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The MCAO Assisted Visible Imager and Spectrograph (MAVIS), is a new instrument for ESO’s Very Large Telescope. The instrument will be installed at the Nasmyth focus of the UT4 telescope and is comprised of an imager and a spectrograph which will take advantage of the unprecedented angular resolution and sky coverage provided by LGS assisted MCAO correction at visible wavelengths. The Adaptive Optics Module (AOM) is the core engine of MAVIS, devoted to multi-conjugate wavefront sensing and correction, and designed to deliver a 30×30 arcsec2 corrected field of view to the scientific instruments. In this paper we focus on the optical design of the AOM, which has been optimized to perform several tasks including field de-rotation, atmospheric dispersion correction, and adaptive optics closed-loop operations. To maximize sky coverage, the system is designed to deliver a 2 arcmin field of view for the selection of up to 3 NGS for measurement of tip-tilt. The AOM module also includes a multiple LGS WFS for high-order wavefront measurements and two post-focal DMs for wide field turbulence compensation. The proposed design is the result of a trade-off study in which particular care has been devoted to satisfy performance and operational requirements, as well as modularity. We present here a complete description of the selected optical configuration with a summary of the performance analyses.

We recommend a conceptual design study for a spectroscopic facility in the southern hemisphere comprising a large diameter telescope, fiber system, and spectrographs collectively optimized for massively-multiplexed spectroscopy. As a baseline, we propose an 11.4-meter aperture, optical spectroscopic survey telescope with a five square degree field of view. Using current technologies, the facility could be equipped with 15,000 robotically-controlled fibers feeding spectrographs over 360, Comment: Submitted to the Astro2020 Decadal Survey as a facilities white paper

This new type of very fast (F/0.95) camera is fully achromatic and made of only 3 components: a mirror and 2 fused silica lenses. The 2 lenses are glued together. The camera offers better image quality than classical Schmidt or equivalent and is much smaller and lighter. This camera was developed for the MOONS spectrograph.

The 4-meter Multi-Object Spectroscopic Telescope (4MOST) is a wide-field, high-multiplex spectroscopic survey facility under development for the Visible and Infrared Survey Telescope for Astronomy (VISTA) of the European Southern Observatory (ESO). The primary and secondary mirrors (M1 and M2) together with the Wide Field Corrector (WFC) system provide a pupil-centric and aberration corrected focal surface. The WFC is also an integral part of the metrology system. At the focal surface, we meet two wave front sensing (WFS) systems, a deployable camera at commissioning, an acquisition and guiding (A and G) unit and a secondary guiding unit. This paper provides an overview of design details and Manufacture, Assembly, Integration and Verification (MAIV) processes for the 4MOST WFC system.

ASSIST - The Adaptive Secondary Setup and Instrument STimulator is a test setup to verify the operation of three elements of the VLT Adaptive Optics Facility, namely the Deformable Secondary Mirror (DSM) and the two AO systems using this DSM, the AO system for the visible light integral field spectrograph MUSE (GALACSI) and the AO system for the IR wide field imager HAWK-I (GRAAL). To support the testing of these elements, ASSIST will provide both an interferometry setup for testing the DSM as well as a full atmospheric turbulence simulator and star simulator to mimic the conditions at the telescope. To test the instruments using the DSM, the output beam is matched the output beam of the VLT telescope, including the correct exit-pupil and high-quality imaging and a similar hardware interface is provided. Since one of the modes to be verified is nearly diffraction limited, also the thermal and vibrational stability are very important, with strong constraints on both the mechanical as well as the optical design. ASSIST is finalizing its preliminary design phase and in this paper we present the current optical and mechanical design of ASSIST and the projected performance of the test bench for both the testing and calibration of the DSM as well as for the two AO systems under test.

ASSIST: The Adaptive Secondary Setup and Instrument STimulator is the test setup for the verification and calibration of three elements of the VLT Adaptive Optics Facility.; the Deformable Secondary Mirror (DSM) the AO system for MUSE and HAWK-I (GALACSI and GRAAL). In the DSM testing mode the DSM will be tested using both interferometry and fast wave front sensing. In full AO mode, ASSIST will allow testing of the AO systems under realistic atmospheric conditions and optically equivalent to the conditions on the telescope. ASSIST is nearing its final design review and in this paper we present the current optical and mechanical design of ASSIST. In this paper we highlight some of the specific aspects of ASSIST that we are developing for ASSIST.

ESPRESSO is a high resolution UV-vis spectrograph that will be placed in the combined Coude laboratory of the ESO VLT. The instrument is in its assembly phase and the Coude optics will start to be mounted at the telescope in the first quarter of 2016. This paper describes the optics of the train and the strategies for its alignment taking into account the main constraints: accessibility, mechanical, as per built optics, tolerances and tools.

