Marco Riva

The field stabilization and adaptive optics mirrors for the European Extremaly Large Telescope

A 42 meters telescope does require adaptive optics to provide few milli arcseconds resolution images. In the current design of the E-ELT, M4 provides adaptive correction while M5 is the field stabilization mirror. Both mirrors have an essential role in the E-ELT telescope strategy since they do not only correct for atmospheric turbulence but have also to cancel part of telescope wind shaking and static aberrations. Both mirrors specifications have been defined to avoid requesting over constrained requirements in term of stroke, speed and guide stars magnitude. Technical specifications and technological issues are discussed in this article. Critical aspects and roadmap to assess the feasibility of such mirrors are outlined.

EELT-HIRES the high-resolution spectrograph for the E-ELT

The first generation of E-ELT instruments will include an optic-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long phase A study for EELT-HIRES has just started and will be performed by a consortium composed of institutes and organisations from Brazil, Chile, Denmark, France, Germany, Italy, Poland, Portugal, Spain, Sweden, Switzerland and United Kingdom. In this paper we describe the science goals and the preliminary technical concept for EELT-HIRES which will be developed during the phase A, as well as its planned development and consortium organisation during the study.

Preparing for the phase B of the E-ELT MCAO module project

The Multi-Conjugate Adaptive Optics module for the European Extremely Large Telescope has been designed to achieve uniform compensation of the atmospheric turbulence effects on a wide field of view in the near infrared. The design realized in the Phase A of the project is undergoing major revision in order to define a robust baseline in view of the next phases of the project. An overview of the on-going activities is presented.

Euclid near-infrared spectrophotometer instrument concept at the end of the phase A study

The Euclid mission objective is to map the geometry of the dark Universe by investigating the distance-redshift relationship and the evolution of cosmic structures. The NISP (Near Infrared Spectro-Photometer) is one of the two Euclid instruments operating in the near-IR spectral region (0.9-2μm). The instrument is composed of: - a cold (140K) optomechanical subsystem constituted by a SiC structure, an optical assembly, a filter wheel mechanism, a grism wheel mechanism, a calibration unit and a thermal control - a detection subsystem based on a mosaic of 16 Teledyne HAWAII2RG 2.4μm. The detection subsystem is mounted on the optomechanical subsystem structure - a warm electronic subsystem (280K) composed of a data processing / detector control unit and of an instrument control unit. This presentation will describe the architecture of the instrument, the expected performance and the technological key challenges. This paper is presented on behalf of the Euclid Consortium.

The common path of SOXS (Son of X-Shooter)

Son of X-Shooter (SOXS) will be a high-efficiency spectrograph with a mean Resolution-Slit product of 4500 (goal 5000) over the entire band capable of simultaneously observing the complete spectral range 350-2000 nm. It consists of three scientific arms (the UV-VIS Spectrograph, the NIR Spectrograph and the Acquisition Camera) connected by the Common Path system to the NTT and the Calibration Unit. The Common Path is the backbone of the instrument and the interface to the NTT Nasmyth focus flange. The light coming from the focus of the telescope is split by the common path optics into the two different optical paths in order to feed the two spectrographs and the acquisition camera. The instrument project went through the Preliminary Design Review in 2017 and is currently in Final Design Phase (with FDR in July 2018). This paper outlines the status of the Common Path system and is accompanied by a series of contributions describing the SOXS design and properties after the instrument Preliminary Design Review.

The REMIR cryogenics restyling

REMIR is the NIR camera of the automatic REM (Rapid Eye Mount) Telescope located at ESO-La Silla Observatory (Chile) and dedicated to monitor the afterglow of Gamma Ray Burst events. During the last two years, the REMIR camera went through a series of cryogenics problems, due to the bad functioning of the Leybold cryocooler Polar SC7. Since we were unable to reach with Leybold for a diagnosis and a solution for such failures, we were forced to change drastically the cryogenics of REMIR, going from cryocooler to LN2: we adopted an ad-hoc modified Continuous Flow Cryostat, a cryogenics system developed by ESO and extensively used in ESO instrumentation, which main characteristic is that the LN2 vessel is separated from the cryostat, allowing a greater LN2 tank, then really improving the hold time. In this paper we report the details and results of this operation.

The assembly integration and test activities for the new SOXS instrument at NTT

Son Of X-Shooter (SOXS) is the new instrument for the ESO 3.5 m New Technology Telescope (NTT) in La Silla site (Chile) devised for the spectroscopic follow-up of transient sources. SOXS is composed by two medium resolution spectrographs able to cover the 350-2000 nm interval. An Acquisition Camera will provide a light imaging capability in the visible band. We present the procedure foreseen for the Assembly, Integration and Test activities (AIT) of SOXS that will be carried out at sub-systems level at various consortium partner premises and at system level both in Europe and Chile.

The mechanical design of SOXS for the NTT

SOXS (Son of X-shooter) is a wide band, medium resolution spectrograph for the ESO NTT with a first light expected in early 2021. The instrument will be composed by five semi-independent subsystems: a pre-slit Common Path (CP), an Acquisition Camera (AC), a Calibration Unit (CU), the NIR spectrograph, and the UV-VIS spectrograph. In this paper, we present the mechanical design of the subsystems, the kinematic mounts developed to simplify the final integration procedure and the maintenance. The concept of the CP and NIR optomechanical mounts developed for a simple pre- alignment procedure and for the thermal compensation of reflective and refractive elements will be shown.

The acquisition camera system for SOXS at NTT

SOXS (Son of X-Shooter) will be the new medium resolution (R~4500 for a 1 arcsec slit), high-efficiency, wide band spectrograph for the ESO-NTT telescope on La Silla. It will be able to cover simultaneously optical and NIR bands (350-2000nm) using two different arms and a pre-slit Common Path feeding system. SOXS will provide an unique facility to follow up any kind of transient event with the best possible response time in addition to high efficiency and availability. Furthermore, a Calibration Unit and an Acquisition Camera System with all the necessary relay optics will be connected to the Common Path sub-system. The Acquisition Camera, working in optical regime, will be primarily focused on target acquisition and secondary guiding, but will also provide an imaging mode for scientific photometry. In this work we give an overview of the Acquisition Camera System for SOXS with all the different functionalities. The optical and mechanical design of the system are also presented together with the preliminary performances in terms of optical quality, throughput, magnitude limits and photometric properties.

Optical design of the SOXS spectrograph for ESO NTT

An overview of the optical design for the SOXS spectrograph is presented. SOXS (Son Of X-Shooter) is the new wideband, medium resolution (R>4500) spectrograph for the ESO 3.58m NTT telescope expected to start observations in 2021 at La Silla. The spectroscopic capabilities of SOXS are assured by two different arms. The UV-VIS (350-850 nm) arm is based on a novel concept that adopts the use of 4 ion-etched high efficiency transmission gratings. The NIR (800- 2000 nm) arm adopts the ‘4C’ design (Collimator Correction of Camera Chromatism) successfully applied in X-Shooter. Other optical sub-systems are the imaging Acquisition Camera, the Calibration Unit and a pre-slit Common Path. We describe the optical design of the five sub-systems and report their performance in terms of spectral format, throughput and optical quality. This work is part of a series of contributions1-9 describing the SOXS design and properties as it is about to face the Final Design Review.