Bernard Delabre

Design, construction, and performance of UVES, the echelle spectrograph for the UT2 Kueyen Telescope at the ESO Paranal Observatory

We describe the design and construction of the ESO UV-visual echelle spectrograph and the performance that was measured during its commissioning 1999. UVES is a dual-beam, grating crossdispersed echelle spectrograph. The resolution for a 1 arcsecond slit is 40,000. With narrower slits, resolutions of up to 80,000 and 115,000 are achieved with adequate sampling. UVES provides order separations of minimum 10 arcseconds at any wavelength between 320 and 1050 nm. The wavelength coverage is 100 nm in the blue arm and 200 or 400 nm in the red arm, with possibility to use a dichroic. Some concepts pioneered in UVES are now increasingly being used in other echelle spectrograph for large telescopes: a white pupil design, very steep replicated mosaic echelles, and large refractive cameras with external focus. Regular observations are starting in April 2000 at the Nasmyth focus of Kueyen, Unit Telescope 2 of the VLT array.

SINFONI: integral field spectroscopy at 50-milli-arcsecond resolution with the ESO VLT

SINFONI is an adaptive optics assisted near-infrared integral field spectrometer for the ESO VLT. The Adaptive OPtics Module (built by the ESO Adaptive Optics Group) is a 60-elements curvature-sensor based system, designed for operations with natural or sodium laser guide stars. The near-infrared integral field spectrometer SPIFFI (built by the Infrared Group of MPE) provides simultaneous spectroscopy of 32 x 32 spatial pixels, and a spectral resolving power of up to 3300. The adaptive optics module is in the phase of integration; the spectrometer is presented tested in the laboratory. We provide an overview of the project, with particular emphasis on the problems encountered in designing and building an adaptive optics assisted spectrometer.

CRIRES: A High Resolution Infrared Spectrograph for ESO’s VLT

CRIRES is a cryogenic, pre-dispersed, infrared echelle spectrograph designed to provide a resolving power lambda/(Delta lambda) of 105 between 1 and 5mu m at the Nasmyth focus B of the 8m VLT unit telescope #1 (Antu). A curvature sensing adaptive optics system feed is used to minimize slit losses and to provide diffraction limited spatial resolution along the slit. A mosaic of 4 Aladdin~III InSb-arrays packaged on custom-fabricated ceramics boards has been developed. This provides for an effective 4096x512 pixel focal plane array, to maximize the free spectral range covered in each exposure. Insertion of gas cells to measure high precision radial velocities is foreseen. For measurement of circular polarization a Fresnel rhomb in combination with a Wollaston prism for magnetic Doppler imaging is foreseen. The implementation of full spectropolarimetry is under study. This is one result of a scientific workshop held at ESO in late 2003 to refine the science-case of CRIRES. Installation at the VLT is scheduled during the first half of 2005. Here we briefly recall the major design features of CRIRES and describe its current development status including a report of laboratory testing.

MAD the ESO multi-conjugate adaptive optics demonstrator

Multi-Conjugate Adaptive Optics (MCAO) is working on the principle to perform wide field of view atmospheric turbulence correction using many Guide Stars located in and/or surrounding the observed target. The vertical distribution of the atmospheric turbulence is reconstructed by observing several guide stars and the correction is applied by some deformable mirrors optically conjugated at different altitudes above the telescope. The European Southern Observatory together with external research institutions is going to build a Multi-Conjugate Adaptive Optics Demonstrator (MAD) to perform wide field of view adaptive optics correction. The aim of MAD is to demonstrate on the sky the feasibility of the MCAO technique and to evaluate all the critical aspects in building such kind of instrument in the framework of both the 2nd generation VLT instrumentation and the 100-m telescope OWL. In this paper we present the conceptual design of the MAD module that will be installed at one of the VLT unit telescope in Paranal to perform on-sky observations. MAD is based on a two deformable mirrors correction system and on two multi-reference wavefront sensors capable to observe simultaneously some pre-selected configurations of Natural Guide Stars. MAD is expected to correct up to 2 arcmin field of view in K band.

ESPRESSO: the Echelle spectrograph for rocky exoplanets and stable spectroscopic observations

ESPRESSO, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will combine the efficiency of modern echelle spectrograph design with extreme radial-velocity precision. It will be installed on ESOs VLT in order to achieve a gain of two magnitudes with respect to its predecessor HARPS, and the instrumental radialvelocity precision will be improved to reach cm/s level. Thanks to its characteristics and the ability of combining incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in various fields of astronomy. The main scientific objectives will be the search and characterization of rocky exoplanets in the habitable zone of quiet, nearby G to M-dwarfs, and the analysis of the variability of fundamental physical constants. We will present the ambitious scientific objectives, the capabilities of ESPRESSO, and the technical solutions of this challenging project.

