arXiv subjects

Didier Boudon

Publications and source records attributed to Didier Boudon.

3 recordsLinked to original sources

arXiv2026

4MOST Low Resolution Spectrographs Characterization in Chile

4MOST, the 4m Multi Object Spectroscopic Telescope, is the optical, fibre-fed, MOS facility for the VISTA telescope at ESO's Paranal Observatory in Chile. Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. The 4MOST consortium consists of several institutes in Europe and Australia under leadership of the Leibniz-Institut fur Astrophysik Potsdam (AIP). This paper focuses on the successful testing, installation and technical commissioning of the Low Resolution Spectrographs (LRS-A and B) for the 4MOST instrument at ESO's Paranal Observatory, Chile. This work was completed on October 18. 2025. Details on the assembly, integration, and performance of both 4MOST spectrographs from their arrival in the integration hall through to the telescope installation are provided. Attention is given to the optimization of procedures implemented to enhance performance and meet the expected top-level requirements. The 4MOST LRS features 2436 fibres split into two low-resolution spectrographs LRS-A and LRS-B (1624 fibres, three arms, 370-950 nm, R > 4000) and one high-resolution spectrograph (812 fibres, three arms, ~44-69 nm coverage each, R > 18000). The fibre positioner covers a hexagonal field of view of ~4.1 deg2. The fibers are 85 {\mu}m core with an output beam at f/3. The Centre de Recherche Astrophysique de Lyon (CRAL) had the full responsibility for the two low-resolution spectrographs. Each of them is composed of an off-axis Schmidt collimator that produces a 200 mm beam, which is split into three spectral arms by dichroics and directed to F/1.73 cameras with standard 6k x 6k 15 microns pixel CCD detectors.

astro-ph.IM↗

arXiv2026

ESO-VLT BlueMUSE instrument - Conceptual Design for Phase A

BlueMUSE is a blue-optimised, medium spectral resolution, panoramic integral field spectrograph under development for the ESO's Very Large Telescope (VLT). The project is now entering preliminary design phase. With an optimised transmission down to 350 nm, spectral resolution of R $\sim$ 3500 on average across the wavelength range, and a large FoV (1 arcmin2), BlueMUSE will open up a new range of galactic and extragalactic science cases facilitated by its specific capabilities. BlueMUSE consists of several subsystems arranged along the light path. A calibration unit reproduces the VLT's optical conditions, while the fore optics reshape the telescope's focal image. The splitting and relay optics divide the field of view into 16 channels, each feeding an integral field unit that contains an image slicer, a spectrograph, and a detector vessel. The image slicer converts the 2D sub-field into a 1D pseudo-slit, which the spectrograph disperses into spectra recorded by a 4k x 4k CCD in each detector vessel. A vacuum and cryogenic system cools the detectors, and the data reduction software processes the raw data into data cubes which are subsequently processed by a data analysis software system. All subsystems are supported by the instrument main structure and enclosed in a thermal housing for stability. The whole instrument is managed by an integrated control system combining electronics and software. This paper summarizes the baseline architecture, interfaces, and functional descriptions of the BlueMUSE instrument at the start of Design Phase. This architecture is derived from the top-level requirements and the experience acquired from MUSE. It presents the global concepts along with their preliminary performance estimates.

astro-ph.IM↗

arXiv2018

ELT HARMONI: Image Slicer Preliminary Design

Harmoni is the ELT's first light visible and near-infrared integral field spectrograph. It will provide four different spatial scales, ranging from coarse spaxels of 60 x 30 mas best suited for seeing limited observations, to 4 mas spaxels that Nyquist sample the diffraction limited point spread function of the ELT at near-infrared wavelengths. Each spaxel scale may be combined with eleven spectral settings, that provide a range of spectral resolving powers from R 3500 to R 20000 and instantaneous wavelength coverage spanning the 0.47 - 2.45 μm wavelength range of the instrument. The consortium consists of several institutes in Europe under leadership of Oxford University. Harmoni is starting its Final Design Phase after a Preliminary Design Phase in November, 2017. The CRAL has the responsibility of the Integral Field Unit design linking the Preoptics to the 4 Spectrographs. It is composed of a field splitter associated with a relay system and an image slicer that create from a rectangular Field of View a very long (540mm) output slit for each spectrograph. In this paper, the preliminary design and performances of Harmoni Image Slicer will be presented including image quality, pupil distortion and slit geometry. It has been designed by CRAL for Harmoni PDR in November, 2017. Special emphases will be put on straylight analysis and slice diffraction. The optimisation of the manufacturing and slit geometry will also be reported.

astro-ph.IM↗