HIRES: The High Resolution Echelle Spectrometer on the Keck Telescope
Session 11 -- Gemini, Keck, Seeing
Display presentation, Wednesday, January 12, 9:30-6:45, Salons I/II Room (Crystal Gateway)

## [11.01] HIRES: The High Resolution Echelle Spectrometer on the Keck Telescope

Steven S. Vogt, Michael J. Keane (UCO/Lick Observatory)

We describe the high resolution echelle spectrometer (HIRES) now in operation on the Keck Telescope. HIRES, which is permanently located at a Nasmyth focus, is a standard in-plane echelle spectrometer with grating post dispersion. The collimated beam size is $12\arcsec$, and the echelle is a $1 \times 3$ mosaic, $12\arcsec$ by $48\arcsec$ in total size, of 52.6 gr/mm, R-2.6 echelles. The cross disperser is a $2 \times 1$ mosaic, $24\arcsec$ by $16\arcsec$ in size, of 250 gr/mm gratings, blazed at 7000{\AA} in 1st order.

The camera is of a unique new design: a large ($30\arcsec$ aperture) f/1.0, all spherical, all fused silica, catadioptric system with super-achromatic performance. It spans the entire chromatic range from $0.3\mu$ to $2.0\mu$, delivering 12.6 micron (rms) images, averaged over all colors and field angles, without refocus.

The detector is a thinned, backside-illuminated, Tektronix $2048^2$ CCD with 24 micron pixels, which spans the spectral region from $0.3 \mu$ to $1.1 \mu$ with very high overall quantum efficiency. Typical limiting spectral resolution of HIRES is 67,000 with this CCD pixel size.

Typical wavelength coverage per exposure is 3200--4500{\AA} in the uv/blue, 4200--5400{\AA} in the visible, and 5500--8000{\AA} in the red/near-ir. Order separations are 8--21 arcseconds in the uv/blue, and 10--40 arcseconds in the visible/near-ir. The overall throughput'' (resolution $\times$ slit width) product achieved is 39,000 arcseconds. Peak overall efficiency for the spectrograph (not including telescope and slit losses) is 13\% at 6000{\AA} .

As examples of HIRES performance, spectra of quasar absorption lines and of beryllium in metal poor stars will be shown.