Various projects to find planets or entire planetary systems around main sequence stars in the solar neighborhood are presently under way. When ELTs will be operational, there will be literally thousands of confirmed planetary systems including spectro-photometric detections. At this point it becomes inevitable to consider the next logical step : the spectroscopic analysis of the atmospheres of these planets. High-resolution spectroscopy, i.e. resolving $v \times \sin (i)$ of these planets, in the wavelength regime of 950-5500nm is a powerful and promising tool. In view of the obvious contrast problems in detecting such planets non-LTE features are specifically targeted. Sensitivity estimates for the detection of the non-thermal OH glow in oxygen-bearing atmospheres are given. With 8m -class telescopes such a search is impossible, but a dedicated spectrograph, e.g. at the projected ESO 100m OWL telescope could detect Earth-like planets at a distance of ${\approx} 10$ parsec. A conceptual design for a dedicated spectrograph, NOCTUA, is presented. In case of ELTs of smaller size the science case changes and the instrument requirements have to be adjusted. Preparatory work with CRIRES, ESO's C ryogenic I nfra r ed E chelle S pectrograph on the VLT at $\frac{\lambda}{\Delta \lambda} \approx 10^5$ as well as other science cases are shortly discussed.

The Enhanced Resolution Imager and Spectrograph (ERIS) is the new Adaptive Optics based instrument for ESO’s VLT aiming at replacing NACO and SINFONI to form a single compact facility with AO fed imaging and integral field unit spectroscopic scientific channels. ERIS completes the instrument suite at the VLT adaptive telescope. In particular it is equipped with a versatile AO system that delivers up to 95% Strehl correction in K band for science observations up to 5 micron It comprises high order NGS and LGS correction enabling the observation from exoplanets to distant galaxies with a large sky coverage thanks to the coupling of the LGS WFS with the high sensitivity of its visible WFS and the capability to observe in dust embedded environment thanks to its IR low order WFS. ERIS will be installed at the Cassegrain focus of the VLT unit hosting the Adaptive Optics Facility (AOF). The wavefront correction is provided by the AOF deformable secondary mirror while the Laser Guide Star is provided by one of the four launch units of the 4 Laser Guide Star Facility for the AOF. The overall layout of the ERIS AO system is extremely compact and highly optimized: the SPIFFI spectrograph is fed directly by the Cassegrain focus and both the NIX’s (IR imager) and SPIFFI’s entrance windows work as visible/infrared dichroics. In this paper we describe the concept of the ERIS AO system in detail, starting from the requirements and going through the estimated performance, the opto-mechanical design and the Real-Time Computer design.

ESPRESSO is the next European exoplanets hunter. It will combine the efficiency of modern echelle spectrograph with extreme radial-velocity precision. It will be installed at Paranal's VLT in order to achieve two magnitudes gain with respect to its predecessor HARPS, and the instrumental radial-velocity precision will be improved to reach 10 cm/s level. We have constituted a Consortium of astronomical research institutes to fund, design and build ESPRESSO on behalf of and in collaboration with ESO, the European Southern Observatory. The project has passed the final design review in May 2013. The spectrograph will be installed at the Combined Coude Laboratory of the VLT, it will be linked to the four 8.2 meters Unit Telescopes through four optical "Coude trains" and will be operated either with a single telescope or with up to four UTs, enabling an additional 1.5 magnitude gain. Thanks to its characteristics and ability of combining incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in many fields of astronomy. Our main scientific objectives are, however, the search and characterization of rocky exoplanets in the habitable zone of quiet, near-by G to M-dwarfs, and the analysis of the variability of fundamental physical constants. In this paper, we will present the scientific objectives, the capabilities of ESPRESSO, the technical solutions for the system and its subsystems, enlightening the main differences between ESPRESSO and its predecessors. The project aspects of this facility are also described, from the consortium and partnership structure to the planning phases and milestones.

ESPRESSO, the VLT rocky exoplanets hunter, will combine the efficiency of modern echelle spectrograph with extreme radial-velocity precision. It will be installed at Paranal on ESO's VLT in order to achieve a gain of two magnitudes with respect to its predecessor HARPS, and the instrumental radial-velocity precision will be improved to reach 10 cm/s level. We have constituted a Consortium of astronomical research institutes to fund, design and build ESPRESSO on behalf of and in collaboration with ESO, the European Southern Observatory. The project has passed the preliminary design review in November 2011. The spectrograph will be installed at the so-called "Combined Coude Laboratory" of the VLT, it will be linked to the four 8.2 meters Unit Telescopes (UT) through four optical "Coude trains" and will be operated either with a single telescope or with up to four UTs. In exchange of the major financial and human effort the building Consortium will be awarded with guaranteed observing time (GTO), which will be invested in a common scientific program. Thanks to its characteristics and the ability of combining incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in many fields of astronomy. Our main scientific objectives are, however, the search and characterization of rocky exoplanets in the habitable zone of quiet, near-by G to M-dwarfs, and the analysis of the variability of fundamental physical constants. In this paper, we present the ambitious scientific objectives, the capabilities of ESPRESSO, the technical solutions for the system and its subsystems, enlightening the main differences between ESPRESSO and its predecessors. The project aspects of this facility are also described, from the consortium and partnership structure to the planning phases and milestones.

