The DAG (Dogu Anadolu Gözlemevi) observatory is the largest observatory in Turkey and is composed by the 4m-class infrared Telescope, the Rotating Enclosure, the dome fixed structure and the auxiliary building. It is mounted on the top of Karakaya Mountain at 3170m altitude, close to Erzurum, in Turkey. This presentation refers to the DAG Rotating Enclosure. The Rotating Enclosure is octagonal sized steel structure with eight trolleys acting on a rai of 18.6 meters diameter. The structure is and 14.5m high over a pillar 9.0m. It is equipped with an observing slit door composed by two L-Shaped elements. Six sliding ventilation doors, about 3.7x6.5m each, that can be opened independently and with different degrees of aperture allow for optimizing the internal airflow. Immediately Inside the observing slit doors, there is a windscreen consisting of 3 panels that, in case of wind, are raised in accordance with the telescope elevation to protect it. The panels have a specific degree of air permeability to still allow ventilation for the telescope. A 6.5tons overall bridge crane allows to move pieces in every zone of the rotating enclosure for the maintenance of the telescope optics. At the beginning of November 2023, EIE carried out all acceptance tests with the end customer and delivered the rotating enclosure to ATASAM. This paper provides the results of the final erection and reports the procedures and results of the Acceptance Tests performed by EIE for the DAG Rotating Enclosure activities. 4m class telescopes and related Domes represent nowadays a consolidated part of EIE core-business, a low costs standard product able to satisfy the most critical observational requirements of astronomers.
The Multiplexed Survey Telescope (MUST) is 6.5m class optical telescope to be located in China, at Saishiteng Mountain, Lenghu Town, Qinghai Province. The elevation is approximately 4.350m above sea level. The telescope consists of an Alt-Azimuth telescope housed in an enclosure, called “Dome” constituted by a base and a rotating part. The MUST Rotating Enclosure will provide environmental protection and control to the Telescope during operation and standby conditions as well as providing the infrastructure required for the operation of the Telescope. The Auxiliary Building will house plant, maintenance and storage facilities. The Auxiliary Building will also include the necessary housing for the installation of the coating facility for the primary and secondary mirrors. The Dome must operate continuously without rotational travel limits to accommodate the Telescope cadence and travel, so this prevents the use of a utility cable wrap. Moreover, in order to minimize the power transferred to the rotating part, the azimuth drives are located in the fixed lower enclosure. A non-corotating dome architecture is chosen in order to improve flexibility during telescope maintenance and material handling. The rotating enclosure dome includes a moving wind screen, ventilation doors and a rear access door for main mirror handling. An air duct system aligns when the Dome is in its parked position and provides air cooling for temperature conditioning of the Dome during the daytime. A bridge crane and a series of ladders, stairs and platforms provide for the inspection, maintenance and repair of all of the Dome mechanical systems. The contract to design and build the rotating dome and design the lower enclosure and auxiliary building was awarded to EIE GROUP in Mestre- Venezia, Italy in 22/12/22. In this paper, we present the preliminary design of the dome and auxiliary building facility and their sub-systems.
Rubin Observatory Dome was designed and built by EIE GROUP with headquarters in Venice-Mestre, Italy. The Design Phase was completed in February 2016. On-site activities started in the spring of 2017. The Dome is approaching the final completion of testing and integration. The Dome utilizes a steel structure. This supports a bi-parting, two door aperture, a uniquely designed moving Light Windscreen, a Light Baffled Louver System, an overhead bridge crane, a rear access door and numerous platforms. In this paper, we present the status of the final assembly, integration and testing.
