Spectrum obtained from a source at the position of Cas A at 1157 keV (black crosses, 2.5 keV energy bins). The spectrum has been fitted by a constant plus a Gaussian that is centered at (1158 ± 3.6) keV and broadened (8.94 ± 1.42) keV (FWHM). The derived expansion velocity of the ⁴⁴Ti ejecta is (2200 ± 400)km s^-1. The measured flux is (3.5 ± 1.2) × 10^-5 ph cm^-2 s^-1, which can be converted to an observable ⁴⁴Ti mass of (2.4 ± 0.9) × 10^-4 M_⊙ at the time of the explosion. The cumulative long-time spectrum (mainly background) is shown as a gray histogram. The laboratory-determined energy of the excited ⁴⁴Ca line is marked with an arrow.