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Multi-conjugated adaptive optics (MCAO) is essential for performing astrometry with the Extremely Large Telescope (ELT). Unlike most of the 8-m class telescopes, the ELT will be a fully adaptive telescope, and a significant portion of the adaptive optics (AO) dynamic range will be depleted by the correction and stabilization of the telescope aberrations and instabilities. MCAO systems are of particular interest for ground-based astrometry since they stabilize the low-order field distortions and transient plate scale instabilities, which originate from the telescope and in the instrument. All instruments have several optical elements relatively far away from the pupil that can potentially challenge the astrometric precision of the observations with their residual mid-spatial frequencies errors. Using a combined simulation of ray tracing and AO numerical codes, we assess the impact of these systematic errors at different field-of-view (FoV) scales and fitting scenarios. The distortions have been assessed at different sky position angles (PA) and indicate that over large FoVs only small PA ranges (±1 deg to 3 deg) are accessible with astrometric residuals ≤50 μas. A full compliance with the astrometric requirement, at any PA, is achievable for 2 arc sec2 FoV patches already with a third-order polynomial. The natural partition of the optical system into three segments, i.e., the ELT, the MAORY MCAO module, and the MICADO instrument, resembles a splitting of the astrometric problem into the three subsystems that are characterized by different distortion amplitudes and calibration strategies. The result is a family portrait of the different optical segments with their specifications, dynamic motions, conjugation height, and AO correctability, leading to tracing their role in the bigger puzzle of the 50-μas as astrometric endeavor.

Testicular cancers are classified in germ cell and non-germ cell tumors, as well as, liposarcomas. We report the case of a patient with a large testicular liposarcoma, submitted to surgical treatment with excision of scrotal pouch and segment of the spermatic cord, and the left testicle, showing a good evolution. This report presents one of the first cases of a sclerosing variant of well-differentiated testicular liposarcoma, large in size and with no association with another cancer. Due to their location, the diagnosis is difficult and unusual. Complete tumor resection and regular medical follow-up show a good prognosis, less recurrence, and little cellular differentiation.

The different optical designs that locate the optical elements in the MAORY volume impose a different strategy in the design definition of the optomechanics. Considering the different types of elements in the optical design the optomechanics must satisfy the requirement in terms of stiffness, mass and provide a compensating effect respect to the thermal breathing of the materials. In the paper are presented the solutions taken and the mounts working principle. In particular, the aspects that underline and analysed in the simulation are: 1) The behaviour of the mounts in earthquake condition and in thermal survivor condition that means twenty degrees of variation of temperature. 2) The operational condition, the deformation induced in the optical surface due to the gravity, the alignment, and a variation of temperature. 3) The modal analysis of the structure.

The Multi Conjugate Adaptive Optics RelaY (MAORY) is the Multi-Conjugated Adaptive Optics (MCAO) module for the European Extremely Large Telescope (ELT). MAORY is one of the ELT first light instruments, designed to feed the Near Infrared Red (NIR) camera MICADO with both MCAO and Single-Conjugated AO (SCAO) operation modes. The optical configuration provides a one to one image of telescope focal surface on the MICADO focal surface (with the additional capability for a second port dedicated to a future instrument), and allows the implementation of two deformable mirrors together with the Laser Guide Star (LGS) and Natural Guide Star (NGS) channels for wavefront sensing and tomographic reconstruction. In this paper we present the status of the optical configuration in the Preliminary Design Review (PDR) framework for the main path optics and the analyses results on the expected optical performance.

MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). The instrument provides imaging, astrometric, spectroscopic and coronographic observing modes. MICADO will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multi-conjugate Adaptive Optics RelaY (MAORY). The instrument will provide a narrow (19′′) and a wide (51”) Field of View. MICADO can operate in the so-called stand-alone mode in the absence of MAORY with the SCAO correction alone. Here, we present the opto-mechanical design of the Relay Optics (RO), the optical system relaying the ELT focal plane to an accessible position for MICADO using the SCAO-only stand-alone observing mode. The RO consists of an optical bench made of carbon fiber reinforced plastic (CFRP), an optical assembly made of three flat mirrors with motorized piston-tip-tilt mounts and three additional powered mirrors of up to ~500 mm in diameter, the MICADO calibration assembly, and a cover to protect all opto-mechanical components on top of the bench. A 9-point whiffletree support, combined with a thermal compensation system is implemented for the critical mirrors. The static and the dynamic performance of the MICADO RO are investigated through a detailed Finite Element Model (FEM), the results are combined with a Zernike basis representation of the mirror surface deformations performed in Zemax for assessing the optical performance.