The DAG (Dogu Anadolu Gözlemevi) Eastern Anatolia Observatory is an astronomical project fully funded by Turkish Ministry of Development and the Atatürk University of Astrophysics Research Telescope (ATASAM). DAG Observatory is provided with a 4m-class optical and infrared telescope, equipped with secondary (0.76m) and tertiary mirrors which furnish the telescope with two Nasmyth foci. Since 2015, the project has seen the crucial contribution of EIE GROUP in the Design, Production and on-site Installation of the mount structure of the 4m class optical/nearinfrared telescope (DAG Telescope) in contract with AMOS company. EIE GROUP is also the main contractor of the 18.6m-diameter Rotating Building (DAG Dome) at an altitude of 3170m asl on the Erzurum Plateau, Turkey. After completing a full assembly and testing in the factory, the telescope was subsequently disassembled and transported to the final installation site. Now, on-site assembly activities have been completed, and all internal acceptance tests regarding the mount structure have been conducted. This document focuses on the on-site assembly activities of the EIE Group, as well as the related internal pre-commissioning, commissioning, and functional and acceptance tests.
The identification, classification, and monitoring of Near-Earth Objects (NEO) is of detrimental importance for the implementation of the Space Safety Program (S2P) supported by the European Space Agency. The Near-Earth Object Survey TELescope (NEOSTEL, also known as “Flyeye”), represents a key-element of S2P: its role consists in providing a real-time monitoring system from ground of potential impactors, generating an early-warning signal with a maximum delay of three days from detection to the alert generation. As a by-product, the system is capable of detecting, classifying and monitoring space debris, contributing to the implementation of strategies for collision avoidance. Due to the peculiarities of the “Flyeye” telescope, and in virtue of the service availability that must be guaranteed to perform the required observational schedule, the hosting astronomical observatory shall comply to specific and tight requirements. On the observatory side, the telescope combines the observational capability of sixteen cameras, capable of generating the map of the entire accessible sky four times per observing night. Data must then be stored, pre-processed and made available for the generation of the alerts. The rotating dome is also subject to strict requirements, since the combination of fast telescope slewing and equatorial mount configuration makes the requests to the enclosure rotational velocity extremely demanding. Furthermore, the system shall be deployed into much different sites, to guarantee 24/7 global service availability, making compliance to the varying environmental conditions extremely impacting on the design. In this paper we present the results of the optimized layout of the observatory, with a description of the main technical tradeoff.
COSMO Large Coronagraph (COSMO LC) is a telescope dedicated to the measurement of the Sun magnetic field. This project is currently at a design phase funded by the National Science Foundation under the technical direction of the High Altitude Observatory.
COSMO LC is a refractive telescope whose objective lens has a clear aperture of 1.4m, it will be the largest refractive telescope in the world. This telescope can observe the Sun corona thanks to the internal occulter which is able to obscure the solar disk. This device needs to accomplish two main functions: 1) adapt its diameter to the Sun apparent size, 2) reject all the incoming heat to not start any air turbulence which leads to the degradation of image quality (seeing).
Diameter change is accomplished by means of a cam mechanism which actuates 14 petals arranged azimuthally while the occulter cooling is obtained through cold water running through internal channels and forced air convection.
This article describes the mathematical models employed to quantify the seeing effect on image resolution and the technical solutions adopted to implement the above-mentioned functions. In addition, the tests performed on this device are described along with the results.
The ground calibration of the NewATHENA mirror poses significant challenges owing to its unprecedented size, mass, and focal length. VERT-X is an innovative calibration facility designed to tackle this exceptionally demanding task. It relies on an X-ray parallel beam, generated by a micro-focus source positioned at the focus of an X-ray collimator. A raster-scan mechanism enables the beam movement, covering all NewATHENA optics at varying off-axis angles. The compactness of the concept offers several benefits, including the vertical geometry which implies minimal PSF degradation due to lateral gravity. Furthermore, this allows for a flexible choice of location. Indeed one of the most important feature of VERT-X is its contiguity with the mirror integration facility. The driving factor in the VERT-X design is to meet the NewATHENA calibration requirement for Half- Energy Width (HEW) accuracy at 0.1”. Key contributors to the error budget in the VERT-X design include the source size, collimator error, and raster-scan pointing accuracy. This paper provides an overview of the current status of the development of these critical parts.