HARPS: a new high-resolution spectrograph for the search of extrasolar planets

HARPS is a high-resolution spectrograph dedicated to the search for extra-solar planets by means of precise radial- velocity measurements. It will be installed on the ESO 3.6-m telescope at the ESO La Silla observatory and should start its operation son end 2002. The observations will provides for many solar-type stars of the solar vicinity a high number of RV measurements with 1 ms-1 accuracy and will allow the detection of Saturn-like planets. The instrument is a fiber-fed and cross-dispersed echelle spectrograph. It has been designed and optimized to measure the Doppler shift of the stellar spectrum by means of cross correction of the spectrum with a numerical mask. For this purpose the entire spectrum in the wavelength range from 380 nm to 680 nm is imaged on a 4k4 mosaic CCD detector at a spectral resolution of about R equals 90,000. Wavelength calibration is provided by a ThAr lamp simultaneously imaged on the CCD. The HARPS spectrograph is also characterized by its high optical efficiency and the high thermo-mechanical stability. Indeed the whole instrument will be temperature controlled and operated in vacuum, in order to assure its short and long-term stability. This paper summarizes the present status of the project and describes the optical and instrument design of HARPS. Also a short presentation of the scientific objectives pursued with HARPS is given by the author.

Implementation of MACAO for SINFONI at the VLT, in NGS and LGS modes

The European Southern Observatory (ESO) and the Max Planck Institut fur extraterrestrische Physik (MPE) are jointly developing SINFONI, an Adaptive Optics (AO) assisted Near Infrared Integral Field Spectrometer, which will be installed in the first quarter of 2004 at the Cassegrain focus of YEPUN (VLT UT4). The Adaptive Optics Module, a clone of MACAO, designed and built by ESO, is based on a 60 elements curvature system. It feeds the 3D spectrograph, SPIFFI, designed and built by MPE, with higher than 50% K band Strehl for bright (V<12) on-axis Natural Guide Stars (NGS) and less than 35 mas/hour image motion. The AO-Module will be the first curvature AO system operated in Laser Guide Star (LGS) mode, using a STRAP system for the tip/tilt sensing. The Strehl performance in the LGS mode is expected to be better than 30% in K band.

Future of filled aperture telescopes: is a 100-m feasible?

We explore the scientific case and the conceptual feasibility of giant filled aperture telescopes, in the light of science goals needing an order of magnitude increase in aperture size, and investigate the requirements (and challenges) these imply for possible technical options in the case of a 100 m telescope. The 100-m f/6.4 telescope optical concept is of a four mirror design with segmented, spherical primary and secondary mirrors, and 8-m class aspheric tertiary and quaternary mirrors, providing a 3 arc minutes field of view. Building on the experience of the VLT and other large telescope projects, we investigate mirror fabrication issues, a possible mechanical solution, the requirements for the absolutely essential adaptive optics system and for the instrumentation package, and the implications for budget and schedule.

FLAMES: a multi-object fiber facility for the VLT

FLAMES is a fiber facility to be installed on the A platform of the VLT Kueyen telescope, which can feed up to three spectrographs with fibers positioned over a corrected 25 arcminutes field of view. The initial configuration will include connections to the GIRAFFE and to the red arm of the UVES spectrographs, the latter, located on the Nasmyth B platform of the same telescope, is already in operation as a long slit stand alone instrument. The 8 fibers to UVES will give R approximately 45000 and a large spectral coverage, while GIRAFFE will be fed by 132 single fibers, or by 15 deployable integral field units or by one central large integral unit. GIRAFFE will be equipped with two gratings, giving R equals 5000-9000 and R equals 15000-25000 respectively. It will be possible to obtain GIRAFFE and UVES observations simultaneously. Special attention is paid to optimizing night operations and to providing appropriate data reduction. The instrument is rather complex and it is now in the construction phase; in addition to ESO, its realization has required the collaboration of several institutes grouped in 4 consortia.

HAWK-I: A new wide-field 1- to 2.5-μm imager for the VLT

HAWK-I (High Acuity, Wide field K-band Imaging) is a 0.9 μm - 2.5 μm wide field near infrared imager designed to sample the best images delivered over a large field of 7.5 arcmin x 7.5 arcmin. HAWK-I is a cryogenic instrument to be installed on one of the Very Large Telescope Nasmyth foci. It employs a catadioptric design and the focal plane is equipped with a mosaic of four HAWAII 2 RG arrays. Two filter wheels allow to insert broad band and narrow band filters. The instrument is designed to remain compatible with an adaptive secondary system under study for the VLT.