Echelle Spectrograph Camera/CCD Choices

• Red Long Camera/Tek2048.
  590 mm focal length camera with overcoated silver optics (dead below 4000Å). Used with Tektronix 2048x2048 CCD, 80% QE at 5000Å, still 40% at 3500Å, very little fringing in red. 3 e- readout noise. This or the Blue Long Camera are the normal choices.

• Blue Long Camera/Tek2048.
  590 mm focal length camera with blue optimized optics (Al, plus an AR coat on the transmitting optics which starts to drop quickly past 5500Å). Used with Tektronix 2048x2048 CCD, 80% QE at 5000Å, still 40% at 3500Å, very little fringing in red. 3 e- readout noise. This or the Red Long Camera are the normal choices.

• Air Schmidt Camera/Loral3K.
  229 mm focal length camera with blue optimized coatings (Al and MgF). Loral 3072x1024 CCD with very good UV QE (70%), but 10% fringing in red, 7 e- readout noise badly affects use with faint objects.

• Folded Schmidt Camera/Tek1024.
  229 mm focal length camera with blue optimized coatings (Al and MgF). Tek 1024x1024 CCD, 80% QE at 5000Å but dies below 4000Å. 3 e- readout noise.

Figure 1. Quantum Efficiency curves for CCDs available at CTIO on 29 Dec 1995. The only ones available on the echelle spectrograph are L3k (Loral 3k), T2k (Tek2k) and T1k (Tek1k).

Figure 2.Old data showing ratio of red/blue long camera transmission (using the same detector on either camera). The optics of the blue long camera have since been realuminized, so the ratio at 8000A now may be lower than is shown in the figure.