5−189 keV band during revolutions 1380-81, 1382-83, and 1384-86 as obtained by IBIS/ISGRI using the method described in Isern et al. (2013). The dotted line represents the flux that would be provided by the free disintegration of ⁵⁶Ni. Dashed lines represent the light curves obtained by convolving models DETO, SC3F, SC1F, W7, and DDTe (from top to down) with the instrument response. Solid lines represent, from top to down, the 3Dbball with plumes of 0.08 and 0.04 M_⊙ of ⁵⁶Ni, and the DDT1p4 models after convolution. The properties of these models are displayed in Appendix A.1.