MAORY is a post-focal adaptive optics module that forms part of the first light instrument suite for the ELT. The main function of MAORY is to relay the light beam from the ELT focal plane to the client instrument while compensating the effects of the atmospheric turbulence and other disturbances affecting the wavefront from the scientific sources of interest.

MAORY (Multi Conjugate Adaptive Optics RelaY) is one of the four instruments for the ELT (Extremely Large Telescope) approved for construction. It is an adaptive optics module able to compensate the wavefront disturbances affecting the scientific observations, achieving high strehl ratio and high sky coverage. MAORY will be installed on the straight-through port of the telescope Nasmyth platform and shall re-image the telescope focal plane to MICADO (the first light imager of the ELT) and in a future second instrument port. A general overview of the present status of the mechanical design of the Main structure is given in this paper.

MCAO is essential to perform astrometry with the Extremely Large Telescope (ELT). Differently from the 8m class telescopes, the ELT will be a fully adaptive telescope, and a significant portion of the Adaptive Optics (AO) dynamic range will be absorbed by the correction and stabilization of the telescope aberrations and instabilities. Of particular interest for the ground-based astrometry is the use of Multi-Conjugated AO systems that allow to stabilize the low order field distortions against the transient plate scale instabilities of different origin occurring at the telescope and in the instrument. The instruments have several optical elements relatively far away from the pupil that can potentially challenge the astrometric precision of the observations with their residual mid-spatial frequencies errors. Using a combined simulation of ray tracing and AO numerical codes we assess the impact of these systematic errors at different field of view scales and fitting scenarios. The distortions have been assessed at different sky Position Angles (PA) and indicate that over large field of views only small PA ranges (±1°-3°) are accessible with astrometric residuals 50 µas. A full compliance, at any PA is achievable for 2 arcsec2 FoV patches already with a 3rd order polynomial. The natural partition of the optical system in three segments, ELT-MAORY-MICADO, respectively telescope, MCAO module and instrument, resembles also a splitting of the astrometric problem in the three subsystems that are characterized by different distortion amplitudes and calibration strategies. The result is a family portrait of the different optical segments with their prescription, dynamic motions, conjugation height and AO correctability, leading to trace their role in the bigger puzzle of the 50 μas astrometric endeavor.

MAORY (Multi-conjugate Adaptive Optics RelaY) is one of the first light instruments for the ESO Extremely Large Telescope (ELT). It will be firstly used by MICADO (Multi-AO Imaging CamerA for Deep Observations), a near-infrared high-angular resolution imager, to compensate aberrations and provide highStrehl images within a 53”×53” Field of View (FoV). The complexity of MAORY requires calibration functionalities for both the AIV (Assembly-Integration-Verification) and the operational phase. The Calibration Unit (CU), providing suitable light sources, both Natural Guide Stars (NGS) and Laser Guide Stars (LGS), will enable MAORY to run calibration templates as well as verification and test procedures, in standalone mode, drastically reducing the amount of required night-time for such operations. An overview of the instrument, the current status of the design and the main challenges to face in the future are here presented.

The paper reports an overview of the preliminary optical design for the MICADO Relay Optics (RO) to enable early science observations of the instrument at the Extremely Large Telescope (ELT) with single-conjugate adaptive optics (SCAO). MICADO, the Multi-AO Imaging Camera for Deep Observations, is a first light imager, astrometric camera and spectrograph operating between 0.8 µm and 2.4 µm. The RO are based on a six mirror (6M) optical assembly that relays the telescope focal plane to an accessible position for the MICADO cryostat. The system includes three powered mirrors in a three-mirror-anastigmat configuration and three piston and tip- tilt flat mirrors for the alignment and the beam folding at the interfaces with the ELT and MICADO. This design represents an interesting example of optical performance optimization to achieve high performances optics both for the direct imaging channel and the pupil interface towards MICADO and the SCAO. The RO performances are analyzed and verified at a design level showing the compliance with the requirement specifications and the reliability of the design is assessed with an extended tolerance study and a minimization of the vignetting factor at the MICADO cold stop. The manuscript also contains a demonstration of the optical alignability of a 6M system in terms of pupil and focal plane steering that are essential to cope with the interface tolerances of the next generation of instrument at the foci of the extremely large telescopes.

