Design of HERMES: a high-resolution fiber-fed spectrograph for the Mercator Telescope

Gert Raskin; Hans Van Winckel; Holger Lehmann

doi:10.1117/12.670226

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30 June 2006 Design of HERMES: a high-resolution fiber-fed spectrograph for the Mercator Telescope

Gert Raskin, Hans Van Winckel, Holger Lehmann

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Proceedings Volume 6269, Ground-based and Airborne Instrumentation for Astronomy; 62692M (2006) https://doi.org/10.1117/12.670226
Event: SPIE Astronomical Telescopes + Instrumentation, 2006, Orlando, Florida , United States

Abstract

HERMES is a high-resolution fiber-fed echelle spectrograph combining high throughput with high instrumental stability. The optical design is based on a large R2.7 echelle grating, operating in quasi-Littrow and white-pupil configuration, using a double-prism cross-disperser. It records the complete spectrum from 380 to 900 nm in a single exposure on a monolithic 2kx4.5k pixels CCD. HERMES offers 1) a high-resolution and high-efficiency observation mode through a 80-μm optical fiber (2.5 arcsec sky aperture) equipped with a two-slice image slicer, resulting in a resolution of λ/Δλ = 85000 and a peak-efficiency higher than 25%; and 2) a high-stability mode through a 60-μm fiber (2.15 arcsec sky aperture, R = 55000) equipped with a double fiber scrambler for improved spectrograph illumination stability. The latter mode is intended for high-precision radial velocity measurements and it offers the possibility of recording the spectrum of a wavelength calibration lamp simultaneously and interlaced with the stellar spectrum for precise tracking of instrumental drifts. To optimize instrumental stability, the spectrograph will be housed in a temperature and pressure controlled chamber, and it will operate in one fixed optical configuration. This instrument has a wide astronomical scope, going from asteroseismology to binary star research and chemical studies of stars and circumstellar material. HERMES is currently under construction and will be mounted on the 1.2-meter Mercator Telescope at the Roque de Los Muchachos Observatory on La Palma.

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Gert Raskin, Hans Van Winckel, and Holger Lehmann "Design of HERMES: a high-resolution fiber-fed spectrograph for the Mercator Telescope", Proc. SPIE 6269, Ground-based and Airborne Instrumentation for Astronomy, 62692M (30 June 2006); https://doi.org/10.1117/12.670226

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