Zoom-in of the region from 9000 Å to 10 500 Å at t_max+377.5 days. Cobalt has its strongest feature at 1.025 μm. Its tentative detection translates to ⁵⁶Ni mass of ≳30 M_⊙, consistent with the light curve modelling. The second strongest cobalt feature is at 9340 Å. Its location is indicated by a fiducial Gaussian centred 9340 Å. Its integrated luminosity is expected to be between 50 and 100% of [Co II] λ 1.025 μm. The absence of [Co II]λ 9340 is not an argument against the discovery of [Co II] λ 1.025 μm (see Sect. 5.2.5 for details). Lines from other elements that could blend with the [Co II] lines are marked. Regions of strong atmospheric absorption are indicated by vertical bars at the top of the figure.