Despite the ability to remove the degradation introduced by the atmospheric turbulence has dramatically improved in the last years, in particular for NGS based systems, sky-coverage is one of the major issues for ground-based observations with current and future AO-assisted telescopes. Although new LGS WFS concepts have been recently proposed to strongly improve performances, the use of LGS, to increase the limited sky-coverage, still remains a significant bottleneck, severely limiting the exploitation of the enormous capabilities of current and already planned AO instrumentation on the 8-10m class telescopes and the upcoming ELTs. The progressive advancement of AO and the advent of CubeSat technologies, have led to the possibility of providing the largest ground-based AO facilities with suitable Satellite Guide Stars (SGS) as reference, to overcome the sky-coverage problem and achieve unprecedented scientific results. This perspective has induced numerous research institutes around the world to collaborate and to propose new ambitious space programs. The Ground-based adaptive optics Observations with Orbiting Nanosatellite (GO-ON) mission aims to design, develop and launch a CubeSat pathfinder, to assist astronomical observations at the Large Binocular Telescope (LBT). This mission will demonstrate, for the first time, the readiness of space and ground-based technologies and validate this new paradigm for future scientific programs with the ELTs, enabling transformative science across many fields of astrophysics.

We report on the first detection of very high-energy (VHE) gamma-ray emission from the Crab Nebula by a Cherenkov telescope in dual-mirror Schwarzschild-Couder (SC) configuration. The result has been achieved by means of the 4 m size ASTRI-Horn telescope, operated on Mt. Etna (Italy) and developed in the context of the Cherenkov Telescope Array Observatory preparatory phase. The dual-mirror SC design is aplanatic and characterized by a small plate scale, allowing us to implement large field of view cameras with small-size pixel sensors and a high compactness. The curved focal plane of the ASTRI camera is covered by silicon photo-multipliers (SiPMs), managed by an unconventional front-end electronics based on a customized peak-sensing detector mode. The system includes internal and external calibration systems, hardware and software for control and acquisition, and the complete data archiving and processing chain. The observations of the Crab Nebula were carried out in December 2018, during the telescope verification phase, for a total observation time (after data selection) of 24.4 h, equally divided into on- and off-axis source exposure. The camera system was still under commissioning and its functionality was not yet completely exploited. Furthermore, due to recent eruptions of the Etna Volcano, the mirror reflection efficiency was reduced. Nevertheless, the observations led to the detection of the source with a statistical significance of 5.4 sigma above an energy threshold of ~3 TeV. This result provides an important step towards the use of dual-mirror systems in Cherenkov gamma-ray astronomy. A pathfinder mini-array based on nine large field-of-view ASTRI-like telescopes is under implementation., 6 pages, 2 figures

The achievement of microarcsecond relative astrometry in the near- infrared, with ground-based extremely large telescopes (ELTs) requires an extremely careful calibration strategy. In this paper we address the removal of optical distortions originating from the ELT’s first light instrument MICADO and its adaptive optics system MAORY by means of a Warm Astrometric calibration Mask (WAM). The results of the test campaign on small spatial scales (1.5 mm) of a prototype mask has confirmed the manufacturing precision down to ∼50 nm/1 mm scale, leading to a relative precision of δσ ∼ 5 · 10−5. The assessed manufacturing precision indicates that an astrometric relative precision of δ σ ∼ 5\cdot {10}-5=\tfrac{50 μ {as}}{1\prime\prime }, corresponding to the MICADO astrometric requirement, is in principle achievable, reaching microarcsecond near-infrared astrometry on an ELT. The impact of ∼20 nm, (peak to valley) error residuals on position of the pinholes of the mask is tolerable at a calibration level as confirmed by ray tracing simulations of realistic MICADO distortion patterns affected by mid spatial frequencies (MSFs) residuals. Here we demonstrate that the MICADO astrometric precision of 50 μas over 1″ field of view is also achievable in the presence of a MSFs pattern and manufacturing errors of the WAM, found by fitting the distorted WAM pattern seen through the instrument with a 10th order Legendre polynomial.

