Main characteristics of the 8 possible configurations of the AURELIE spectrometer. The resolving power R / is determined with an element of resolution effectively measured with each grating (FWHM of a thorium line which is between 2.5 and 3 pixels). The recommended wavelength regions for an optimal grating efficiency are marked by a thick line. D is the observed spectral range in Å. The reciprocal linear dispersion is given in Åmm.