Upper panels: evolution of the neutral temperature and optical depth of the OH line at 1835 GHz along the shock layer (versus a distance parameter along the direction of propagation of the shock) for a J-type model with n_H = 10⁵ cm^-3, b = 0.1, and ν_s = 30 km s^-1 (left) and a C-type model with n_H = 10⁶ cm^-3, b = 1, and ν_s = 30 km s^-1 (right). Lower left panel: variation in the factor μ·(1−e^{− τ/μ2})/(1−e^{− τ}) with the optical depth for six inclination angles. Lower right panel: variation in the ratio [^∫Tdν (μ)]/[^∫Tdν (μ = 1)] with the inclination angle for the two shock models considered.