Science Highlights from 4 Years of NIRSPEC on the Keck II Telescope

Abstract

NIRSPEC is the facility-class near-infrared spectrometer for the W.M. Keck Observatory. Commissioned from April–August 1999, NIRSPEC has been used extensively and successfully over the last four years. In high-resolution mode (R ~ 20,000–30,000), NIRSPEC science includes studies of comets and solar system bodies, abundance studies in red giants, the kinematics of the population of stars near the Galactic Center, protostars and disks, low-mass spectroscopic binaries, brown dwarfs, galactic photo-dissociation regions and the study of extragalactic super clusters. NIRSPEC is an all-reflecting f/10 spectrograph with a 120mm collimated beam. A single echelle grating with ~22 l/mm is used in quasi-Littrow mode with an out-of-plane angle of 5 degrees. The collimator is an off-axis parabola and the camera is a three-mirror anastigmat. All of the optical components in the spectrometer chain are diamond-machined, post-polished aluminum mirrors with silver-coatings for high throughput. Spectral coverage from 0.95–5.5 μm is achieved with an ALADDIN III 1024 × 1024 InSb detector having a median dark current of ~0.2 e/s/pixel and a readout noise of ~25 electrons rms using 16 reads. NIRSPEC has a cryogenic image rotator, a set of fixed reflective slits and an independent slit-viewing camera with a field of view of 46^″ × 46^″. Examples of high resolution spectra are described to illustrate performance.