The results of the HC¹⁷O⁺ observed spectrum modelling with LOC are displayed. Left: observed spectrum of the HC¹⁷O⁺ (1−0) (black), the result of a simulation using the original HC¹⁷O⁺ fractional abundance profile at 5 × 10⁵ yr and the original pre-stellar core model (OM; dotted red) and the result of a simulation using the HC¹⁷O⁺ fractional abundance profile at 5 × 10⁵ yr upscaled by a factor of 4 times that of the original pre-stellar core model (AM 1; solid red). Residuals are computed with the adopted model and are shown in the lower panel. The dashed lines represent the 3σ levels. Right: observed spectrum of the HC¹⁷O⁺ (1−0) (black) and the result of a simulation using the HC¹⁷O⁺ fractional abundance profile at 5 × 10⁵ yr upscaled by a factor of 4 and an upscaled velocity profile by 30% (AM 2; solid red). Residuals are computed with the adopted model and are shown in the lower panel. The dashed lines represent the 3σ levels.