HERMES: a high-resolution fibre-fed spectrograph for the Mercator telescope^⋆

G. Raskin¹, H. Van Winckel¹, H. Hensberge², A. Jorissen³, H. Lehmann⁴, C. Waelkens¹, G. Avila⁵, J.-P. De Cuyper², P. Degroote¹, R. Dubosson⁶, L. Dumortier², Y. Frémat², U. Laux⁴, B. Michaud⁶, J. Morren⁷, J. Perez Padilla¹, W. Pessemier¹, S. Prins¹, K. Smolders¹, S. Van Eck³ and J. Winkler⁴

¹ Instituut voor Sterrenkunde, K.U.Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
e-mail: Gert.Raskin@ster.kuleuven.be
² Royal Observatory of Belgium, Ringlaan 3, 1180 Brussel, Belgium
³ Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles, CP 226, Boulevard du Triomphe, 1050 Brussels, Belgium
⁴ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
⁵ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
⁶ Observatoire de Genève, Chemin des Maillettes 51, 1290 Sauverny, Switzerland
⁷ Dept. of Physics and Astronomy, K.U.Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

Received: 19 July 2010
Accepted: 11 October 2010

Abstract

The HERMES high-resolution spectrograph project aims at exploiting the specific potential of small but flexible telescopes in observational astrophysics. The optimised optical design of the spectrograph is based on the well-proven concept of white-pupil beam folding for high-resolution spectroscopy. In this contribution we present the complete project, including the spectrograph design and procurement details, the telescope adaptor and calibration unit, the detector system, as well as the optimised data-reduction pipeline. We present a detailed performance analysis to show that the spectrograph performs as specified both in optical quality and in total efficiency. With a spectral resolution of 85 000 (63 000 for the low-resolution fibre), a spectral coverage from 377 to 900 nm in a single exposure and a peak efficiency of 28%, HERMES proves to be an ideal instrument for building up time series of high-quality data of variable (stellar) phenomena.