Table 2.1 contains the current grating inventory and dispersion characteristics as used in the B&C Spectrograph. Note that these parameters were computed assuming a 1200 pixel CCD with 15m pixels. Useful spectral range is limited by the smaller of the ``Spec Coverage'' or ``Free Spec Range'' (separation between orders) of the grating. Similarly, resolution for the high-dispersion gratings will be poorer than that indicated because of inadequate sampling of the slit at the detector. Absolute grating efficiencies are shown in Figures 2.1-2.3.
Table: B & C Spectrograph Grating Inventory. Parameters computed assuming 2 slit and 1200 CCD with 15 m pixels. At tilt angles , the beam from the collimator is progressively vignetted by the undersized grating (see Figure 2.5). The above calculations used camera-collimator angle and camera focal length in. Note also that one will be limited by the smaller of either the spectral coverage or free spectral range.
Figure 2.1: Efficiencies for gratings 300(1)/6693Å, 300(2)/3347Å, 600(1)/6681Å, and 600(2)/3341Å.
Figure 2.2: Efficiencies for gratings 300(1)/3761Å, 600(1)/4458Å, 400(1)/7506Å, 400(2)/3753Å, 1200(1)/7847Å, and 1200(2)/3924Å.
Figure 2.3: Efficiencies for 832 g/mm gratings, for unpolarized light as well as light polarized perpendicular and parallel to the grating.