The paper describes the preliminary design of the MICADO calibration assembly. MICADO, the Multi-AO Imaging CAmera for Deep Observations, is targeted to be one of the first light instruments of the Extremely Large Telescope (ELT) and it will embrace imaging, spectroscopic and astrometric capabilities including their calibration. The astrometric requirements are particularly ambitious aiming for ~ 50 μas differential precision within and between single epochs. The MICADO Calibration Assembly (MCA) shall deliver flat-field, wavelength and astrometric calibration and it will support the instrument alignment to the Single-Conjugate Adaptive Optics wavefront sensor. After a complete overview of the MCA subsystems, their functionalities, design and status, we will concentrate on the ongoing prototype testing of the most challenging components. Particular emphasis is put on the development and test of the Warm Astrometric Mask (WAM) for the calibration of the optical distortions within MICADO and MAORY, the multiconjugate AO module.

The paper discusses an assessment study about the impact of the distortions on the astrometric observations with the Extremely Large Telescope originated from the optics positioning errors and telescope instabilities. Optical simulations combined with Monte Carlo approach reproducing typical inferred opto-mechanical and dynamical instabilities, show RMS distortions between $\sim$ 0.1-5 mas over 1 arcmin field of view. Over minutes timescales the plate scale variations from ELT-M2 caused by wind disturbances and gravity flexures and the field rotation from ELT-M4-M5 induce distortions and PSF jitter at the edge of 1 arcmin FoV (radius 35 arcsec) up to $\sim$ 5 mas comparable to the diffraction-limited PSF size $FWHM_H = 8.5$ mas. The RMS distortions inherent to the ELT design are confined to the 1$^{st}$-3$^{rd}$ order and reduce to an astrometric RMS residual post fit of $\sim$ 10-20 $\mu as$ for higher order terms. In this paper, we study which calibration effort has to be undertaken to reach an astrometric stability close to this level of higher order residuals. The amplitude and timescales of the assumed telescope tolerances indicate the need for frequent on-sky calibrations and MCAO stabilization of the plate scale to enable astrometric observations with ELT at the level of $\leq 50 \mu as$, which is one of the core science missions for the ELT / MICADO instrument.

Highly reddened type Ia Supernovae (SNe Ia) with low total-to-selective visual extinction ratio values, $R_V$, also show peculiar linear polarization wavelength dependencies with peak polarizations at short wavelengths ($\lambda_{max} \lesssim 0.4 \mu m$). It is not clear why sightlines to SNe Ia display such different continuum polarization profiles from interstellar sightlines in the Milky Way with similar $R_V$ values. We investigate polarization profiles of a sample of Galactic stars with low $R_V$ values, along anomalous extinction sightlines, with the aim to find similarities to the polarization profiles that we observe in SN Ia sightlines. We undertook spectropolarimetry of 14 stars, and used archival data for three additional stars, and run dust extinction and polarization simulations to infer a simple dust model that can reproduce the observed extinction and polarization curves. Our sample of Galactic stars with low $R_V$ values and anomalous extinction sightlines displays normal polarization profiles with an average $\lambda_{max} \sim 0.53 {\mu m}$, and is consistent within 3$\sigma$ to a larger coherent sample of Galactic stars from literature. Despite the low $R_V$ values of dust towards the stars in our sample, the polarization curves do not show any similarity to the continuum polarization curves observed towards SNe Ia with low $R_V$ values. There is a correlation between the best-fit Serkowski parameters $K$ and $\lambda_{max}$, but we did not find any significant correlation between $R_V$ and $\lambda_{max}$. Our simulations show that the $K-\lambda_{max}$ relationship is an intrinsic property of polarization. Furthermore, we have shown that in order to reproduce polarization curves with normal $\lambda_{max}$ and low $R_V$ values, a population of large (a $\geq 0.1 \mu m$) interstellar silicate grains must be contained in the dust's composition., Comment: accepted for publication in A&A

MICADO will enable the ELT to perform diffraction limited near-infrared observations at first light. The instrument's capabilities focus on imaging (including astrometric and high contrast) as well as single object spectroscopy. This contribution looks at how requirements from the observing modes have driven the instrument design and functionality. Using examples from specific science cases, and making use of the data simulation tool, an outline is presented of what we can expect the instrument to achieve., Comment: Proc SPIE 10702. SPIE's copyright notice: "Copyright 2018 Society of PhotoOptical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited."