At least during the last ten years, the Brazilian astronomical community has been asking for an echelle spectrograph for the 1.6 m telescope installed at Pico dos Dias Observatory (Brazopolis, MG, Brazil, OPD/MCTI/LNA). Among the scientific cases are topics related to the chemical evolution of the Galaxy, asteroseismology, chemical composition and chromospheric activities of solar type stars and the relations between solar analogues and terrestrial planets. During 2009 the project finally got started. The called ECHARPE spectrograph (Espectrografo ECHelle de Alta Resolucao para o telescopio Perkin-Elmer) is being projected to offer a spectral resolution of R ~ 50000, in the range 390-900 nm and with a single exposition. It will be a bench spectrograph with two channels: blue and red, fed by two optical fibers (object, sky or calibration) with aperture of 1.5 or 2.0 arcseconds. The instrument will be placed in one of the telescope pillar ramification, in the originals installations of a Coude spectrograph and in a specially created environment controlled room. In this work we will present the scientific motivations, the conceptual optical design, the expected performance of the spectrograph, and the status of its development. ECHARPE is expected to be delivered to the astronomical community in 2014, fully prepared and optimized for remote operations.

The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telescopes to a laser driven adaptive telescope with a deformable mirror in its optical train. The project has completed the procurement phase and several large structures have been delivered to Garching (Germany) and are being integrated (the AO modules GRAAL and GALACSI and the ASSIST test bench). The 4LGSF Laser (TOPTICA) has undergone final design review and a pre-production unit has been built and successfully tested. The Deformable Secondary Mirror is fully integrated and system tests have started with the first science grade thin shell mirror delivered by SAGEM. The integrated modules will be tested in stand-alone mode in 2012 and upon delivery of the DSM in late 2012, the system test phase will start. A commissioning strategy has been developed and will be updated before delivery to Paranal. A substantial effort has been spent in 2011-2012 to prepare the unit telescope to receive the AOF by preparing the mechanical interfaces and upgrading the cooling and electrical network. This preparation will also simplify the final installation of the facility on the telescope. A lot of attention is given to the system calibration, how to record and correct any misalignment and control the whole facility. A plan is being developed to efficiently operate the AOF after commissioning. This includes monitoring a relevant set of atmospheric parameters for scheduling and a Laser Traffic control system to assist the operator during the night and help/support the observing block preparation. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

We present the science, design and performances of DIORAMAS, an imager and multi-slit spectrograph for the European Extremely Large Telescope. It covers a wide 6.8x6.8 arcmin² field, a large wavelength range 0.37 to 1.6 microns. The exceptional performances of this concept will enable extremely deep images to magnitudes AB~30 and high multiplex spectroscopy with up to ~500 slits observed simultaneously at spectral resolutions from R~300 to more than 120 slits at R~3000. The technical design is robust with only proven technology, and DIORAMAS could be developed on a timescale compatible with the EELT first light. Keywords : extremely large telescopes, spectroscopy, multi-slit spectroscopy, wide field imager, deep surveys 1. INTRODUCTION The study of first light in the Universe, the seeds of galaxies, as well as the main phases of galaxy evolution are some of the main science goals of the EELT, as identified in the Design Reference Mission (http://www.eso.org/sci/facilities/eelt/science/drm/). The sheer collecting power of the EELT will enable to observe very faint objects, with a gain in performance far superior to the gain when the 8-10m class telescopes surpassed the 4m class. On a point source, with a similar seeing, one can expect a 1.8 magnitude gain with the EELT compared to the VLT, or a factor about 27 in exposure time, a considerable advantage. However, a gain in performance is not only related to the telescope gathering power, but also, for many science investigations, to the capability of assembling large statistically representative samples of stars, galaxies, AGN, or any other (rare) categories of objects in the Universe. If one is able to observe more than one object at once, the performance gain is proportional to the number of objects observed simultaneously, and a key instrument driver is the size of the field of view adapted to the science. Large wide field imagers have been very powerful even on smaller telescopes (e.g. CFHT, VISTA, PanStarrs, soon VST, leading to LSST), where the etendue A : combining the aperture of the telescope

MUSE (Multi Unit Spectroscopic Explorer) is a second generation VLT panoramic integral field spectrograph developed for the European Southern Observatory (ESO), operating in the visible wavelength range (0.465-0.93 μm). It is composed of 24 identical Integral Field Units (IFU); each one incorporates an advanced image slicer associated with a classical spectrograph and a detector vessel. The Image Slicer subsystem -ISS- is composed of two mirror arrays of 48 spherical elements each. It is made of Zerodur and uses an innovative polishing approach where all individual components are polished together by classical method. The MUSE Spectrograph -SPS-, with fast output focal ratio of f/1.95, implements a Volume Phase Holographic Grating - VPHG. The last subsystem, the Detector Vessel -DV- includes a chip of 4k by 4k 15μm pixels supported by a Vacuum and Cryogenic System - VCS - provided by ESO. The first out of 24 IFUs for MUSE instrument has been manufactured, aligned and tested last months. First, this paper describes the optical design, the manufacturing and test results (image quality, pupil and field of view positioning) of each subsystem independently. Second, we will focus on overall system performance (image quality and positioning) of the spectrograph associated with the detector vessel. At the end, the test results (image quality, positioning, throughput, mechanical interfaces) of the first IFU for MUSE instrument will be reported. Most of them are compliant with requirements that it demonstrates that the manufacturing, integration, alignment and tests processes are mature and gives good confidence for serial production by 24 times applied to MUSE instrument.

