Rotational temperature and production rate analyses for water and organic trace gases in 21P/Giacobini–Zinner. Panels (a), (c), (d), and (e) show the excitation analysis for water and HCN, both in settings L1-c (on September 8), for CO in setting M1 (on 2018 August 1), and for C₂H₆ in setting Lp1 (on 2018 September 9). The comparison of the water rotational temperatures, retrieved on September 8, derived from the slope analysis method (purple) and from the correlation analysis method (light green) is reported in panel (b).