White light interferometry, also known as low-coherence interferometry, is a mature technique used in metrology to measure 3D surface morphology at sub-micrometric scale. This technique is used in many fields of applications, such as optical qualification tests, surface metrology, medicine and others. We present here a new set-up able to measure the distance of an object with sub-micrometric accuracy and a depth of field (depth range) of some millimeters. The instrument is useful to measure thermo-mechanical deformations as well as longitudinal optical alignments. The set-up does not present any moving part inside and then it may be fruitfully exploited, avoiding a possible point of failure, for space instrumentation. It may be useful, for example, to measure mechanical mounting or truss deformations or to control in-situ optical alignment.

White light interferometry is largerly used for measure glass optical thickness with sub-micrometric accuracy. Usually one of the interferometer arm is moving in order to scan, along the optical axis, the point-surface under test. We show here an alternative set-up, where the reference wavefront is spatially dispersed and no moving part is necessary inside the interferometer. A bidimensional image sensor is used for sample the spatially-dispersed interferogram and the depth information of a transparent glass window is performed in a single shot, i. e. without scanning any system. The interometer is useful for measure optical thickness up to many millimeter without using any moving parts. A prototype for measure up to 1 mm of optical thickness has been built and tested and the results are shown here.

The Cherenkov Telescope Array (CTA) represents the most advanced facility designed for Cherenkov Astronomy. ASTRI SST-2M has been developed as a demonstrator for the Small Size Telescope in the context of the upcoming CTA. Its main innovation consists in the optical layout which implements the Schwarzschild-Couder configuration and is fully validated for the first time. The ASTRI SST-2M optical system represents the first qualified example for two mirrors telescope for Cherenkov Astronomy. This configuration permits to (i) maintain a high optical quality across a large FoV (ii) de-magnify the plate scale, (iii) exploit new technological solutions for focal plane sensors. The goal of the paper is to present the optical qualification of the ASTRI SST-2M telescope. The qualification has been obtained measuring the PSF sizes generated in the focal plane at various distance from the optical axis. These values have been compared with the performances expected by design. After an introduction on the Gamma Astronomy from the ground, the optical design and how it has been implemented for ASTRI SST-2M is discussed. Moreover the description of the setup used to qualify the telescope over the full field of view is shown. We report the results of the first--light optical qualification. The required specification of a flat PSF of $\sim 10$ arcmin in a large field of view ~10 deg has been demonstrated. These results validate the design specifications, opening a new scenario for Cherenkov Gamma ray Astronomy and, in particular, for the detection of high energy (5 - 300 TeV) gamma rays and wide-field observations with CTA., Comment: 6 pages, 5 figures

The paper describes the developments towards an end-to-end optical model based on a commercial ray tracing software for studying the effects of the telescope and instrumental instabilities on the Multi-AO Imaging Camera for Deep Observations (MICADO). The primary goal and observing mode of MICADO is imaging, with a focus on relative astrometry with an accuracy of about 50 μas. To achieve this ambitious goal a careful examination of the possible random and systematic effects that can influence the astrometric accuracy is required. Here we concentrate on the perturbations coming from the different telescope and instrumental instabilities, mainly related to the static and dynamical perturbations of the European-Extremely Large Telescope (E-ELT) optics, the cold optics tolerances of the instrument and the intrinsic geometric distortions of both the systems. ESO developed an extended dataset of the E-ELT perturbations that are integrated inside the optical model of the telescope and the instrument relay optics for gathering the aberrated wavefronts. The wavefront error residuals are then propagated inside the system to check the distortions and their effects on the astrometric measurement at the instrument focal plane. From our analysis the dominating instrumental errors are: (i) the telescope induced distortions, in the order of => 100μas, that originate from the optics misalignments and presumably vary over

MICADO will equip the E-ELT with a first light capability for diffraction limited imaging at near-infrared wavelengths. The instrument's observing modes focus on various flavours of imaging, including astrometric, high contrast, and time resolved. There is also a single object spectroscopic mode optimised for wavelength coverage at moderately high resolution. This contribution provides an overview of the key functionality of the instrument, outlining the scientific rationale for its observing modes. The interface between MICADO and the adaptive optics system MAORY that feeds it is summarised. The design of the instrument is discussed, focussing on the optics and mechanisms inside the cryostat, together with a brief overview of the other key sub-systems., to appear in Ground-based and Airborne Instrumentation for Astronomy VI, eds. Evans C., Simard L., Takami H., Proc. SPIE vol. 9908 id 73; 2016