The Multi-conjugate Adaptive Optics RelaY (MAORY) for the European Extremely Large Telescope (E-ELT) provides a corrected field of view of up to 2 arcmin diameter over the wavelength range 0.8-2.4 μm. It is expected to achieve a correction of high quality and uniformity with high sky coverage: with a seeing of 0.8 arcsec in the visible, the expected Strehl Ratio averaged over a 1 arcmin field is approximately 50% at 2.16 μm wavelength over 50% of the sky at the Galactic Pole. Wavefront correction is obtained by means of the E-ELT adaptive mirrors M4/M5 and of two post-focal deformable mirrors conjugated at 4km and 12.7km from the telescope pupil. Wavefront sensing is performed by 6 Sodium laser guide stars and by 3 natural guide stars, used to measure atmospheric and windshake tilt and to provide a reference for the focus and for the low-order aberrations induced by the Sodium layer. MAORY is located on the E-ELT Nasmyth platform and has a gravity invariant port, feeding the high angular resolution camera MICADO, and a lateral port for a detached instrument as the infrared spectrograph SIMPLE.

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 ESO's 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.

The testing and verification of ESO Very Large Telescope Adaptive Optics Facility (VLT-AOF) requires new and innovative techniques to deal with the absence of an intermediate focus on the telescope. ASSIST, The Adaptive Secondary Setup and Instrument STimulator, was developed to provide a testing facility for the ESO AOF and will allow off-telescope testing of three elements of the VLT Adaptive Optics Facility; the Deformable Secondary Mirror (DSM) and the AO systems for MUSE and HAWK-I (GALACSI and GRAAL). ASSIST will provide a full testing environment which includes an interferometric testing mode for the DSM, an on-axis testing mode with a single wavefront sensor and full operation testing modes for both the AO systems. Both natural as well as laser guide stars will be simulated under various asterisms and a realistic turbulent atmosphere will be provided for varying atmospheric conditions. ASSIST passed its final design review and is now being manufactured, integrated and tested and will be operational in mid 2011, in time for first testing with the DSM.

MAORY, the Multi-conjugated Adaptive Optics RelaY for the European Extremely Large Telescope, will be located on one of the Nasmyth platforms of the telescope to provide multi conjugated adaptive optics correction of the wavefront. The scientific instruments fed by the module will benefit from a corrected field of view of 2 arcmin diameter with high performance uniformity across the field. The two post-focal deformable mirrors are projected at high altitude by the optical system based on 5 mirrors and one dichroic which splits the laser light of the artificial reference stars from the science channel. The third deformable mirror, conjugated to the ground, is integrated into the telescope. Six laser guide stars are foreseen in order to measure the wavefront distortions and three natural guide stars are used to solve the tip-tilt indetermination problem. The natural guide stars wavefront sensors are located close to the output focal plane in order to minimize the non common path aberrations. Two output ports are foreseen: one gravity invariant located below the optical bench and one on one side of the bench to feed large instruments placed on the Nasmyth platform.

International audience; MAORY is the Multi-conjugate Adaptive Optics RelaY module for the European Extremely Large Telescope. It will be located on the Nasmyth platform of the telescope to feed scientific instruments. The module is supposed to re-image one to one the telescope focal plane with diffraction limited optical quality and to provide multi-conjugate adaptive optics correction of the wavefront distortion induced by the atmosphere. The system is based on six laser guide stars for sensing the wavefront distortion and three deformable mirrors for correcting it. A dichroic is used to split the laser light from the light of the scientific and natural guide stars channel. Two output ports, selected by the dichroic orientation, are foreseen: one in a gravity invariant configuration and one in a vertical position to feed large instruments. In this article the current optical and mechanical design are presented together with the thermal analysis.

MAORY, the multi-conjugate adaptive optics module for the E-ELT, is supposed to be placed in one of the two Nasmyth platforms of the telescope, re-imaging the focal plane with a diffraction limited image quality. The requested operating wavelength is from 0.6 to 2.4μm with a high throughput. The module will include a natural guide stars wave front sensor (NGS WFS) and a laser guide stars WFS (LGS WFS) and will feed at least two scientific instruments with a corrected field of view up to 2 arcmin, providing a mechanical de-rotation for the light instruments attached (< 4tons). We present below a preliminary optical design of the post focal relay taking count of the required performance. A particular attention is paid to the critical aspects such as the pupil de-rotation, the light splitting between the WFSs and the scientific channel and the deformable mirrors (DMs) optical parameters and dimensioning.

