HIRES (High Resolution Echelle Spectrometer) is a grating cross-dispersed, echelle spectrograph capable of operating between 0.3 and 1.0 microns. Although adjustable slits are available by special request, almost all observers choose from a number of slit plates which provide resolutions between roughly 25,000 and 85,000. These slits are available in a variety of lengths since order separation varies between 6 and 43 arcseconds. HIRES does not currently have multi-slit capability.

Observers can request one of two configurations. HIRESb and HIRESr use different cross-dispersers and collimators, which are optimized for short and long wavelength observations, respectively. The efficiency of the two is equal at approximately 4200 Angstroms. Switching between the two is not possible during the night.

Spectral coverage is complete shortward of 6200 Angstroms. Longward of this, two different echelle settings are necessary to achieve complete coverage. Aside from the possible gaps in coverage at long wavelengths, the spectral span per exposure ranges from about 3000 Angstroms for short wavelength settings, to about 4500 Angstroms at long wavelength settings.

Since HIRES is mounted at a nasymth platform, fields will rotate during an exposure. If desired though, an image rotator can be introduced into the light path which will maintain the slit orientation at a particular PA or at the parallactic angle. This rotator is always available and can be moved into or out of the beam remotely. Other devices which observers can select at will are an exposure meter for accurate control of signal levels and an iodine cell for precise radial velocity work.

More detailed information about HIRES can be found in these papers.