Left upper: HOC⁺ (1–0) (blue line and filled yellow) overlaid with H¹³CO⁺ (1–0) (green line, divided by 2), and HCO⁺ (1–0) (red line, divided by 38). The RMS is 0.30 mK for HOC⁺ (1–0) at a velocity resolution of 29.44 km s⁻¹. The RMS is 0.31 mK for H¹³CO⁺ (1–0) at a velocity resolution of 30.37 km s⁻¹. The RMS is 0.89 mK for HCO⁺ (1–0) at a velocity resolution of 29.54 km s⁻¹. Right upper: HC¹⁸O⁺ (1–0) (filled yellow) and the Gaussian fitting profile (red line). The RMS is 0.27 mK at a velocity resolution of 24.75 km s⁻¹. Left lower: CH₃CCH (5₀–4₀) and c-C₃H₂ (2_1,2–1_0,1) (filled yellow), overlaid with the Gaussian fitting profiles (red for CH₃CCH, blue for c-C₃H₂, and green for the combination of the two components). The RMS is 0.36 mK at a velocity resolution of 24.67 km s⁻¹. Right lower: H42α (filled yellow) and Gaussian fitting profile (red line). The RMS is 0.43 mK at a velocity resolution of 24.60 km s⁻¹.