CRIRES is a cryogenic, pre-dispersed, infrared Echelle spectrograph designed to provide a nominal resolving power ν/Δν of 105 between 1000 and 5000 nm for a nominal slit width of 0.2". The CRIRES installation at the Nasmyth focus A of the 8-m VLT UT1 (Antu) marks the completion of the original instrumentation plan for the VLT. A curvature sensing adaptive optics system feed is used to minimize slit losses and to provide 0.2" spatial resolution along the slit. A mosaic of four Aladdin InSb-arrays packaged on custom-fabricated ceramic boards has been developed. It provides for an effective 4096 × 512 pixel focal plane array to maximize the free spectral range covered in each exposure. Insertion of gas cells is possible in order to measure radial velocities with high precision. Measurement of circular and linear polarization in Zeeman sensitive lines for magnetic Doppler imaging is foreseen but not yet fully implemented. A cryogenic Wollaston prism on a kinematic mount is already incorporated. The retarder devices will be located close to the Unit Telescope focal plane. Here we briefly recall the major design features of CRIRES and describe the commissioning of the instrument including a report of extensive testing and a preview of astronomical results.

A comprehensive suite of Adaptive Optics systems and AO-assisted instruments is currently under development for the VLT and will be built around a hyperbolic convex adaptive Deformable Secondary Mirror (DSM). In telescopes with such a secondary mirror, test and calibration of both the DSM and the science instruments using it are notoriously expensive and time-consuming. The Adaptive Secondary Setup and Instrument Stimulator (ASSIST) is being developed to allow test and integration of three key elements of the future VLT Adaptive Telescope Facility: the DSM and 2 instrument-specific adaptive optics systems (GALACSI for MUSE and GRAAL for HAWK-I). The core of ASSIST is a standalone interferometric test setup for the DSM allowing its test at its center of curvature (significantly reducing the size of the classical hyperbole focii test configuration). This setup is completed by a star simulator for both natural and laser guide stars, a turbulence generator (for realistic AO performance measurements), a corrector system generating a VLT-like exit pupil and a Nasmyth rotator simulator interfacing with the two AO systems. In this paper we present the optical architecture of ASSIST, detailing the current design of the different parts of the system, and discuss its projected performance and compliance with the test and calibration requirements.

In telescopes with a Deformable Secondary Mirror, the testing and calibration of both the DSM itself as well as the instruments using this DSM are expensive and time consuming processes. Especially in telescopes without an intermediate focus before the DSM, a number of calibrations can only be performed on a real star during night time. A full suite of Adaptive Optics systems and AO-assisted instruments is currently under development for the VLT, also know as the VLT Adaptive Telescope. ASSIST was developed to assist in the integration and testing of three elements of the VLT Adaptive Telescope Facility; the DSM; the MUSE AO system 'GALACSI' and the HAWK-I AO system 'GRAAL.' The core of ASSIST is a support infrastructure to integrate the DSM in a compact and stable test setup. A Nasmyth rotator simulator will be provided for attaching the two AO systems, while ASSIST will be fed by a star simulator and turbulence generator for realistic performance measurements of both the DSM as well as the AO system under test. An on-axis high-speed interferometer will be used for additional testing of the functional operation of the DSM. In this paper we present the requirements and design of ASSIST and the projected performance of the test bench for both the testing and calibration of the DSM as well as for the two AO systems under test.

The Multi-Conjugate Adaptive Optics Demonstrator (MAD) built by ESO with the contribution of two external consortia is a powerful test bench for proving the feasibility of Ground Layer (GLAO) and Multi-Conjugate Adaptive Optics (MCAO) techniques both in the laboratory and on the sky. The MAD module will be installed at one of the VLT unit telescope in Paranal observatory to perform on-sky observations. MAD is based on a two deformable mirrors correction system and on two multi-reference wavefront sensors (Star Oriented and Layer Oriented) 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. MAD is completing the test phase in the Star Oriented mode based on Shack-Hartmann wavefront sensing. The GLAO and MCAO loops have been successfully closed on simulated atmosphere after a long phase of careful system characterization and calibration. In this paper we present the results obtained in laboratory for GLAO and MCAO corrections testing with bright guide star flux in Star Oriented mode paying also attention to the aspects involving the calibration of such a system. A short overview of the MAD system is also given.

We present the scientific case for an Adaptive Optics Visual Echelle Spectrograph and Imager Coronograph (AVES-IMCO) that we propose as a visitor instrument for the secondary port of N AOS at the VLT. We show that such an instrument would be ideal for intermediate resolution (R=16,000) spectroscopy of faint sky-limited objects down to a magnitude of V=24.0 and will complement very effectively the near-IR imaging capabilities of CONICA. We present examples of science programmes that could be carried out with such an instrument and which cannot be addressed with existing VLT instruments. We also report on the result of a two-year design study of the instrument, with specific reference to its use as parallel instrument of NAOS.

We present the design of the SOAR Telescope Echelle Spectrograph (STELES). The instrument is part of the Brazilian participation on the 4.1m SOAR telescope second-generation instrumentation. A multi-institutional team is designing the echelle spectrograph with UV capability. In view of its high image quality and moderately large collecting area, SOAR will be able to yield high quality spectroscopic data for a large variety of objects of astrophysical interests. Another point that should be explored in SOAR is the near UV capability, not available in most of the current available high-resolution spectrographs. The proposed spectrograph is a R4 cross-dispersed echelle fed by the SOAR Nasmyth focus, operating in a quasi-Littrow white pupil configuration, and a resolving power of R ~ 50,000, covering the 300-890nm spectral range in one shot. The concept developed for this spectrograph is based on VPH grating crossdispersers and all spherical optics (including the collimator mirrors). The transfer collimator is mounted in a position so that the 100mm F/8.5 beam is resized to 50mm, allowing very compact cameras design. These modifications on the standard quasi-Littrow, white pupil configuration design yield a very efficient, compact and cheaper spectrograph.

