HIRES

HIRES
Name	HIRES
Type	Spectrograph

HIRES

HIRES is a high-resolution echelle spectrograph used for precision spectroscopy on large optical telescopes. It provides high spectral resolving power for studies of stellar atmospheres, exoplanet radial velocities, chemical abundances, and cosmological absorption systems. The instrument has been deployed in observational programs alongside instruments and facilities such as Keck Observatory, Hubble Space Telescope, European Southern Observatory, Subaru Telescope, and Very Large Telescope for coordinated campaigns and follow-up.

Overview

HIRES is an optical echelle spectrograph designed to deliver resolving powers often exceeding R~50,000, enabling fine structure measurements in spectra from targets like Proxima Centauri, Sirius, Vega, HD 209458, and faint quasars such as 3C 273. It combines a cross-dispersed echelle grating, precision optics, and detector arrays to record broad wavelength coverage across many orders. HIRES has been integral to surveys associated with projects and institutions including Keck Observatory, Carnegie Institution for Science, California Institute of Technology, NASA, and the Institute for Astronomy at the University of Hawaii. Observing programs using HIRES intersect with research on objects observed by Gaia, Spitzer Space Telescope, Chandra X-ray Observatory, James Webb Space Telescope, and ground campaigns like the Sloan Digital Sky Survey.

History

The development of HIRES involved collaborations among instrument builders and observatory teams associated with W. M. Keck Observatory, California Institute of Technology, University of California, Berkeley, and industrial partners in optical fabrication and detector manufacture represented by companies that have supplied gratings and CCDs to projects associated with MIT, Harvard–Smithsonian Center for Astrophysics, and Max Planck Institute for Astronomy. Commissioning runs placed HIRES on nights alongside other pioneering instruments such as HIRES-NIR, NIRSPEC, ESPaDOnS, and HARPS for cross-calibration. Early science with HIRES contributed to landmark detections and measurements published alongside results from teams led by scientists connected to awards like the Nobel Prize in Physics, recognitions at the AAS meetings, and contributions to catalogs used by SIMBAD and the NASA Exoplanet Archive.

Technical Specifications

HIRES employs a large echelle grating in a white-pupil or quasi-Littrow configuration, coupled to a cross-disperser prism or grating and a camera system delivering high image quality on charge-coupled devices produced by suppliers linked to projects at NASA Goddard Space Flight Center, Jet Propulsion Laboratory, and European Southern Observatory. Typical instrument parameters include: - Spectral resolving power R (λ/Δλ) up to and beyond 100,000 for narrow-slit configurations used on bright targets such as Betelgeuse and Polaris. - Wavelength coverage spanning the near-ultraviolet through red optical bands overlapping with sensitivity ranges of Hubble Space Telescope instruments and ground spectrographs like UVES and HARPS-N. - Calibration systems utilizing emission lamps historically related to manufacturers supplying standards to observatories and modern frequency references comparable to those developed with National Institute of Standards and Technology expertise and laser comb technologies pioneered by groups at Menlo Systems and Kavli Institute for Theoretical Physics. - Detectors with multi-amplifier readout and cooling systems drawn from technologies used in instruments at Gemini Observatory and Subaru Telescope.

Applications

HIRES has been used across a wide range of astrophysical programs: precision radial velocity searches for planets around stars such as 51 Pegasi, Gliese 581, and HD 189733; detailed chemical abundance analyses in stars including Arcturus, Mu Cephei, and halo stars studied in surveys associated with Keck/DEIMOS follow-ups; intergalactic medium studies via quasar absorption lines exemplified by observations of QSO 0957+561 and damped Lyman-alpha systems relevant to Planck and WMAP cosmology comparisons. Programs employing HIRES often collaborate with teams from institutions such as Harvard University, Princeton University, University of Cambridge, University of Tokyo, and Observatoire de Paris to interpret spectra in the context of stellar evolution, nucleosynthesis, and galaxy formation.

Performance and Comparison

In direct comparisons, HIRES performance is often assessed against spectrographs like HARPS, UVES, HIRES-NIR, ESPRESSO, and SOPHIE. HIRES offers competitive resolving power and broad wavelength coverage that benefits abundance and atmospheric diagnostics, while instruments such as HARPS and ESPRESSO emphasize ultra-stable radial velocity precision enabled by vacuum chambers and laser frequency combs developed in partnerships with institutions like Observatoire de Genève and Observatoire de la Côte d'Azur. HIRES’s large telescope aperture pairing at sites like Mauna Kea yields high signal-to-noise on faint targets compared to smaller-aperture facilities, supporting deep surveys coordinated with Sloan Digital Sky Survey and follow-up of Kepler and TESS targets.

Criticisms and Limitations

Limitations of HIRES cited in the community include instrumental radial velocity stability challenges compared with stabilized spectrographs such as HARPS and ESPRESSO, requiring intensive calibration campaigns and software pipelines developed with expertise from teams at University of Geneva, University of California, Santa Cruz, and Carnegie Institution for Science. Environmental sensitivity at mountain-top sites like Mauna Kea introduces thermal and pressure variations that affect long-term comparisons with instruments housed in vacuum vessels associated with projects at European Southern Observatory. Detector cosmetics and order overlap at blue wavelengths pose reduction complexities addressed by data reduction systems contributed by groups at University of Hawaii, UCO/Lick Observatory, and consortium partners from Caltech and MIT.

Category:Spectrographs