With the endorsement of the NewAthena (New Advanced Telescope for High ENergy Astrophysics) mission by ESA’s Science Programme Committee in November 2023, the preparations for this next generation X-ray observatory have shifted to a higher gear. Competitive system studies and technology preparation activities are being implemented, aiming to demonstrate readiness for the mission adoption early 2027 and the subsequent mission implementation.
The Silicon Pore Optics (SPO) enables the NewAthena mission, delivering an unprecedented combination of good angular resolution, large effective area and low mass. The SPO technology builds significantly on spin-in from the semiconductor industry and is designed to allow a cost-effective flight optics implementation, compliant with the programmatic requirements of the mission.
The NewAthena X-ray optics is highly modular, consisting of hundreds of compact mirror modules arranged in concentric circles and mounted on a metallic optical bench. All aspects of the optics are being developed in parallel, from the industrial production of the mirror plates, over the highly efficient assembly into mirror modules, to the alignment of the mirror modules and their fixation on the optical bench. Dedicated facilities are being built to measure the performance of the NewAthena X-ray telescope optics, demonstrating their compatibility with the environmental and scientific requirements.
An overview is provided of the activities preparing the implementation of the NewATHENA optics.
The Dogu Anadolu Gözlemevi (DAG) Eastern Anatolia Observatory is an astronomical project fully funded by Turkish Ministry of Development and the Atatürk University of Astrophysics Research Telescope (ATASAM). DAG Observatory will be provided with a 4m-class optical and infrared telescope, equipped with secondary (0.76m) and tertiary mirrors which furnish the telescope with two Nasmyth foci. Since 2015, the project has seen the crucial contribution of EIE GROUP in the Design, Production and on-site Installation of the 4m class optical/near-infrared telescope (DAG Telescope) in contract with AMOS company. EIE GROUP is also the main contractor of the 18.6m-diameter Rotating Building (DAG Dome) at an altitude of 3170m asl on the Erzurum Plateau, Turkey. The telescope was completely pre-assembled and successfully tested at the Integration Area Facilities of the EIE GROUP. Subsequently disassembled and transported to the final installation site. Despite the serious effects of the pandemic, the EIE GROUP, in agreement with its final Customer, has adopted a telescope assembly strategy integrated with the final assembly phases of the Dome. This allowed EIE to mount the entire telescope, in a single summer season, in total safety (thanks to the special measures adopted). This paper focuses on the development of this on-site assembly EIE activities of DAG Telescope, which at present have exceeded the 95% of completion. The main critical issues and related engineering solutions will be analyzed, with emphasis on both managerial and erection approaches adopted by EIE GROUP for this integrated phase of the project completion.
Proper thermal behavior of a telescope mainly means three things: 1) avoid thermal-induced deflections, 2) avoid high solid-to-air temperature differences that cause seeing, and 3) maintain the temperature of the electronics and of the optical instruments within their operative range. To evaluate the ability of the telescope to fulfil the thermal aims in the design phase, at least two types of thermal models are used: finite element models, and dynamic block models. EIE developed a complete procedure to integrate the two types of thermal models, based on the concept of thermal modal analysis.
The Vera C. Rubin Observatory is the result of a public-private partnership between the USA National Science Foundation (NSF), the lead Federal Agency of the project, the Department of Energy and the Association Of Universities For Research In Astronomy (AURA), and the LSST Corporation. EIE GROUP has developed the Detail Design, the Manufacturing, and the Erection on Site of the giant Rotating Building. In this regard, 2021 was a year full of successes for the development of the project.