HARPS is a new high resolution “bre-fed spectrograph dedicated to the extremely precise measurement ofstellar radial velocities. After being used for about one year including the commissioning runs we report avery successful implementation of the measures taken to maximise stability, eciency and spectral performance.Using the Simultaneous ThAr Reference Method a short term precision of 0.2 ms Š 1 during one night and a longterm precision of the order of 1 ms Š 1 have been achieved. Equipped with a fully automated data reductionpipeline that produces solar system barycentric radial velocities in near real-time, HARPS promises to deliverdata of unequalled quality. HARPS will primarily be used for the search for exoplanets and in the “eld ofasteroseismology. First exciting scienti“c results con“rm these expectations.Keywords: spectroscopy, exoplanet, asteroseismology, radial velocity 1. INTRODUCTION HARPS, the High Accuracy Radial velocity Planet Searcher saw its First Light at the 3.6m telescope of ESOsLa Silla Observatory in February 2003, exactly 3 years after the project was formally launched as a cooperativeeort between the HARPS Consortium and the European Southern Observatory ESO. The former consists ofPhysikalisches Institut der Universit¨ at Bern, Observatoire de Haute Provence (OHP) and Service dA´ eronomiedu CNRS under the leadership of Observatoire de de Gen` eve, on ESOs side substantial contributions camefrom La Silla Observatory and the Instrumentation Division at the Garching Headquarters. More details of thehistory can be found in Mayor.

FLAMES is the VLT Fibre Facility, installed and being commissioned at the Nasmyth A of UT2 (Kueyen Telescope). FLAMES has been built and assembled at the VLT telescope in about 4 years through an international collaboration between 10 institutes in 6 countries and 3 continents. It had first light with the fibre link to the red arm of UVES on April 1, and with the GIRAFFE spectrograph on July 3. We have not yet enough data to compare the observed vs. expected astronomical performances, although these first data are encouraging in many respects. We aim at proceeding soon with the remaining tests

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.

We present a preliminary design study for an adaptive optics visual echelle spectrograph and imager/coronograph for use as parallel instrument of the Nasmyth Adaptive Optics System (NAOS) on unit UT3 of the VLT. The spectrograph is intended for intermediate resolution spectroscopy of faint sources. It could be used for observations of late-type dwarfs in distant Galactic clusters and in galaxies of the local group as well as for spectroscopy of extra galactic objects like quasars and Lyman break galaxies down to a limiting magnitude of V equals 22.5. The implementation of an imaging gand coronograph mode increases the versatility of the instrument and its scientific objectives. The instrument takes advantage of Adaptive Optics at visible wavelengths both for imaging and spectroscopy. With NAOS at the VLT, the light concentration in these bands will be above approximately 60 percent of the flux in a 0.3 arcsec aperture for typical Paranal conditions. Simulations show that a gain of more than one magnitude with respect to compatible non-adaptive optical spectrography will be possible for sky- and/or detector limited observations. In addition, the smaller diffraction limit in the optical than in the IR will allow a significant gain in imaging and coronography as well. Finally, the instrument will allow gathering unprecedented experience on the performances of AO at visible wavelengths, which will be fundamental for further development of AO systems, in particular for very large telescopes.

HARPS (High-Accuracy Radial-velocity Planetary Search) is a high-resolution spectrograph dedicated to the search for extra-solar planets by means of precise radial-velocity (RV) measurements. It will be installed on the ESO 3.6-m telescope at the ESO La Silla observatory and should start its operations on end 2002. The observations will provide 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 correlation 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=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.

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.

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.

We explore solutions for the optical design of the OWL 100-m telescope, and discuss their properties, advantages and drawbacks in relation to top level requirements. Combining cost, design, fabrication and functionality issues, and taking into account the scale of the telescope, we conclude that the requirements are best met with a design based on spherical primary and secondary mirrors. The combined active and adaptive correction capability envisioned for the telescope allows substantial relaxation of otherwise critical subsystems specifications. We elaborate on the telescope correction capabilities, including alignment and focusing, and derive the structure of the optical error budget.

The European Southern Observatory is developing a medium order curvature adaptive optics system designed to be operable with minimal modification at any focus of the Very Large telescope (VLT). The first application of this AO system (MACAO) is to equip all four VLT Unit Telescope (UT) Coude foci with 60 element AO systems capable of delivering to the VLT Interferometer (VLTI) > 50% K band Strehl. The AO system being used by an interferometer is constrained to introduce minimal piston and operating as a sub-system of a large and complex instrument to have a robust architecture and simple operation. Installation of the first AO system is scheduled to begin first Quarter 2002 with completion of all four UTs by early 2004. Other applications of the MACAO system will be for use by the CRIRES and SPIFFI spectrographs.

