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Proceedings Paper

HERMES: a high-resolution spectrograph for the Mercator Telescope
Author(s): Gert Raskin; Hans Van Winckel; Geert Davignon
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Paper Abstract

Hermes, a high-resolution fiber-fed echelle spectrograph is currently under development for the 1.2-meter Mercator Telescope at the Roque De Los Muchachos Observatory on La Palma. The optical design is based on a large R2.6 echelle grating, operating in quasi-Littrow and white-pupil configuration, and a double-prism cross-disperser. This instrument records the complete optical spectrum from 380 to 875 nm in one single exposure on a 2k x 4k CCD. Order separation is sufficiently large to record two interleaved spectra simultaneously through two 60-mm core fibers: one spectrum of the object and one of the nearby sky or, alternatively, of a wavelength calibration lamp for high-precision radial velocity measurements. This type of observations also benefits from the high instrumental stability, owing to bench-mounting the spectrograph with a fixed configuration in a precisely temperature and humidity controlled chamber. Modest telescope size calls for high detection efficiency and great efforts in the design of both the fiber link and the spectrograph itself go in that direction. We aim at a peak-efficiency larger than 25% for the complete system. With a large fiber aperture of 2.3 arcsec, the resolving powerλ/ΔλΑ is 50000, a value that can be increased to 90000 with an adjustable slit at the fiber exit. This instrument mounted on a flexible telescope has a wide astronomical scope, going from asteroseismology to binary star research and chemical studies of stars and circumstellar material. We present the spectrograph design and we report on the project status.

Paper Details

Date Published: 30 September 2004
PDF: 9 pages
Proc. SPIE 5492, Ground-based Instrumentation for Astronomy, (30 September 2004); doi: 10.1117/12.549883
Show Author Affiliations
Gert Raskin, Mercator Telescope (Spain)
Katholieke Univ. Leuven (Belgium)
Hans Van Winckel, Katholieke Univ. Leuven (Belgium)
Geert Davignon, Mercator Telescope (Spain)
Katholieke Univ. Leuven (Belgium)


Published in SPIE Proceedings Vol. 5492:
Ground-based Instrumentation for Astronomy
Alan F. M. Moorwood; Masanori Iye, Editor(s)

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