High vibrations levels are detrimental to telescope pointing performance. Unfortunately, the true (final) vibration level on the telescope structure can be measured only when the machine is commissioned, i.e. much after the design phase is over. In this context, to reduce engineering risk, it can be useful to assess telescope vibrations very early - also in the preliminary design phase - in order, if needed, to adopt suitable countermeasures (e.g.: vibration damping, structure stiffening, or vibration isolation). This is particularly important in giant telescopes, since their natural frequencies are typically low enough to fall next to many vibration sources (wind, pumps, bogies, electric fans, vortex shedding). EIE developed an integrated procedure to assess the vibration level at the telescope hosted units - mirrors and instruments. The procedure: (i) identifies the relevant vibration sources, (ii) evaluates the vibration level for each source at the generation point, (iii) transfers the vibration from the generation point to the hosted units, and (iv) combines statistically the vibration sources to get the final vibration level. This paper presents EIE integrated procedure for the vibration assessment, and it discusses the most relevant vibration sources to be taken into account in giant telescopes.
Calibration of the ATHENA telescope is a critical aspect of the project and raises significant difficulties due to the unprecedented size, mass and focal length of the mirror assembly. The VERT-X project, financed by ESA and started in January 2019 by a Consortium led by INAF and which includes EIE, Media Lario Technologies, GPAP, and BCV Progetti, aims to design an innovative calibration facility. In the VERT-X design the parallel beam, needed for calibration, is produced placing a source in the focus of an X-ray collimator. This system is mounted on a raster-scan mechanism which covers the entire ATHENA optics. The compactness of the VERT-X design allows a vertical geometry for the ATHENA calibration facility, with several potential benefits with respect to the long horizontal tube calibration facilities.
The ATHENA X-ray observatory is a large-class ESA approved mission, with launch scheduled in 2028. The technology of Silicon Pore Optics (SPO) was selected since 2004 as the baseline for making the X-ray Mirror Assembly. Up to 700 mirror modules to obtain a nested Wolter like optics. The maximum diameter of the shells will be 2.5 m while the focal length is 12 m. The requirements for on-axis angular resolution and effective area at 1 keV are 5 arcsec HEW and 1.4 m2, while the field of view will be 40 arcmin in diameter (50 % vignetting). While in this moment there an on-going effort aiming at demonstrating the feasibility of a so large optics with so stringent scientific requirements, an important aspect to be considered regards the scientific calibrations of the X-ray optics. In this respect, the Point Spread Function and effective area have to be correctly measured and calibrated on-ground at different energies across the entire field of view, with a low vignetting. The approach considered so far foresees the use of a long (several hundreds of meters) facility to allow a full illumination with low divergence of the entire optics module (or at least of large sections of it). The implementation of similar configurations in a completely new facility to be realized in Europe (friendly called "super Panter") or the retrofitting existing facilities like the XRCF at NASA/MSFC are being considered. In both cases the costs and the programmatic risks related to the implementation of these huge facilities, with their special jigs for the alignment of the ATHENA optics, represent important aspects to be considered. Moreover, the horizontal position of the optics to be used in full illumination facilities would determine gravitational deformations, not easy to be removed with actuators or by modeling. In this talk we will discuss a completely different concept, based on the mount of the optics in vertical position and the use of a raster scan of the ATHENA optics with a small (a few cm2 wide) highly collimated (1 arcsec or so) white beam X-ray. This system will allow us to operate a much compact system. The use of a vertical configuration will imply smaller gravitational deformations, that can be controlled with actuators able to compensate them. A proper camera system with a sufficient energy resolution will be able to grant a correct measurement of both PSF and effective area of the Mirror Assembly within the calibration requirements and in a reasonable integration time. Moreover, it may allow us also to perform end-to-end tests using the two flight focal plane instruments of ATHENA. The cost and risks for the implementation would be much lower than for the full illumination systems. The conceptual configuration and preliminary expected performance of the facility will be discussed.
The European Extremely Large Telescope (E-ELT), with its primary mirror diameter of 39 meters, will be the largest optical/near-infrared telescope in the world and will allow scientists to investigate important unsolved issues of the universe.
The dome and telescope (DMS) are designed to ensure high performance in one of the most seismic active areas in the world, Cerro Armazones in Chile.
The Dome diameter is 86 m and sits on the top of a stiff concrete pier, which has been designed with horizontal seismic devices to reduce the seismic accelerations on the structures. The isolation system consists of a combination of High Damping Rubber Bearings (HDRBs) and lubricated spherical bearings.