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.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We present the preliminary study of a low cost, high performance spectrograph for the VLT, for observations in the V, R and I bands. This spectrograph is meant for intermediate (R equals 16,000) resolution spectroscopy of faint (sky and/or detector limited) sources, with particular emphasis on the study of solar-type (F-G) stars belonging to the nearest galaxies and to distant (or highly reddened) galactic clusters. The spectrograph is designed to use the adaptive optics (AO) systems at the VLT Telescope. Even if these AO systems will not provide diffraction limited images in the V, R and I bands, the photon concentration will still be above approximately 60% of the flux in an 0.3 arcsecond aperture for typical Paranal conditions. This makes the construction of a compact, cheap and efficient echelle spectrograph possible. AVES will outperform comparable non adaptive optic instruments by more than one magnitude for sky- and/or detector-limited observations, and it will be very suitable for observations in crowded fields.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An overview of the scientific goals and specifications of the instruments to be installed on the two Nasmyth foci of the Unit Telescope 2 of the VLT is presented. The combination of a fiber position with three independent spectrographs provides a powerful utility for multi-object spectroscopy of large samples. Two spectrographs will cover the optical and infrared regime at medium resolution and a fiber link to the echelle spectrograph mounted on the second Nasmyth focus will permit multiplexing observations at high spectral resolution.

We present the current design of the VIsible Multi-Object Spectrograph (VIMOS) and the Near InfraRed Multi-Object Spectrograph (NIRMOS) for the European Southern Observatory Very Large Telescope. The basic scientific requirement is to conduct very deep redshift surveys of large quantities of objects, in a minimum number of nights. The technical specifications are to allow for a large multiplex gain over a wide field, and a high efficiency of the optical train, over the 0.37 to 1.8 micrometer domain. The baseline technical concept is built around 4 channels, covering 4 X 7 X 8 arcmin2 for VIMOS and 4 X 7 X 7 arcmin2 for NIRMOS. Each channel is an imaging spectrograph with a large field adaptation lens, a collimator, grisms or filters, and a F/1.8 camera, coupled to a 2048 X 4096 pixels CCD for VIMOS, and a 20482 HgCdTe Rockwell array for NIRMOS. The unique multiplex gain allows to obtain spectra of up to 840 object simultaneously with VIMOS, and up to 170 with NIRMOS (10 arcsec slits). An integral field spectroscopy mode with more than 6400 fibers coupled to micro-lenses will be available for VIMOS, covering a 1 X 1 arcmin2 field. The VLT-VIRMOS survey of more than 150,000 galaxies is planned down to magnitudes IAB equals 24, coupled to an ultra deep probe to IAB equals 26.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

SINFONI, the SINgle Faint Object Near-infrared Investigation, is an instrument for the Very Large Telescope (VLT), designed to provide spectroscopy at the telescope diffraction limit in the near-infrared. This unique capability is achieved by combining two state-of-the-art developments, an integral field spectrometer (SPIFFI) and a curvature sensor based adaptive optics system (MACAO). SINFONI is a collaborative effort by the Max-Planck-Institut fur extraterrestrische Physik (MPE) and the European Southern Observatory (ESO).SINFONI will operate at the Cassegrain focus of Unit Telescope 1 (UT1) of the VLT, in conjunction with a Laser Guide Star (LGS) for almost complete sky coverage. It will provide integral field data cubes, with a hexagonal field of view ranging from similar to 1 " to 8 ", with corresponding pixel sizes of 0." 03 to 0." 25. The field of view contains 1024 spatial pixels, with similar to 100% filling factor in the focal plane. Spectra are obtained for each of the 1024 pixels. Spectral resolutions of R=2000 to R=4500 will be available, covering the J, H and K spectral windows. The high spectral resolution made will allow software OH suppression in the J and H bands. The detector is a 1024(2) HgCdTe HAWAII array from Rockwell. Spectroscopy of faint objects (m(K) < 21 and m(H) < 22) will be easily feasible.

ESPRESSO is the next generation ground based European exoplanets hunter. It will combine the efficiency of modern echelle spectrograph with extreme radial-velocity and spectroscopic precision. It will be installed at Paranal's VLT in order to achieve two magnitudes gain with respect to its predecessor HARPS, and the instrumental radial-velocity precision will be improved to reach 10 cm/s level. We have constituted a Consortium of astronomical research institutes to fund, design and build ESPRESSO on behalf of and in collaboration with ESO, the European Southern Observatory. The spectrograph will be installed at the Combined Coude Laboratory (CCL) of the VLT, it will be linked to the four 8.2 meters Unit Telescopes through four optical "Coude trains" and will be operated either with a single telescope or with up to four UTs, enabling an additional 1.5 magnitude gain. Thanks to its characteristics and ability of combining incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in many fields of astronomy. Our main scientific objectives are, however, the search and characterization of rocky exoplanets in the habitable zone of quiet, near-by G to M-dwarfs, and the analysis of the variability of fundamental physical constants. The project is, for most of its workpackages, in the procurement or development phases, and the CCL infrastructure is presently under adaptation work. In this paper, we present the scientific objectives, the capabilities of ESPRESSO, the technical solutions for the system and its subsystems. The project aspects of this facility are also described, from the consortium and partnership structure to the planning phases and milestones.

