Best fit of the line flux ratios of the detected sodium emission lines and the C₂ band head at 5165 Å in the spectra of comet NEOWISE. Red data refer to Bischoff & Mugrauer (2021), and blue data refer to this work. The star represents the ratio between the D2 line at 5890 Å and the C₂ line at 5165 Å. The circle represents the ratio between the D1 line at 5896 Å and the C₂ line at 5165 Å. Best-fit equations and the reduced chi-square values, , are reported.