The FALCON concept: multi-object spectroscopy combined with MCAO in near-IR

A large fraction of the present-day stellar mass was formed between z=0.5 and z~3 and our understanding of the formation mechanisms at work at these epochs requires both high spatial and high spectral resolution: one shall simultaneously} obtain images of objects with typical sizes as small as 1-2kpc(~0''.1), while achieving 20-50 km/s (R >= 5000) spectral resolution. The obvious instrumental solution to adopt in order to tackle the science goal is therefore a combination of multi-object 3D spectrograph with multi-conjugate adaptive optics in large fields. A partial, but still competitive correction shall be prefered, over a much wider field of view. This can be done by estimating the turbulent volume from sets of natural guide stars, by optimizing the correction to several and discrete small areas of few arcsec2 selected in a large field (Nasmyth field of 25 arcmin) and by correcting up to the 6th, and eventually, up to the 60th Zernike modes. Simulations on real extragalactic fields, show that for most sources (>80%), the recovered resolution could reach 0".15-0".25 in the J and H bands. Detection of point-like objects is improved by factors from 3 to >10, when compared with an instrument without adaptive correction. The proposed instrument concept, FALCON, is equiped with deployable mini-integral field units (IFUs), achieving spectral resolutions between R=5000 and 20000. Its multiplex capability, combined with high spatial and spectral resolution characteristics, is a natural ground based complement to the next generation of space telescopes.Comment: ESO Workshop Proceedings: Scientific Drivers for ESO Future VLT/VLTI Instrumentation, 10 pages and 5 figure

Updated optical design and trade-off study for MOONS, the Multi-Object Optical and Near Infrared spectrometer for the VLT

This paper presents the latest optical design for the MOONS triple-arm spectrographs. MOONS will be a Multi-Object Optical and Near-infrared Spectrograph and will be installed on one of the European Southern Observatory (ESO) Very Large Telescopes (VLT). Included in this paper is a trade-off analysis of different types of collimators, cameras, dichroics and filters.Comment: 10 pages, 8 figures, 5 tables. Presented at SPIE Astronomical Telescope + Instrumentation 2014 (Ground-based and Airbone Instrumentation for Astronomy 5, 9147-84). To be published in Proceeding of SPIE Volume 914

GYES, a multifibre spectrograph for the CFHT

We have chosen the name of GYES, one of the mythological giants with one hundred arms, offspring of Gaia and Uranus, for our instrument study of a multifibre spectrograph for the prime focus of the Canada-France-Hawaii Telescope. Such an instrument could provide an excellent ground-based complement for the Gaia mission and a northern complement to the HERMES project on the AAT. The CFHT is well known for providing a stable prime focus environment, with a large field of view, which has hosted several imaging instruments, but has never hosted a multifibre spectrograph. Building upon the experience gained at GEPI with FLAMES-Giraffe and X-Shooter, we are investigating the feasibility of a high multiplex spectrograph (about 500 fibres) over a field of view 1 degree in diameter. We are investigating an instrument with resolution in the range 15000 to 30000, which should provide accurate chemical abundances for stars down to 16th magnitude and radial velocities, accurate to 1 km/s for fainter stars. The study is led by GEPI-Observatoire de Paris with a contribution from Oxford for the study of the positioner. The financing for the study comes from INSU CSAA and Observatoire de Paris. The conceptual study will be delivered to CFHT for review by October 1st 2010.Comment: Contributed talk at the Gaia ELSA conference 2010, S\`evres 7-11 June 2010, to be published on the EAS Series, Editors: C. Turon, F. Arenou & F. Meynadie

MOONS: a Multi-Object Optical and Near-infrared Spectrograph for the VLT

MOONS is a new conceptual design for a Multi-Object Optical and Near-infrared Spectrograph for the Very Large Telescope (VLT), selected by ESO for a Phase A study. The baseline design consists of 1000 fibers deployable over a field of view of 500 square arcmin, the largest patrol field offered by the Nasmyth focus at the VLT. The total wavelength coverage is 0.8um-1.8um and two resolution modes: medium resolution and high resolution. In the medium resolution mode (R=4,000-6,000) the entire wavelength range 0.8um-1.8um is observed simultaneously, while the high resolution mode covers simultaneously three selected spectral regions: one around the CaII triplet (at R=8,000) to measure radial velocities, and two regions at R=20,000 one in the J-band and one in the H-band, for detailed measurements of chemical abundances. The grasp of the 8.2m Very Large Telescope (VLT) combined with the large multiplex and wavelength coverage of MOONS - extending into the near-IR - will provide the observational power necessary to study galaxy formation and evolution over the entire history of the Universe, from our Milky Way, through the redshift desert and up to the epoch of re-ionization at z>8-9. At the same time, the high spectral resolution mode will allow astronomers to study chemical abundances of stars in our Galaxy, in particular in the highly obscured regions of the Bulge, and provide the necessary follow-up of the Gaia mission. Such characteristics and versatility make MOONS the long-awaited workhorse near-IR MOS for the VLT, which will perfectly complement optical spectroscopy performed by FLAMES and VIMOS.Comment: 9 pages, 5 figures. To appear in the proceedings of the SPIE Astronomical Instrumentation + Telescopes conference, Amsterdam, 201

X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope

X-shooter is the first 2nd generation instrument of the ESO Very Large Telescope(VLT). It is a very efficient, single-target, intermediate-resolution spectrograph that was installed at the Cassegrain focus of UT2 in 2009. The instrument covers, in a single exposure, the spectral range from 300 to 2500 nm. It is designed to maximize the sensitivity in this spectral range through dichroic splitting in three arms with optimized optics, coatings, dispersive elements and detectors. It operates at intermediate spectral resolution (R~4,000 - 17,000, depending on wavelength and slit width) with fixed echelle spectral format (prism cross-dispersers) in the three arms. It includes a 1.8"x4" Integral Field Unit as an alternative to the 11" long slits. A dedicated data reduction package delivers fully calibrated two-dimensional and extracted spectra over the full wavelength range. We describe the main characteristics of the instrument and present its performance as measured during commissioning, science verification and the first months of science operations.Comment: accepted for publication in A&

MOONS: the Multi-Object Optical and Near-infrared Spectrograph for the VLT

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