Dual-mirror Schwarzschild–Couder (SC) telescopes are based on highly aspherical optics, and they represent a novel design in the world of very high energy astrophysics. This work addresses the realization and the qualification of the secondary mirror for an SC telescope, named ASTRI, developed in the context of the Cherenkov Telescope Array Observatory. The discussion surveys the overall development from the early design concept to the final acceptance optical tests.

ASTRI SST-2M is an end-to-end prototype of Small Size class of Telescope proposed for the Cherenkov Telescope Array (CTA). Currently under completion at the Serra La Nave observing station (Mt. Etna, Catania, Italy), the ASTRI SST- 2M telescope is the first imaging dual-mirror telescope ever realized for Cherenkov telescopes. A mini-array of nine such telescopes will form the ASTRI mini-array proposed as a precursor and initial seed of CTA to be installed at the final CTA southern site. ASTRI SST-2M is equipped with an active optics system, controlling both the segmented primary mirror and the monolithic secondary mirror, which allows optical re-alignment during telescope slew. We describe the hardware and software solution that have been implemented for optics control and the models we developed for the system.

Cherenkov Telescopes are equipped with optical dishes of large diameter -- in general based on segmented mirrors -- with typical angular resolution of a few arc-minutes. To evaluate the mirror's quality specific metrological systems are required that possibly take into account the environmental conditions in which typically these telescopes operate (in open air without dome protection). For this purpose a new facility for the characterization of mirrors has been developed at the labs of the Osservatorio Astronomico di Brera of the Italian National Institute of Astrophysics. The facility allows the precise measurement of the radius of curvature and the distribution of the concentred light in terms of focused and scattered components and it works in open air. In this paper we describe the facility and report some examples of its measuring capabilities., Comment: 24 pages, 12 figures, 1 table, accepted for publication on September 26th 2015 in Nuclear Instruments and Methods in Physics Research Section A (NIM-A)

ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) SST-2M is an end-to-end prototype of Small Size class of Telescope for the Cherenkov Telescope Array. It will apply a dual mirror configuration to Imaging Atmospheric Cherenkov Telescopes. The 18 segments composing the primary mirror (diameter 4.3 m) are equipped with an active optics system enabling optical re-alignment during telescope slew. The secondary mirror (diameter 1.8 m) can be moved along three degrees of freedom to perform focus and tilt correc tions. We describe the kinematic model used to predict the system performance as well as the hardware and software de sign solution that will be implemented for optics control. Keywords: Imaging Atmospheric Cherenkov Telescope, CTA, ASTRI, gamma-rays, active optics 1. INTRODUCTION The dual-mirror ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) Small Size Telescope prototype, named ASTRI SST-2M, is a wide field of view Schwarzschild-Couder Cherenkov telescope developed within the Cherenkov Telescope Array (CTA) framework

ASTRI SST-2M is a prototype dual mirror Small Size class of Telescope for the Cherenkov Telescope Array (CTA). Its innovative design based on a Schwarzschild-Couder configuration will permit use Silicon Photo-multipliers as focalplane detectors. The dual mirror configuration is a challenge for the realization of both the primary and secondary. Accurate tests and characterization are mandatory to understand the behavior of the optical configuration, its limits and the possibility of improvements of the full CTA array. Moreover, optical alignment requires solutions and procedures that have not been used so far on Cherenkov telescopes. The aim of paper is to provide an analysis of these topics in the context of the ASTRI SST-2M telescope.

The next generation of imaging atmospheric Cherenkov telescopes will require the production of thousands of mirror segments; an unprecedented amount of optical surface. To accomplish this, the Italian Istituto Nazionale di AstroFisica (INAF) has recently developed a successful technique. This method, called glass cold-shaping, is mainly intended for the manufacturing of mirrors for optical systems with an angular resolution of a few arcminutes, intended to operate in extreme environments. Its principal mechanical features are very low weight and high rigidity of the resulting segments, and its cost and production time turn out to be very competitive as well. The process is based on the shaping of thin glass foils by means of forced bending at room temperature; a sandwich structure is then assembled for retaining the imposed shape. These mirrors are composted of commercial, off-the-shelf materials. In this contribution we give an overview of the latest results achieved in the manufacturing of the pre-production series of mirrors for the Medium Size and Small Size Telescopes of the Cherenkov Telescope Array observatory.

