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 15
m 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.