A cryogenic echelle spectrometer is planned for the ESO Very Large Telescope to perform high-resolution (R >= 100,000) observations in the 1 - 5 micrometers range. Primary design goals are optical quality to exploit the 8 m telescope advantage and large spectral field to exploit the sensitivity advantage of a dispersive instrument with a large detector array. The basic instrument uses established technology; some components potentially leading to enhanced performance or additional capabilities are under development.

The Cassegrain focus of the 2nd unit telescope of ESO's VLT shall be equipped with a 10/20 micrometers camera spectrometer. This instrument shall be built by a consortium of institutes from ESO's member-states responsible for the final design. Still rather detailed internal studies were required to assess the overall scope of work, the repercussions on the telescope design and the required infrastructure at ESO. The internal studies have resulted in a multimode instrument allowing for diffraction limited imaging with variable magnification at 10/20 micrometers , low-, medium- plus potentially high-resolution long slit spectroscopy (approaching or exceeding (lambda) divided by (Delta) (lambda) approximately equals 50000). The optical design allows to take advantage of the rapid evolution in the field of detectors. Novel design features are an exchangeable entrance window, an anamorphic beam expansion and potentially the use of immersion gratings. At the La Silla observatory TIMMI, a small 10 micrometers camera/spectrometer for the 3.6 m telescope (built by the Service d'Astrophysique, CEN- Saclay, France) is in operation to allow both ESO and its community to gain practical experience in astronomy in the 10 micrometers atmospheric window. This instrument is currently equipped with a 64x64 element Ga:Si array. A 128x196 element array is presently in development at Leti/LIR of Grenoble, France, which may be used to upgrade ESO's current observing capabilities. Spectroscopy in TIMMI utilizes Germanium grisms machined via anisotropic etching. This manufacturing technology may also serve to fabricate immersion gratings from high index materials.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Adaptive optics is one of the main features of the Very Large Telescope of the European Southern Observatory (ESO). Use of the large telescopes for high spatial resolution imaging, high spectral resolution spectroscopy and astronomical spatial interferometry depends substantially on the availability of adaptive optics, which allows diffraction limited imaging for each individual telescope in the near infrared wavelength range (2.2 to 5 microns) and partial correction of atmospheric distortions towards the visible wavelength range. Recent decisions from ESO Council to postpone the VLT interferometer and the associated adaptive optics and Coude beams has led us to study the implementation of this capability at the Nasmyth focus. We present here the first preliminary conceptual design which follows the outline of the Coude configuration from the performance point of view. Some scientific pre-studies, such as sky coverage evaluation and statistics of observable objects are summarized. Finally an analysis of the different sources of image degradation after the adaptive optics correction, are described.

A recent paper by Bhatia (1995) suggest from calculations based on the optical geometry of the NTT that the zero-coma condition is a necessary but insufficient condition for the alignment of modern telescopes and that analysis of separate decenter effects is necessary to cope with decentering astigmatism aberrations near the field c enter. We show here that, while Bhatia's calculations are quite correct, their basis shows a misunderstanding of how the NTT was actually aligned and that this "passive" alignment was sufficiently good that the decentering astigmatism effects he indicates were negligible. More dangerous are the wide-field effects of decentering astigmatism discussed by McLeod (1996). However, we show that these effects, linear with field, are also negligible with the NTT alignment quality achieved, provided the correct effective shift of the astigmatic field center is allowed for int he active correction software. This is of great importance in the NTT because the image analyser operates at the edge of the field and the correct field astigmatism must be subtracted to give the necessary active correction at the mechanical field center. This approach is valid for the technical use of the edge field of an aplanatic (RC) telescope limited by field astigmatism. Decentering astigmatism will be much more critical at the field edge for anastigmatic telescopes is a wide field is also used for astronomical observation.

A spectrograph with collimator compensated camera chromatism (4C) is presented. It has the following advantages compared to classical designs: The camera is small, inexpensive, and can be easily exchanged. It is based on standard materials. Large aspheres are not needed for the lenses. It appears that there are no problems to scale up the design for beam diameters well over 0.5 m. The instrument is efficient and there is no vignetting. The long slit allows a large degree of spatial multiplexing.

In the course of a systematic analysis of various design philosophies aimed at achieving high optical throughput low resolution spectrometers for telescopes in the range of 2-4 meters, two distinct optical designs were established. The first is optimised for a telescope prime focus having a fast F/ratio, and is based on a concave grating whose aberrations are corrected by 2 or 3 off-axis lenses. The second system is a focal reducer, utilizing lenses and transmission gratings only. The use of a particular glass type having an extremely low dispersion permits excellent correction of various aberrations over a wide spectral range. Both designs provide a two-dimensionally corrected field typical of present day CCD array formats. These designs are highly suitable for long slit or field spectroscopy and offer the possibility of rapid switching to direct imaging mode.

The MAD demonstrator performed on-sky observations at VLT telescope for validating Ground-Layer, Laser Tomography and Multi-Conjugate Adaptive Optics correction. Here we present the results obtained on the sky and in laboratory for Star Oriented mode. Article not available.