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32 results on '"Sivo, G."'

1. Strategic Scientific Plan for Gemini Observatory

Author

Blakeslee, J. P., Adamson, A., Davis, C., Díaz, R., Miller, B., Peck, A., Rutten, R., Sivo, G., Thomas-Osip, J., Boroson, T., Carrasco, R., Dennihy, E., Díaz, M., Ferrarese, L., Green, R., Hirst, P., Hwang, N., Jørgensen, I., Kim, H., Kleinman, S., Labrie, K., Lee, T., Lotz, J., Leggett, S., Medina, L., Nitta, A., Pollard, J., Roe, H., Rantakyro, F., Rudnick, G., Salinas, R., Sawicki, M., and Van Der Hoeven, M.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We present the Strategic Scientific Plan (SSP) for the direction and activities of the Gemini Observatory in the 2020s. The overarching goal is to ensure that Gemini best uses the available resources to serve the needs of its international user community throughout the coming decade. The actionable items fall into three general categories: (1) preserving Gemini's current facilities and strengths; (2) developing instrumentation and software systems, including data pipelines, to enable new scientific capabilities that build on those strengths; (3) strategizing how visiting instruments can deliver additional valuable capabilities. We provide a high-level timeline (schematically illustrated in one figure) for the main developments discussed in this SSP. The schedule is ambitious, but in light of the recent Gemini in the Era of Multi-Messenger Astronomy (GEMMA) award from the NSF, the plan becomes achievable. Lists of milestones are given for gauging progress. As these milestones are reached and new instruments become available, some current instruments will need to be retired; we make recommendations in this regard. The final section concludes by reemphasizing the importance of a strong partnership committed to the needs of all members., Comment: Basic version with minimal illustration, 30 pages with 4 figures. For richly illustrated versions with the same textual content, see: http://www.gemini.edu/news/gemini-strategic-scientific-plan

Published
2019

2. Probing the Time Domain with High Spatial Resolution

Author

Blakeslee, J. P., Rodney, S. A., Lotz, J. M., Sivo, G., Sivanandam, S., Andersen, M., Carrasco, R., Ferrarese, L., Foley, R. J., Goodsell, S., Hirst, P., Jensen, J. B., Kelly, P. L., Kaurov, A. A., Lemoine-Busserolle, M., Miller, B. W., O'Meara, J., Roe, H., Schwamb, M. E., and Scharwächter, J.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Two groundbreaking new facilities will commence operations early in the 2020s and thereafter define much of the broad landscape of US optical-infrared astronomy in the remaining decade. The Large Synoptic Survey Telescope (LSST), perched atop Cerro Pachon in the Chilean Andes, will revolutionize the young field of Time Domain Astronomy through its wide-field, multi-band optical imaging survey. At the same time, the James Webb Space Telescope (JWST), orbiting at the Sun-Earth L2 Lagrange point, will provide stunningly high-resolution views of selected targets from the red end of the optical spectrum to the mid-infrared. However, the spatial resolution of the LSST observations will be limited by atmospheric seeing, while JWST will be limited in its time-domain capabilities. This paper highlights the scientific opportunities lying between these two landmark missions, i.e., science enabled by systems capable of astronomical observations with both high cadence in the time domain and high resolution in the spatial domain. The opportunities range from constraining the late phases of stellar evolution in nearby resolved populations to constraining dark matter distributions and cosmology using lensed transient sources. We describe a system that can deliver the required capabilities., Comment: Science white paper submitted to Astro2020

Published
2019

3. Towards an automatic wind speed and direction profiler for Wide Field AO systems

Author

Sivo, G., Turchi, A., Masciadri, E., Guesalga, A., and Neichel, B.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Atmospheric and Oceanic Physics
Abstract

Wide Field Adaptive Optics (WFAO) systems are among the most sophisticated AO systems available today on large telescopes. The knowledge of the vertical spatio-temporal distribution of the wind speed (WS) and direction (WD) are fundamental to optimize the performance of such systems. Previous studies already proved that the Gemini Multi-Conjugated AO system (GeMS) is able to retrieve measurements of the WS and WD stratification using the SLODAR technique and to store measurements in the telemetry data. In order to assess the reliability of these estimates and of the SLODAR technique applied to such a kind of complex AO systems, in this study we compared WS and WD retrieved from GeMS with those obtained with the atmospherical model Meso-Nh on a rich statistical sample of nights. It has been previously proved that, the latter technique, provided an excellent agreement with a large sample of radiosoundings both, in statistical terms and on individual flights. It can be considered, therefore, as an independent reference. The excellent agreement between GeMS measurements and the model that we find in this study, proves the robustness of the SLODAR approach. To by-pass the complex procedures necessary to achieve automatic measurements of the wind with GeMS, we propose a simple automatic method to monitor nightly WS and WD using the Meso-Nh model estimates. Such a method can be applied to whatever present or new generation facilities supported by WFAO systems. The interest of this study is, therefore, well beyond the optimization of GeMS performance., Comment: 9 figures, 2 tables, MNRAS accepted

