Behaviour of the FWHM (left panel) and the resolving power R (right panel) of the G stars of theIRTF spectral library (grey lines) as a function of wavelength. In both panels, the black points represent the mean values for those effective wavelengths and the blue lines mark the mean dispersion. In the left panel, the red line corresponds to a liner relation of the mean FWHM for each wavelength. In the right panel, the red line is a linear relation of the mean R with effective wavelength.