The solid red line represents the HIFI data, the dashed green, short-dashed blue, dotted purple, dashed-dotted light-blue and short-dashed-dotted brown lines represent, respectively, models with abundances relatively to H₂ of: (4, 2, 1.2, 0.4, 0.2) × 10^-6 for for ortho-HO; (1.2, 0.8, 0.4, 0.2, 0.12) × 10^-4 for ortho-HO; (8, 4, 2, 1.2, 0.4) × 10^-7 for para-HO; and (8, 4, 2, 1.2, 0.4) × 10⁶ for para-HO. We adopted a value of 0.7 km s^-1 for the turbulence velocity in these calculations. The adopted value for the υ_LSR of 40.4 km s^-1 was subtracted from the observed lines.