The Cherenkov Telescope Array (CTA) observatory will represent the next generation of Imaging Atmospheric Cherenkov Telescopes. Using a combination of large-, medium-, and small-scale telescopes (LST, MST, SST, respectively), it will explore the Very High Energy domain from a few tens of GeV up to few hundreds of TeV with unprecedented sensitivity, angular resolution and imaging quality. In this framework, the Italian ASTRI program, led by the Italian National Institute of Astrophysics (INAF), is currently developing a scientific and technological SST prototype named ASTRI SST-2M; a 4-meter class telescope, it will adopt an aplanatic, wide-field, double-reflection optical layout in a Schwarzschild-Couder configuration. In this contribution we give an overview of the technological solutions adopted for the ASTRI SST-2M prototype. In particular we focus on the manufacturing of the telescope structure and mirrors. We will also describe early results from tests.

The Cherenkov Telescope Array (CTA) observatory will represent the next generation of Imaging Atmospheric Cherenkov Telescope. Using a combination of large-, medium-, and small-scale telescopes (LST, MST, SST, respectively), it will explore the Very High Energy domain from a few tens of GeVup to about few hundreds of TeV with unprecedented sensitivity, angular resolution and imaging quality. In this framework, the Italian ASTRI program, led by the Italian National Institute of Astrophysics (INAF) developed a 4-meter class telescope, which will adopt an aplanatic, wide-field, double-reflection optical layout in a Schwarzschild- Couder configuration. Within this program INAF assigned to the consortium between Galbiati Group and EIE Group the construction, assembly and tests activities of the prototype named ASTRI SST-2M. On the basis of the lesson learnt from the prototype, other telescopes will be produced, starting from a re-design phase, in order to optimize performances and the overall costs and production schedule for the CTA-SST telescope. This paper will firstly give an overview of the concept for the SST prototype mount structure. In this contest, the technologies adopted for the design, manufacturing and tests of the entire system will be presented. Moreover, a specific focus on the challenges of the prototype and the strategies associated with it will be provided, in order to outline the near future performance goals for this type of Cherenkov telescopes employed for Gamma ray science.

The next generation of Imaging Atmospheric Cherenkov Telescope will explore the uppermost end of the Very High Energy domain up to about few hundreds of TeV with unprecedented sensitivity, angular resolution and imaging quality. To this end, the Italian National Institute of Astrophysics (INAF) is currently developing a scientific and technological telescope prototype for the implementation of the Cherenkov Telescope Array (CTA) observatory. The Italian ASTRI program foresees the full design, development, installation and calibration of a Small Size 4-meter class Telescope, adopting an aplanatic, wide-field, double-reflection optical layout in a Schwarzschild-Couder configuration. In this paper we discuss about the technological solutions adopted for the telescope and for the mirrors. In particular we focus on the structural and electro-mechanical design of the telescope, now under fabrication. The results on the optical performance derived from mirror prototypes are here described, too.

ASTRI is an Flagship Project led by the Italian National Institute of Astrophysics, INAF, strictly linked to the development of the ambitious Cherenkov Telescope Array, CTA. Primary goal of the ASTRI project is the design, production, installation and calibration of an end-to-end Small Size Telescope prototype, devoted to the investigation of the highest gamma-ray energy band, from a fraction of TeV up to 100 TeV and beyond. The telescope, named ASTRI SST-2M, is mainly characterized by an optical system in dual-mirror configuration and by a modular camera at the curved focal surface composed of a matrix of Silicon Photo-Multipliers photo-sensors. In this paper we present an overview of the mechanical, thermal and electrical concept design of the camera and of the related technological solutions adopted for the ASTRI SST-2M prototype.

