Top panel: mass fraction of synthesized nuclei as a function of atomic mass A from our fiducial model that reproduces the late-time gamma-ray emission light curve from SGR 1806–20 (Figure 2). Vertical blue bars (right axis) show the individual percentage contributions of radioactive nuclei to the total gamma-ray energy in the time interval t = 10³–10⁴ s. Bottom panel: synthetic gamma-ray spectra from the fiducial model at three snapshots, t = 1000, 3000, 12,000 s, accounting for Doppler broadening due to the ejecta expansion but excluding extinction effects. For the spectrum at t = 3000 s, we also show with lighter blue lines the intrinsic (i.e., nonbroadened) decay lines, which contribute to the total spectrum. A thick dark gray line shows the bremsstrahlung spectral fit made by S. E. Boggs et al. (2007) in the energy range  ≈ 0.1–2.5 MeV, while a dotted light gray line shows the same fit outside of the measured energy range. The gray shaded area indicates the ±0.7 MeV uncertainty in the fit.