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

TL;DR

HERMES is a high-resolution fibre-fed spectrograph designed for the Mercator telescope, offering high efficiency and spectral coverage suitable for time-series observations of variable stellar phenomena.

Contribution

This paper presents the complete design, implementation, and performance analysis of the HERMES spectrograph, highlighting its high resolution, efficiency, and suitability for astrophysical time-series studies.

Findings

Spectral resolution of 85000 achieved

Spectral coverage from 377 to 900nm in a single exposure

Peak efficiency of 28%

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 85000 (63000 for the low-resolution fibre), a spectral coverage from 377 to 900nm 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.