La factibilidad de obtener productos agrícolas de calidad, irrigados con agua salina, hace necesario evaluar áreas periféricas al oasis irrigado para determinar su aptitud para el cultivo. El objetivo es articular diversas metodologías para cartografiar y evaluar unidades ecológicamente homogéneas en tierras marginales de Mendoza utilizando las comunidades vegetales como indicador. Se relevó un área piloto mediante procesamiento de imagen LANDSAT/TM y se analizó la vegetación, suelo y freática. Las unidades evaluadas y sus respectivos rangos de salinidad, en dS m-1, hasta 50 cm fueron: estepa de Heterostachys ritteriana, 91-83; matorral de Allenrolfea vaginata con H. ritteriana, 83-48; matorral abierto de A.vaginata con Prosopis strombulifera, 62-55; estepa abierta de Suaeda divaricata con Atriplex argentina, 52-83; matorral de S. divaricata con Lycium tenuispinosum, 40-43; bosquecillo abierto de Prosopis flexuosa, 37-26; matorral denso de Prosopis alpataco, 7-6. La concentración de sales solubles sobrepasa los niveles críticos tolerados por las plantas cultivadas. No se detectaron niveles freáticos en los primeros 15 m de profundidad. Se considera que los suelos tienen buen drenaje interno, por lo que pueden ser recuperados sin inversiones elevadas. Este enfoque metodológico mostró una buena correspondencia entre las comunidades vegetales, su expresión espectral y las condiciones de salinidad y drenaje del suelo. The feasibility to obtain quality agricul tural products, irrigated with saline water, makes it necessary to assess areas peripheral to the irrigated oasis in order to determine their suitability for cropping. The goal is to combine diverse methodologies for mapping and assessing ecologically homogeneous units in marginal lands of Mendoza, using plant communities as an indicator of these units. A pilot area was surveyed using LANDSAT/TM image processing, and vegetation, soil and water table were analysed. Assessed vegetation units and their respective salinity ranges (dS m-1), up to 50 cm depth, were: steppe of Heterostachys ritteriana, 91-83; shrubland of Allenrolfea vaginata with H. ritteriana, 83-48; open shrubland of A.vaginata con Prosopis strombulifera, 62-55; open steppe of Suaeda divaricata with Atriplex argentina, 52-83; shrubland of S. divaricata con Lycium tenuispinosum, 40-43; open woodland of Prosopis flexuosa, 37-26; dense shrubland of Prosopis alpataco, 7-6. The concentration of soluble salts exceeds the critical levels tolerated by cultivated plants. No water tables were detected within 15 m from the surface. It is considered that soils have good drainage conditions, so they can be recovered without high investment. This methodological approach showed good correspondence among plant communities, their spectral expression, and soil salinity and drainage conditions. Fil: Gonzalez Loyarte, Maria Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentina Fil: Gaviola, Silvia. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; Argentina Fil: Buk, Enrique Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Rodeghiero, Alfio Guido. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; Argentina Fil: Menenti Massimo. Consiglio Nazionale Delle Ricerche; Italia

La factibilidad de obtener productos agrí­colas de calidad, irrigados con agua salina, hace necesario evaluar áreas periféricas al oasis irrigado para determinar su aptitud para el cultivo. El objetivo es articular diversas metodologías para cartografiar y evaluar uni­dades ecológicamente homogéneas en tie­rras marginales de Mendoza utilizando las comunidades vegetales como indicador. Se relevó un área piloto mediante procesamien­to de imagen LANDSAT/TM y se analizó la vegetación, suelo y freática. Las unidades evaluadas y sus respectivos rangos de salinidad, en dS m-1, hasta 50 cm fueron: es­tepa de Heterostachys ritteriana, 91-83; ma­torral de Allenrolfea vaginata con H. ritteriana, 83-48; matorral abierto de A.vaginata con Prosopis strombulifera, 62-55; estepa abierta de Suaeda divaricata con Atriplex argentina, 52-83; matorral de S. divaricata con Lycium tenuispinosum, 40-43; bosquecillo abierto de Prosopis flexuosa, 37-26; matorral denso de Prosopis alpataco, 7-6. La concentración de sales solubles sobrepasa los niveles críticos tolerados por las plantas cultivadas. No se de­tectaron niveles freáticos en los primeros 15 m de profundidad. Se considera que los suelos tienen buen drenaje interno, por lo que pueden ser recuperados sin inversiones elevadas. Este enfoque metodológico mostró una buena co­rrespondencia entre las comunidades vegeta­les, su expresión espectral y las condiciones de salinidad y drenaje del suelo.