Fabio Tenegi

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.

EMIR: the GTC NIR multi-object imager-spectrograph

In this contribution we review the overall features of EMIR, the NIR multiobject spectrograph of the GTC. EMIR is at present in the middle of the PD phase and will be one of the first common user instruments for the GTC, the 10 meter telescope under construction by GRANTECAN at the Roque de los Muchachos Observatory (Canary Islands, Spain). EMIR is being built by a Consortium of Spanish, French and British institutes led by the IAC. EMIR is designed to realize one of the central goals of 10m class telescopes, allowing observers to obtain spectra for large numbers of faint sources in an time-efficient manner. EMIR is primarily designed to be operated as a MOS in the K band, but offers a wide range of observing modes, including imaging and spectroscopy, both long slit and multiobject, in the wavelength range 0.9 to 2.5 μm. The present status of development, expected performances and schedule are described and discussed. This project is funded by GRANTECAN and the Plan Nacional de Astronomía y Astrofísica (National Plan for Astronomy and Astrophysics, Spain).

Structural and thermal analysis of EMIR

This paper shows the different design concepts and techniques employed in the structural and thermal analysis of EMIR (Espectrografo Multiobjeto Infrarrojo), nowadays under development at the Instituto de Astrofisica de Canarias.

EMIR mechanical design status

EMIR is the NIR multi-object imager and spectrograph for the GTC (Gran Telescopio Canarias). The instrument PDR phase was held successfully in March 2003, and we are at present in the middle of the ADR (Advanced Design Phase) during which a number of mechanical concepts will be tested on development prototypes to ensure the feasibility of the PDR proposed design. This presentation contains a technical description of the mechanical design of the instrument, as well as the prototypes development. The mechanical design is essentially built around the optical layout by providing an optical bench for mounting the optomechanics, the mechanisms and the detector, all this inside a custom-designed vacuum vessel and with the corresponding cooling system. One of its main design features is the use of a cryogenic reconfigurable slit mechanism to generate a multi-slit configuration, a long slit or an imaging aperture at the telescope focal plane. This feature will permit to maintain the instrument in operation conditions for a long time and take advantages in both a classically scheduled and a queued service observing schemes

Status of the EMIR mechanical system

EMIR is the NIR multi-object imager and spectrograph for the GTC (Gran Telescopio Canarias). The instrument ADR (Advanced Design Review) was held successfully in March 2006. During the AD phase, a number of mechanical concepts were tested on development prototypes to ensure the feasibility of the PDR proposed designs. This presentation contains an overview of the current mechanical status of the instrument, as well as the prototypes development. It contains the prototype tests results of the collimator first lens barrel, the support trusses, the grisms wheel and the demonstration programme for the cryogenic reconfigurable slit mechanism.

EMIR: THE GTC NIR MULTI-OBJECT IMAGER-SPECTROGRAPH

no nal global y el desempe~ de EMIR, el espectr ografo para objetos m ultiples del NIR del GTC, como tambi en el plan para su aplicaci on cient ca inicial. EMIR, actualmente en sus fases nales, ser a uno de los primeros instrumentos para usuarios del GTC, el telescopio de 10 metros en construcci on por GRANTECAN en el Observatorio del Roque de los Muchachos (Islas Canarias, Espa~ A EMIR lo construye un consorcio de institutos espa~ y franceses conducido por IAC. EMIR est a dise~ para llevar a cabo uno de los objetivos centrales de los telescopios de la clase de 10 metros, lo que permitir a a los observadores obtener espectros de gran n umero de objetos d ebiles de una manera ecien te en cuanto al tiempo. EMIR est a dise~ para ser operado primariamente como un MOS en la banda K, pero ofrece adem as un amplio rango de modos observacionales, incluido imagen y espectroscop a, tanto de rendija larga como de objetos m ultiples, en el rango de longitudes de onda de 0.9 a 2.5 m. Se encuentra equipado con dos subsistemas novedosos: una m ascara de rendijas m ultiples rob otica recongurable y elementos dispersivos formados por una combinaci on de rejilla de difracci on y prismas convencionales de alta calidad, ambos localizados en el coraz on del instrumento. Se describe y discute el estado actual de desarrollo, el desempe~ esperado, el calendario y los planes de aplicaci on cient ca. Este proyecto est a nanciado mayormente por GRANTECAN y el Plan Nacional de Astronom a y Astrof sica de Espa~ na.

Status of the GTC adaptive optics: integration in laboratory

Since the beginning of the development of the Gran Telescopio Canarias (GTC), an Adaptive Optics (AO) system was considered necessary to exploit the full diffraction-limited potential of the telescope. The GTC AO system designed during the last years is based on a single deformable mirror conjugated to the telescope pupil, and a Shack-Hartmann wavefront sensor with 20 x 20 subapertures, using an OCAM2 camera. The GTCAO system will provide a corrected beam with a Strehl Ratio (SR) of 0.65 in K-band with bright natural guide stars. Most of the subsystems have been manufactured and delivered. The upgrade for the operation with a Laser Guide Star (LGS) system has been recently approved. The present status of the GTCAO system, currently in its laboratory integration phase, is summarized in this paper.

ESPRESSO optical bench: from mind to reality

ESPRESSO [1] is a high-resolution spectrograph under development for the VLT telescope. In general, the Optical Bench (OB) structure can be considered as a 3D one, conformed by welding thin plates of Structural Steel (St-52) with a nickelplated surface treatment, combined for getting maximum stiffness and minimum weight, that will be finally re-machined to get stringent geometrical and dimensional tolerances at I/Fs positions. TIG conventional welding procedure has been selected to minimize the cost and facilitate the own welding process. This solution follows the inheritance from HARPS [2] due to its success to achieve the required performance for the bench. This paper contains an overview of the whole process of designing and manufacturing the Optical Bench of ESPRESSO, from the very first beginning with the specifications to the current status of the bench with its integration on the Spectrograph (including the Finite Element Models and the delivery of the final structure by the supplier) and lessons learned.

Test results: EMIR optomechanics

EMIR is a NIR multiobject spectrograph with imaging capabilities to be used at the GTC. The first collimator lens in EMIR, made of Fused Silica, has an outer diameter of 490 mm, and a weight of 265 N, which make it one of the largest Fused Silica lenses ever mounted to work under cryogenic conditions. The results of the various tests being done at the IAC (with two different lens dummies) in order to validate a mounting design concept for this lens, are presented here. The radial support concept tested consists of three contact areas around the lens, one of which is a PTFE block, preloaded by coil springs and the other two are fixed supports made of Aluminum and PTFE, dimensioned in order to keep lens centered both at room temperature and under operation conditions.

Mechanics of LIRIS (long-slit intermediate-resolution infrared spectrograph) at first commissioning

LIRIS is a near-infrared intermediate resolution spectrograph with added capabilities for multi-slit, imaging, coronography, and polarimetry, developed by the Instituto de Astrofisica de Canarias (IAC). It will be a common user instrument for the Cassegrain focus of the William Herschel Telescope (WHT) at the Roque de los Muchachos Observatory in La Palma. At its first commissioning, that was held in February 2003, the functionality of the mechanisms (entrance wheel, central wheels and camera wheel) under variable orientation of the telescope was verified, and no thermal nor structural problems arose. The functionality of the mechanical interface with telescope (allows for up to 5 mm of lateral displacements in the attachment plane), of the LIRIS handling trolley, of the transport equipment and of all the equipments used in the integration was also checked. For the second commissioning of LIRIS, which has been held in March 2004, some modifications have been done. The results of both commissionings were satisfactory.