Average [C II] spectrum towards the Veil shell without OMC1 and ISF. The inlaid panel shows the residual of the spectrum, in the systemic velocity of the [¹³C II] F = 2 − 1 line, after subtracting the [¹²C II] fit. The [¹²C II] line can be fitted by two Gaussians with T_P ≃ 11.2 ± 0.3 K, v_P ≃ 8.8 ± 0.1 km s⁻¹, Δv_FWHM ≃ 5.0 ± 0.1 km s⁻¹ and T_P≃ 2.3 ± 0.1 K, v_P ≃ 4.0 ± 0.4 km s⁻¹, Δv_FWHM ≃ 9.3 ± 0.5 km s⁻¹; the [¹³C II] F = 2 − 1 component is fitted by a Gaussian with T_P ≃ 0.11 ± 0.02 K, v_P ≃ 8.2 ± 0.3 km s⁻¹, Δv_FWHM ≃ 2.1 ± 0.6 km s⁻¹. The main line could also be fitted with three Gaussian components, but we compare the respective combined peak temperatures of the [¹²C II] and [¹³C II] line for a first-order estimate of the excitation conditions.