Published
2018
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4. Experience with wavefront sensor and deformable mirror interfaces for wide-field adaptive optics systems

Author

Basden, A. G., Atkinson, D., Bharmal, N. A., Bitenc, U., Brangier, M., Buey, T., Butterley, T., Cano, D., Chemla, F., Clark, P., Cohen, M., Conan, J. -M., de Cos, F. J., Dickson, C., Dipper, N. A., Dunlop, C. N., Feautrier, P., Fusco, T., Gach, J. L., Gendron, E., Geng, D., Goodsell, S. J., Gratadour, D., Greenaway, A. H., Guesalaga, A., Guzman, C. D., Henry, D., Holck, D., Hubert, Z., Huet, J. M., Kellerer, A., Kulcsar, C., Laporte, P., Roux, B. Le, Looker, N., Longmore, A. J., Marteaud, M., Martin, O., Meimon, S., Morel, C., Morris, T. J., Myers, R. M., Osborn, J., Perret, D., Petit, C., Raynaud, H., Reeves, A. P., Rousset, G., Lasheras, F. Sanchez, Rodriguez, M. Sanchez, Santos, J. D., Sevin, A., Sivo, G., Stadler, E., Stobie, B., Talbot, G., Todd, S., Vidal, F., and Younger, E. J.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract

Recent advances in adaptive optics (AO) have led to the implementation of wide field-of-view AO systems. A number of wide-field AO systems are also planned for the forthcoming Extremely Large Telescopes. Such systems have multiple wavefront sensors of different types, and usually multiple deformable mirrors (DMs). Here, we report on our experience integrating cameras and DMs with the real-time control systems of two wide-field AO systems. These are CANARY, which has been operating on-sky since 2010, and DRAGON, which is a laboratory adaptive optics real-time demonstrator instrument. We detail the issues and difficulties that arose, along with the solutions we developed. We also provide recommendations for consideration when developing future wide-field AO systems., Comment: Accepted for publication in MNRAS

Published
2016
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9. Experience with wavefront sensor and deformable mirror interfaces for wide-field adaptive optics systems

Author

Basden, A. G., primary, Atkinson, D., additional, Bharmal, N. A., additional, Bitenc, U., additional, Brangier, M., additional, Buey, T., additional, Butterley, T., additional, Cano, D., additional, Chemla, F., additional, Clark, P., additional, Cohen, M., additional, Conan, J.-M., additional, de Cos, F. J., additional, Dickson, C., additional, Dipper, N. A., additional, Dunlop, C. N., additional, Feautrier, P., additional, Fusco, T., additional, Gach, J. L., additional, Gendron, E., additional, Geng, D., additional, Goodsell, S. J., additional, Gratadour, D., additional, Greenaway, A. H., additional, Guesalaga, A., additional, Guzman, C. D., additional, Henry, D., additional, Holck, D., additional, Hubert, Z., additional, Huet, J. M., additional, Kellerer, A., additional, Kulcsar, C., additional, Laporte, P., additional, Le Roux, B., additional, Looker, N., additional, Longmore, A. J., additional, Marteaud, M., additional, Martin, O., additional, Meimon, S., additional, Morel, C., additional, Morris, T. J., additional, Myers, R. M., additional, Osborn, J., additional, Perret, D., additional, Petit, C., additional, Raynaud, H., additional, Reeves, A. P., additional, Rousset, G., additional, Sanchez Lasheras, F., additional, Sanchez Rodriguez, M., additional, Santos, J. D., additional, Sevin, A., additional, Sivo, G., additional, Stadler, E., additional, Stobie, B., additional, Talbot, G., additional, Todd, S., additional, Vidal, F., additional, and Younger, E. J., additional

Published
2016
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10. Validation ciel d'une commande haute performance en optique adaptative classique et multi-objet sur le démonstrateur CANARY

