MERCATOR

HERMES Fibre-fed echelle spectrograph

HERMES (High Efficiency and Resolution Mercator Echelle Spectrograph) is a fibre-fed prism-cross-dispersed echelle spectrograph. A full description of the instrument can be found in Raskin et al., 2011, A&A 526, A69.

The HERMES project is a collaboration between the KULeuven, the Université Libre de Bruxelles and the Belgian Royal Observatory with contributions from the Observatoire de Genève (Switzerland) and the Thüringer Landessternwarte Tautenburg (Germany).

HERMES spectrograph

Overview

The HERMES spectrograph is mounted in a temperature-controlled room and fibre-fed from the Nasmyth A focal station through an atmospheric dispersion corrector (ADC). Hermes features a fixed wavelength setting of 377-900 nm in a single exposure, with a choice of observing modes:

Detector

Hermes is equipped with an E2V 42-90 detector of 2048 by 4608 pixels. The size of the detector enables coverage of the 377-900 nm wavelength range in one fixed setting. For all orders shortwards of 838 nm the full free spectral range is recorded on the detector. Only for the 3 orders longwards of 838 nm the order extremes are truncated. See the layout of the spectral orders on the detector.

Data reduction with HermesDRS

For the default mode of Hermes (HRF mode), a dedicated automated data reduction pipeline and radial velocity toolkit (HermesDRS) is available. HermesDRS provides quick-look analysis after each exposure, and full data reduction at the end of each night. Currently, we are using version 4.0 of HermesDRS.

For data obtained using the simultaneous wavelength reference mode (LRF_OBJ_WRF_TH), the data reduction is not automatic, but it can be done using the scripts provided with version 4.0 of HermesDRS. Automated data reduction for the simultaneous wavelength reference mode is foreseen for the next release of HermesDRS.

Applying for time

Hermes has been available for regular science use from Semester 2009B onwards. Time allocations for ITP and CAT programmes are always in visitor mode, and by full nights only.

Acknowledge Hermes and Mercator in publications

See Also