Simulations of ELT-GMCAO performance for deep field observations

The Global-Multi Conjugated Adaptive Optics (GMCAO) approach offers an alternative way to correct an adequate scientific Field of View (FoV) using only natural guide stars (NGSs) to extremely large ground-based telescopes. Thus, even in the absence of laser guide stars, a GMCAO-equipped ELT-like telescope can achieve optimal performance in terms of Strehl Ratio (SR), retrieving impressive results in studying star-poor fields, as in the cases of the deep field observations. The benefits and usability of GMCAO have been demonstrated by studying 6000 mock high redshift galaxies in the Chandra Deep Field South region. However, a systematic study simulating observations in several portions of the sky is mandatory to have a robust statistic of the GMCAO performance. Technical, tomographic and astrophysical parameters, discussed here, are given as inputs to GIUSTO, an IDL-based code that estimates the SR over the considered field, and the results are analyzed with statistical considerations. The best performance is obtained using stars that are relatively close to the Scientific FoV; therefore, the SR correlates with the mean off-axis position of NGSs, as expected, while their magnitude plays a secondary role. This study concludes that the SRs correlate linearly with the galactic latitude, as also expected. Because of the lack of natural guide stars needed for low-order aberration sensing, the GMCAO confirms as a promising technique to observe regions that can not be studied without the use of laser beacons. It represents a robust alternative way or a risk mitigation strategy for laser approaches on the ELTs.Comment: 18 pages, 10 figures, accepted for publication on PAS

Hierarchichal-segmented AO in order to attain wide field compensation in the visible on an 8m class telescope

We describe the preliminary optimized layout for a partially optimized concept of an optical-8m class VLT-like 2x2 segmented camera where each channel is assisted by an equivalent of an MCAO system where the ground layer correction is commonly employed while the high altitude ones is performed in an open-loop fashion. While we derive the basic relationships among the Field of View and attainable correction with a pre-defined choice for the hardware, we discuss sky coverage and wavefront sensing issues employing natural and artificial references, involving the latest stateof-the-art in the development of wavefront sensing. We show that a flexible approach allow for a compensated Field of View that is variable and can be properly tuned matching the current turbulence situation and the requirement in term of quality of the compensation. A preliminary description of the overall optomechanical package is given as well along with a rough estimates of the efforts required to translates such a concept into reality.Comment: 6 pages, 4 figures, in AO4ELT5 Proceeding

Multiple Spatial Frequencies Pyramid WaveFront Sensing

A modification of the pyramid wavefront sensor is described. In this conceptually new class of devices, the perturbations are split at the level of the focal plane depending upon their spatial frequencies, and then measured separately. The aim of this approach is to increase the accuracy in the determination of some range of spatial frequency perturbations, or a certain classes of modes, disentangling them from the noise associated to the Poissonian fluctuations of the light coming from the perturbations outside of the range of interest or from the background in the pupil planes; the latter case specifically when the pyramid wavefront sensor is used with a large modulation. While the limits and the effectiveness of this approach should be further investigated, a number of variations on the concept are shown, including a generalization of the spatial filtering in the point-diffraction wavefront sensor. The simplest application, a generalization to the pyramid of the well-known spatially filtering in wavefront sensing, is showing promise as a significant limiting magnitude advance. Applications are further speculated in the area of extreme adaptive optics and when serving spectroscopic instrumentation where “light in the bucket” rather than Strehl performance is required

Ingot Laser Guide Stars Wavefront Sensing

We revisit one class of z-invariant WaveFront sensor where the LGS is fired aside of the telescope aperture. In this way there is a spatial dependence on the focal plane with respect to the height where the resonant scattering occurs. We revise the basic parameters involving the geometry and we propose various merit functions to define how much improvement can be attained by a z-invariant approach. We show that refractive approaches are not viable and we discuss several solutions involving reflective ones in what has been nicknamed "ingot wavefront sensor" discussing the degrees of freedom required to keep tracking and the basic recipe for the optical design.Comment: 6 pages, 4 figures, AO4ELT5 Conference Proceeding, 201

Stampa di tavolette tattili per il Festival di Astronomia di Castellaro Lagusello

L’astronomia è uno dei campi del sapere che più affascina e attrae tutte le persone: chiunque può interrogarsi su come si è formato l’Universo, o cosa accadrà quando si spegnerà il Sole, o se esiste vita su altri pianeti. E tutti dovrebbero avere l’opportunità di conoscere le risposte a queste domande, almeno per quanto gli scienziati hanno scoperto finora. Per questa ragione l’Istituto Nazionale di Astrofisica sta perseguendo, da vari anni, strategie per rendere i suoi materiali didattici idonei anche a un pubblico di persone ipovedenti o non vedenti. Le risorse tipicamente disponibili per presentare concetti astronomici a persone con difficoltà visive sono limitate a figure tridimensionali, figure piane tattili e alcune lezioni in Braille. Alcune istituzioni accademiche, luoghi pubblici e musei hanno una selezione limitata di materiali adatti che possono essere utilizzati per elaborare concetti di astronomia e sono disponibili per l'uso da parte di visitatori e studenti ipovedenti. Imparare a presentare i concetti di astronomia secondo le esigenze individuali in questo modo non solo migliora l'apprezzamento individuale dei concetti e l'accesso alla conoscenza scientifica, ma promuove anche una cultura del rispetto per le differenze degli altri. Questo documento si pone come obiettivo quello di raccogliere e descrivere le prime esperienze di stampa 3D con la stampante Stratasys j55 volte e realizzare una serie di modelli tattili di galassie e costellazioni che saranno utilizzati durante la terza edizione del Festival di Astronomia di Castellaro Lagusello

