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Below-the-Slit Filter Wheel

Below the slit is a six-position filter wheel containing several 2--in. blocking filters. These generally remain in place, and can be accessed only when the spectrograph is off the telescope. They are positioned by turning a knob on the mounting plate [S]; the corresponding position number becomes centered in the window when the filter is seated. The present filter complement (also listed [T] on Side 3 of the spectrograph) is:

  1. Copper sulfate (transmits < 6000Å)
  2. UV36 (transmits > 3600Å)
  3. L38 (transmits > 3800Å)
  4. L42 (transmits > 4200Å)
  5. Open
  6. Y48 (transmits > 4800Å)

Do not attempt to turn the filter wheel past 6 to 1 --- it will break. Figure 7.1 displays the transmissions of the blocking filters.

Figure 7.1: Available filters.

Pat Hall - Wed Oct 4 11:02:37 MST 1995