Procedure for isolating gas emission features from the observed spectrum, (a) Unbinned spectra of K2 (orange) and 67P/Churyumov-Gerasimenko (green, from Opitom et al. 2020) whose flux and slope are adjusted to those of K2. (b) Flux residuals after subtracting the adjusted 67P spectrum from the K2. Four emission features are highlighted by thick red lines whose flux and underlying continuum images are given in Fig. A.2. Although C₂(1,0) at ~5500 Å is also marginally discernible, a flux map was not created for it in this study, due to its large uncertainty following continuum subtraction.