Author

Sivo, G., ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Laboratoire Charles Fabry / Spim, Laboratoire Charles Fabry (LCF), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut d'Optique Graduate School (IOGS), Université Paris 13, and Caroline Kulcsar

Subjects
ADAPTIVE OPTICS, VIBRATION FILTERING, MULTI-OBJECT ADAPTIVE OPTICS, FILTRAGE VIBRATION, OPTIQUE ADAPTATIVE, LQG CONTROL, COMMANDE LQG, [SPI.AUTO]Engineering Sciences [physics]/Automatic, OBSERVATION ASTRONOMIQUE, FILTRE KALMAN, COMMANDE VARIANCE MINIMALE, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, REPRESENTATION ETAT, ASTRONOMICAL OBSERVATIONS, KALMAN FILTER, MINIMUM VARIANCE CONTROL, STATE SPACE REPRESENTATION, OPTIQUE ADAPTATIVE MULTI-OBJET
Abstract

Adaptive Optics (AO), which enables to correct in real time wavefront deformation induced by atmospheric turbulence, faces a fundamental limitation: anisoplanatism. To counter it, the concept of Wide-Field AO (WFAO) has been proposed. Turbulence is measured in several directions of the field of view, using natural and laser guide stars, and its impact on images is mitigated by a control based on tomographic reconstruction. The Linear Quadratic Gaussian (LQG) approach is well-suited to AO control design in both WFAO and classical AO. LQG enables to estimate and predict the phase with a Kalman filter based on spatial and temporal priors. State-space models and associated controls are laid out. The first on-sky implementation of LQG control on all modes, in classical and multi-object AO, is presented on the CANARY pathfinder. These results have been obtained with identification of tip-tilt models and vibration filtering, which constitutes the first on-sky implementation of this strategy. Spatial priors on the phase in the volume are identified using the LEARN algorithm. Data from the stereoSCIDAR profilometer were also used. Comparisons are provided with integral AO control in standard AO, showing significant gain in performance with LQG. Comparisons with the static reconstructor APPLY (regularized least-squares) in multi-object AO show a gain in performance with LQG in some cases (especially in high-noise conditions). Results confirm feasibility and relevance of LQG control for AO or WFAO instruments.; L'optique adaptative (OA), qui permet de corriger en temps-réel les déformations du front d'onde induites par la turbulence atmosphérique, connaît une limitation fondamentale : l'anisoplanétisme. Pour y remédier, le concept d'OA grand champ (OAGC) a été proposé. La turbulence est mesurée dans plusieurs directions du champ de vue à l'aide d'étoiles guide naturelles et laser, et son impact corrigé sur les images par une commande basée sur une reconstruction tomographique. L'approche linéaire quadratique gaussienne (LQG) est bien adaptée à la conception de lois de commande en OAGC comme en OA classique. Elle permet d'estimer et de prédire la phase à l'aide d'un filtre de Kalman basé sur des a priori spatiaux et temporels. Les modèles d'état et commandes associées sont détaillés. On présente la première mise en œuvre sur le ciel d'une commande LQG sur tous les modes, en OA classique et multi-objet, à l'aide du démonstrateur CANARY. Ces résultats sont obtenus avec identification du modèle de tip-tilt et filtrage des vibrations, ce qui constitue la première mise en œuvre ciel de cette stratégie. Les a priori spatiaux de la phase en volume sont identifiés par la méthode LEARN. Des données issues du profilomètre stereoSCIDAR ont aussi été utilisées. Des comparaisons sont proposées avec une commande intégrateur en OA classique, avec un gain significatif en performances pour le LQG. Les comparaisons avec le reconstructeur statique APPLY (moindres carrés régularisés) en OA multi-objet mettent en évidence un gain du LQG dans certains cas (fort bruit en particulier). L'ensemble des résultats confirme la faisabilité et l'intérêt d'une commande LQG pour un instrument d'OA ou d'OAGC.

