The Kitt Peak 4-meter echelle spectrograph is a versatile instrument capable of high resolution (<= 80,000 or >= 0.07Å) over a wide range of wavelengths. Its two-dimensional format (cover figure) is ideal for array detectors. Cross dispersion gratings are available (table 6) to provide efficient spectral coverage from 3000 to 10,000 Å. The echelle spectrograph is used with CCDs to obtain spectra of stars as faint as mv ~ 15 or even fainter, depending on the resolution and signal to noise required. As NOAO has an ongoing CCD evaluation program, new chips are occasionally available which may be useful for a particular application. A list of ``standard'' CCDs is given in table 8.
Overall throughput of the spectrograph and UV camera has been measured to be ~1.3% at 3900 Å and ~4.7% at 5900 Å. These values are probably also good estimates for the throughput when the long focus cameras are in use. With the UV camera, TI CCD and 58-63° echelle, spectral coverage is complete in the UV and blue spectral regions. Coverage is complete to ~7000 Å with the 31-63° echelle and TI CCD. The long focus cameras require 2048 size CCDs to obtain complete spectral coverage out to 9000 Å, but at 4000 Å a 1024 CCD will suffice. See §2.11 for examples of calculations of spectral resolution and coverage.
The instrument is operated almost completely remotely from the console room through a computer-CAMAC system. The guider-rotator allows automatic guiding and rotation of the spectrograph to
project the slit at any angle on the sky. An ICCD (Intensified CCD) acquisition TV is used for viewing the object on the slit as well as for finding guide stars.