Test measurements confirm that the spectral resolution of the instrument is
limited by its spatial resolution : a 
or 
slit, broadened by the diffraction of a 60 cm telescope. The measured spectral
resolution of extended sources confirms the expected resolution.
Fig. 
shows Gaussian fits to laser lines, one measured in the
SW (2.38-12 
m) section, one measured in the LW (12-45.2 m)
section. Down to an approximate 5% level of the
peak, SWS grating spectral profiles
are found to correspond closely to a
Gaussian. However, below this 5% level, the profiles are observed to
become asymmetric and to vary with wavelength. Beyond this, at a
certain fixed wavelength, the profiles below the 5% level are found to
be different for different detector elements.
Fig. shows the FWHM of the spectral resolution of the
SW and LW sections of the instrument vs. wavelength.