Left panel: composite image (adapted from Fig. 6 in Milisavljevic et al. 2024), combining the NuSTAR ⁴⁴Ti map (blue), a Chandra Fe-K map (energy ∼6.7 keV; green) with the unshocked ejecta map derived from JWST observations (red). The center of expansion (COE; Thorstensen et al. 2001) and the neutron star are indicated by white and black circles, respectively. Right panel: composite image based on model W15-IIb-sh-HD+dec-hr (see Table 1), showing 3D volumetric renderings of the distributions of ⁴⁴Ti (blue), shocked ⁵⁶Fe (green), and unshocked ¹⁶O (red). The center of explosion is marked with a white circle. While the model-derived image illustrates the overall geometry of the ejecta, it is not intended to replicate the exact observational appearance.