Normalized intensity profiles of various volatiles for September 18, 2014. The error bars represent the ion statistical counting uncertainty, which is calculated as (n is the number of ions detected), and in some cases, they are smaller than the symbol used (e.g., H₂O). Vertical lines correspond to H₂O maxima. The shaded regions correspond to the CO₂, C₂H₆, and CO maxima independent of H₂O (see text). Bottom panel: Sub-spacecraft longitude and latitude as a function of time (UT). Data gaps are due to reaction wheel offloading. The distance of Rosetta from the comet nucleus was 28.6 km, and the heliocentric distance on this date was 3.34 AU.