Published
2013

11. On-sky validation of high performance control in classical and multi-object adaptive optics on CANARY pathfinder

Author

Sivo, G., ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Laboratoire Charles Fabry / Spim, Laboratoire Charles Fabry (LCF), Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), Université Paris 13, and Caroline Kulcsar

Subjects
ADAPTIVE OPTICS, VIBRATION FILTERING, MULTI-OBJECT ADAPTIVE OPTICS, FILTRAGE VIBRATION, OPTIQUE ADAPTATIVE, LQG CONTROL, COMMANDE LQG, [SPI.AUTO]Engineering Sciences [physics]/Automatic, OBSERVATION ASTRONOMIQUE, FILTRE KALMAN, COMMANDE VARIANCE MINIMALE, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, REPRESENTATION ETAT, ASTRONOMICAL OBSERVATIONS, KALMAN FILTER, MINIMUM VARIANCE CONTROL, STATE SPACE REPRESENTATION, OPTIQUE ADAPTATIVE MULTI-OBJET
Abstract

Adaptive Optics (AO), which enables to correct in real time wavefront deformation induced by atmospheric turbulence, faces a fundamental limitation: anisoplanatism. To counter it, the concept of Wide-Field AO (WFAO) has been proposed. Turbulence is measured in several directions of the field of view, using natural and laser guide stars, and its impact on images is mitigated by a control based on tomographic reconstruction. The Linear Quadratic Gaussian (LQG) approach is well-suited to AO control design in both WFAO and classical AO. LQG enables to estimate and predict the phase with a Kalman filter based on spatial and temporal priors. State-space models and associated controls are laid out. The first on-sky implementation of LQG control on all modes, in classical and multi-object AO, is presented on the CANARY pathfinder. These results have been obtained with identification of tip-tilt models and vibration filtering, which constitutes the first on-sky implementation of this strategy. Spatial priors on the phase in the volume are identified using the LEARN algorithm. Data from the stereoSCIDAR profilometer were also used. Comparisons are provided with integral AO control in standard AO, showing significant gain in performance with LQG. Comparisons with the static reconstructor APPLY (regularized least-squares) in multi-object AO show a gain in performance with LQG in some cases (especially in high-noise conditions). Results confirm feasibility and relevance of LQG control for AO or WFAO instruments.; L'optique adaptative (OA), qui permet de corriger en temps-réel les déformations du front d'onde induites par la turbulence atmosphérique, connaît une limitation fondamentale : l'anisoplanétisme. Pour y remédier, le concept d'OA grand champ (OAGC) a été proposé. La turbulence est mesurée dans plusieurs directions du champ de vue à l'aide d'étoiles guide naturelles et laser, et son impact corrigé sur les images par une commande basée sur une reconstruction tomographique. L'approche linéaire quadratique gaussienne (LQG) est bien adaptée à la conception de lois de commande en OAGC comme en OA classique. Elle permet d'estimer et de prédire la phase à l'aide d'un filtre de Kalman basé sur des a priori spatiaux et temporels. Les modèles d'état et commandes associées sont détaillés. On présente la première mise en œuvre sur le ciel d'une commande LQG sur tous les modes, en OA classique et multi-objet, à l'aide du démonstrateur CANARY. Ces résultats sont obtenus avec identification du modèle de tip-tilt et filtrage des vibrations, ce qui constitue la première mise en œuvre ciel de cette stratégie. Les a priori spatiaux de la phase en volume sont identifiés par la méthode LEARN. Des données issues du profilomètre stereoSCIDAR ont aussi été utilisées. Des comparaisons sont proposées avec une commande intégrateur en OA classique, avec un gain significatif en performances pour le LQG. Les comparaisons avec le reconstructeur statique APPLY (moindres carrés régularisés) en OA multi-objet mettent en évidence un gain du LQG dans certains cas (fort bruit en particulier). L'ensemble des résultats confirme la faisabilité et l'intérêt d'une commande LQG pour un instrument d'OA ou d'OAGC.

Published
2013

12. Towards an automatic wind speed and direction profiler forWide Field adaptive optics systems.

Author

Sivo, G., Turchi, A., Masciadri, E., Guesalaga, A., and Neichel, B.

Subjects
WIND speed, ADAPTIVE optics, TELEMETRY, STAR observations, STAR formation
Abstract

Wide Field Adaptive Optics (WFAO) systems are among the most sophisticated adaptive optics (AO) systems available today on large telescopes. Knowledge of the vertical spatio-temporal distribution of wind speed (WS) and direction (WD) is fundamental to optimize the performance of such systems. Previous studies already proved that the Gemini Multi-Conjugated AO system (GeMS) is able to retrieve measurements of the WS and WD stratification using the SLOpe Detection And Ranging (SLODAR) technique and to store measurements in the telemetry data. In order to assess the reliability of these estimates and of the SLODAR technique applied to such complex AO systems, in this study we compared WS and WD values retrieved from GeMS with those obtained with the atmospheric model Meso-NH on a rich statistical sample of nights. It has previously been proved that the latter technique provided excellent agreement with a large sample of radiosoundings, both in statistical terms and on individual flights. It can be considered, therefore, as an independent reference. The excellent agreement between GeMS measurements and the model that we find in this study proves the robustness of the SLODAR approach. To bypass the complex procedures necessary to achieve automatic measurements of the wind with GeMS, we propose a simple automatic method to monitor nightly WS and WD using Meso-NH model estimates. Such a method can be applied to whatever present or new-generation facilities are supported byWFAO systems. The interest of this study is, therefore, well beyond the optimization of GeMS performance. [ABSTRACT FROM AUTHOR]

