Effective exposure time required to achieve a 5σ detection of the 478 keV line determined using the observed flux during revolution 1368 and the estimated explosion time of the nova. Assuming a constant flux over time for the 478 keV feature (red curve) and a decaying flux following the time decay of ⁷Be (red dashed curve), we find that an uninterrupted exposure time of 440 ks would be necessary. However, due to instrumental constraints (see text), this corresponds to an effective exposure time of approximately 780 ks to reach a 5σ detection.