Next: The CCD - Charge Coupled Device
Previous: Filters and the Shutter

3.5 Grating Data

Table 3 lists the gratings available.

  
Table 3: Available Gratings

Gratings 32, 58, 35, 47, and 36 are often used in second order, while 56 has been used in both second and third orders. Grating no. 400 is silver coated for increased efficiency in the red. Efficiency curves for the gratings are reproduced in Figures 7a, b, c, and d. The 1200 line grating can not be used redward of about 8000Å because of mechanical limitations. Note that two copies exist of some rulings.

Since the CCD is sensitive over such a wide wavelength range, the use of order separating filters is imperative. Copper sulfate and a wide variety of Schott glasses are available.

The tilt of the different gratings are listed in the grating tilt Table 4. The tilt for zeroth order is 25.93 .

  
Table 4: Grating Tilt Positions