Average on-nucleus (offset 1.7′′) spectrum of the CO(2–1) line at 230.538 GHz obtained with the IRAM 30 m telescope on 24.80 January 2018. The vertical scale is the main beam brightness temperature and the horizontalscale is the Doppler velocity in the comet rest frame. The simulated profile with Q_CO = 5 × 10²⁸ molec s⁻¹ in a 0–60° cone at v_exp = 0.56 km s⁻¹ and Q_CO = 5.5 × 10²⁸ molec s⁻¹ in a 60–120° cone at v_exp = 0.50 km s⁻¹ is superimposed in green dotted line.