A Holographic Diffuser Generalised Optical Differentiation Wavefront Sensor

The wavefront sensors used today at the biggest World's telescopes have either a high dynamic range or a high sensitivity, and they are subject to a linear trade off between these two parameters. A new class of wavefront sensors, the Generalised Optical Differentiation Wavefront Sensors, has been devised, in a way not to undergo this linear trade off and to decouple the dynamic range from the sensitivity. This new class of WFSs is based on the light filtering in the focal plane from a dedicated amplitude filter, which is a hybrid between a linear filter, whose physical dimension is related to the dynamic range, and a step in the amplitude, whose size is related to the sensitivity. We propose here a possible technical implementation of this kind of WFS, making use of a simple holographic diffuser to diffract part of the light in a ring shape around the pin of a pyramid wavefront sensor. In this way, the undiffracted light reaches the pin of the pyramid, contributing to the high sensitivity regime of the WFS, while the diffused light is giving a sort of static modulation of the pyramid, allowing to have some signal even in high turbulence conditions. The holographic diffuser zeroth order efficiency is strictly related to the sensitivity of the WFS, while the diffusing angle of the diffracted light gives the amount of modulation and thus the dynamic range. By properly choosing these two parameters it is possible to build a WFS with high sensitivity and high dynamic range in a static fashion. Introducing dynamic parts in the setup allows to have a set of different diffuser that can be alternated in front of the pyramid, if the change in the seeing conditions requires it.Comment: 11 pages, 5 figure

Il tour virtuale al Museo La Specola dell'Osservatorio Astronomico di Padova

Il rapporto descrive la procedura seguita per realizzare il tour virtuale del Museo 'La Specola', sezione museale dell’Osservatorio Astronomico di Padova: si tratta di un percorso museale accessibile a tutti tramite smartphone, tablet e pc. Esso si snoda attraverso sette diverse ‘stanze virtuali’, nelle quali si è accompagnati dalle voci-guida di Valeria Zanini e Federico Di Giacomo, che descrivono gli ambienti e gli strumenti utilizzati dagli astronomi padovani dei secoli passati. Grazie alle didascalie, si possono ottenere informazioni aggiuntive di approfondimento, mentre alcuni video e ricostruzioni 3D permettono di conoscere storie e aneddoti che fanno di questo luogo uno dei principali centri dell’astronomia italiana. Valeria Zanini, responsabile scientifica del patrimonio storico dell’Osservatorio, ha curato il percorso di visita; Federico Di Giacomo è il responsabile della progettazione e della realizzazione grafica del virtual tour; Marco Dima ha realizzato le immagini 360° e video 3D della linea meridiana

The Effect of Sports Activities on Motor and Social Skills in Autistic Children and Adolescents: a Systematic Narrative Review

BackgroundThe main traits of Autism Spectrum Disorder (ASD) are difficulties in social communication and interactions. Autism is frequently related to motor impairments. In the last decades, to develop and promote the social and motor skills of autistic people, several sports training programmes have been designed. In the present systematic narrative review, we aimed at providing an overview of studies evaluating the effectiveness of these sports training programmes to synthesize their strengths and weaknesses.MethodTo formulate the eligibility criteria for the systematic review, the PICO protocol was used. The PRISMA protocol was applied to four databases for the search strategy. 30 papers were reviewed, and their main features were tabulated and critically discussed.ResultsFindings highlighted that 8 types of sports were applied to autistic individuals and that the majority of them were focused on two individual sports (i.e., swimming and horseback riding). In sum, findings revealed that sports training programmes provided positive benefits both on motor/social skills as well as on autistic traits (e.g., repetitive behaviours) and individual functioning. The narrative synthesis revealed also that future studies should enroll more autistic females and preschoolers. To encourage the social inclusion of autistic individuals, a group of typically developing peers should be involved in future sports training programmes.DiscussionIn conclusion, professionals trained on autistic traits and knowledgeable in the target sport are required; consultations with the autistic community as guidance for designing novel sports training programmes are recommended

The effect of customer perceived value on customer satisfaction: a case study of Malay upscale restaurants

Stiff competition and increasingly high operating costs have driven many international and domestic players to introduce new outlet concepts. Malay fine dining, upscale restaurant segment is gaining popularity among Malaysian, especially in Kuala Lumpur. This study examined the effect of perceived value on customer satisfaction in Malay upscale restaurants in terms of emotional responses, monetary prices, behavioral price and reputation. Primary data were gathered from 170 questionnaires returned by respondents from five Malay upscale restaurants in Kuala Lumpur, and statistically analysed using SPSS version 21. The findings of this study revealed that monetary prices had a high positive relationship with customer satisfaction. In addition, the beta value for emotional responses (β=0.530, p<0.01), behavioral price (β=0.180, p<0.01) and reputation (β=0.168, p<0.01) also indicated the respective contributions made to customer satisfaction