Upper panel: minimisation parameter S computed for different . Lower panel: best fit to the observed spectrum computed for = 0.0005 and 0.00040. Fits with values = 0.01 ad 0.01 are shown only for the evaluation purposes. The arrow at 23 911 Å marks the position of the head of the Δv = 2, v′ = 0 band of the ¹⁴C¹⁶O molecule. Black thick lines mark missed spectral features of telluric spectrum.