Published
2018
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13. A new slow focus sensor for GeMS

Author

Marin, E., Garrel, V., Sivo, G., Montes, V., Trujillo, C., Rambold, W., Gigoux, P., Moreno, C., Galvez, R., Gausachs, G., Barreau, Matthieu, Marin, E., Garrel, V., Sivo, G., Montes, V., Trujillo, C., Rambold, W., Gigoux, P., Moreno, C., Galvez, R., Gausachs, G., and Barreau, Matthieu

Abstract

The Gemini South 8-meter telescope's Multi Conjugate Adaptive Optics System GeMS is about to enter a new era of science with an entire new upgrade for its Natural Guide Star wave front sensor (NGS2). With NGS2 the limiting magnitude of the natural guide stars used for tip/tilt sensing is expected to increase from its current limit of 15.4 to 17+ in R-band. This will provide a much greater sky coverage over the current system. NGS2 is a complete replacement of the current Natural Guide Star wave front sensor (NGS). This presents an interesting challenge as the current NGS includes a Slow Focus Sensor (SFS) used to compensate for the sodium layer mean altitude variations. With the new NGS2 setup, this SFS will be removed and a suitable replacement must be found. Within the Gemini environment there exist two facility wave front sensors, Peripheral Wave Front Sensors one and two (PWFS1 and PWFS2), that could act as an SFS. Only one of these (PWFS1) is located optically in front of the GeMS Adaptive Optics (AO) bench (Canopus). We are currently preparing this wave front sensor as the new SFS for GeMS under the NGS2 setup. The results of several nighttime and daytime tests show that PWFS1 will be an adequate SFS for GeMS in the NGS2 setup providing excellent sky coverage without compromising the GeMS Field of View (FoV)., QC 20170307

Published
2015
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31. Redazione di 17 schede in Repertorio di esempi di intervento in 'Il recupero delle coperture' di B. de Sivo ed altri

Author

AUSIELLO, GIGLIOLA, A. Napoletano, F. Ribera, M. L. Sabatini, B. de Sivo G. Cito, G. Giordano, R. Iovino, Ausiello, Gigliola, A., Napoletano, F., Ribera, and M. L., Sabatini

Subjects
interventi di recupero delle coperture
Abstract

Il contributo si esplicita in 17 schede tecniche su interventi di recupero delle coperture nel volume "Il recupero delle coperture" di B. de Sivo G. Cito, G. Giordano, R. Iovino, per i tipi di Dario Flaccovio Editore.

Published
1992

32. First on-sky SCAO validation of full LQG control with vibration mitigation on the CANARY pathfinder.

Author

Sivo G, Kulcsár C, Conan JM, Raynaud HF, Gendron E, Basden A, Vidal F, Morris T, Meimon S, Petit C, Gratadour D, Martin O, Hubert Z, Sevin A, Perret D, Chemla F, Rousset G, Dipper N, Talbot G, Younger E, Myers R, Henry D, Todd S, Atkinson D, Dickson C, and Longmore A

Subjects
Equipment Design, Astronomy instrumentation, Computer Simulation, Lenses, Models, Theoretical, Optics and Photonics instrumentation, Telescopes
Abstract

Adaptive optics provides real time correction of wavefront disturbances on ground based telescopes. Optimizing control and performance is a key issue for ever more demanding instruments on ever larger telescopes affected not only by atmospheric turbulence, but also by vibrations, windshake and tracking errors. Linear Quadratic Gaussian control achieves optimal correction when provided with a temporal model of the disturbance. We present in this paper the first on-sky results of a Kalman filter based LQG control with vibration mitigation on the CANARY instrument at the Nasmyth platform of the 4.2-m William Herschel Telescope. The results demonstrate a clear improvement of performance for full LQG compared with standard integrator control, and assess the additional improvement brought by vibration filtering with a tip-tilt model identified from on-sky data, thus validating the strategy retained on the instrument SPHERE at the VLT.

Published
2014
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