Star formation rate surface density map of NGC 1097 (Σ_SFR in units of M_⊙ yr⁻¹ pc⁻²). We present the limits of the nuclear disc defined in this work (Table 3; solid black contour) and the ring region from which we extract the representative spectrum in dashed black contour (see illustration in Fig. 2). Additionally, we present the Σ_SFR = 2×10⁶ mask (solid-white countour). The mask is limited to the star-forming ring. Since we are interested in the oldest stars that belong to the nuclear disc, masking the active star-forming regions will not affect our methodology.