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The Grating Module and Gratings

  The Grating Module holds large gratings, such as the 206 by 406 mm echelle (grating 316@63.4), one at a time. Grating angle is remotely adjusted and set by this unit.

The parameters for the available gratings are listed in Table 4.

  
Table 4: List of Bench Spectrograph gratings.

Efficiency curves for the Bench Spectrograph gratings are displayed in Figure 5.

  
Figure 5: Blaze efficiency curves for gratings 316@7.0, 400@4.2, 600@13.9, 860@30.9, and 1200@28.7.

Note that the curves for gratings 316@7.0, 600@13.9, 860@30.9, and 1200@28.7 are taken from the RC gratings of similar characteristics and for a camera-collimator angle of 45 degrees. The 400@4.2 curve was measured with the actual grating at Milton-Roy for an angle of 30 degrees.