Selection of GA transitions observed and fit (see Sect. 6.1). The black histogram and its grey shadow are the observational spectrum, and the red curve is the cumulative LTE fit considering all detected species. The blue curve is the fit of the individual transitions. The horizontal dashed green line indicates the 5σ level, corresponding to ∼1.35 K. Only transitions contributing at ≥5σ are labelled. The plots are sorted by decreasing intensity of the GA transitions (blue line). The upper left corner of each panel indicates the E_UP of the corresponding GA transition. When multiple GA transitions are shown in the same panel, the E_UP values are listed from top to bottom following the left-to-right order of the transitions.