The Telescope structure has been designed to be adaptive, during operation it is extremely stiff with low damping to guarantee the pointing and tracking (fixed condition) and when subjected to strong earthquakes it is flexible with high damping (isolated condition) to reduce the accelerations on the mirrors and instruments.
To fulfill these requirements, a 3D adaptive seismic isolation system has been designed with unique features. The telescope natural frequencies and damping change suddenly when the telescope is subjected to a 1-year return period seismic event, which is the maximum threshold acceleration acceptable without isolation. In the isolated configuration, the telescope frequencies range between 0.3 Hz (isolation frequency) and 30 Hz (highest frequency of interest), while in the fixed configurations the frequencies range between 2.6 Hz and 30Hz.
The vertical and horizontal acceleration reduction is obtained with special devices designed for this type of applications.
This paper presents the design and shows the results of the sophisticated nonlinear time history analyses performed on the DMS. The large finite element models consist of about 75000 nodes and over 110000 elements and include nonlinear spring damper elements calibrated experimentally to model the vertical and horizontal behavior of the seismic devices.
The ELT Telescope defines new levels of performances for all the engineering fields involved in the design and realization of the telescope. This is true also for the Telescope axes Control System that has to meet the requirements while guaranteeing robustness of the control loops and avoiding the resonances excitation.
The telescope requirements include slewing and offsetting time, trajectory rate limits, tracking accuracy, wind disturbances rejection and the avoidance of resonances excitation.
To evaluate the Control System behavior, a State Space Matrix has been estimated from the modal analysis of a finite element model of the complete telescope, including also the pier, in the “free rotor” condition.
The plant transfer functions of the Azimuth and Altitude axes have been analyzed to evaluate the more critical resonances that can affect the control loops bandwidth. The velocity and the position loops architectures have been designed and tuned to evaluate how the control bandwidth influences the structural resonances.
Different loops architectures have been implemented to compare the results, also including feedforward control to enhance the tracking performance and low pass filters to minimize the structural modes excitation. The control design results are presented.
A telescope model, including Azimuth and Altitude axes, frictions and motor torque disturbances, encoders quantization, loops sampling and latencies, has been created. The wind disturbance has been implemented as a time-varying force acting directly on the telescope structure, generated using a velocity time history with the requested PSD.
Several simulations, here presented, with and without the wind disturbance, have been done to analyze the performances respect to all the requirements and to assess the structural behavior. The simulations consider the axes moving at the same time to evaluate the cross coupling effect following all the foreseen trajectories.
KEYWORDS: Telescopes, Domes, Finite element methods, Space telescopes, 3D modeling, Servomechanisms, Control systems, Mirrors, Error analysis, Computer programming
The Extremely Large Telescope (ELT) is the largest near- and mid- infrared telescope of the world.
The performance check of the preliminary design of the ELT has been completed through a variety of analyses: structural static analysis (FEM), modal and harmonic analysis (FEM), seismic spectrum and transient analysis (FEM), wind analysis (CFD and Wind Tunnel Test), thermal analysis (FEM), vibration analysis (FEM + State Space model), Servo analysis for pointing and tracking (State Space model).
A FEM model of the telescope has been created to analyze the telescope behavior against all the significant actions: gravity, wind, seism, thermal, manufacturing and alignment errors. The model includes the telescope pier and the pier foundations.
A Wind Tunnel Test campaign has been carried out on a scaled model of the Dome and Telescope to assess the wind action on the structures. The campaign has been supported by a detailed CFD analysis with several cases of Dome orientation, Dome configuration, wind velocity and turbulence intensity.
A State Space model of the telescope has been set up to perform the Servo analysis of the azimuth and altitude control system. A comprehensive State Space model of the Dome, the Ground, and the Main Structure has been set up to perform the vibration analysis of the whole observatory (including the machinery in the auxiliary building and the erratic vibrations from the ground).
The present paper provides a synthetic description of the generated models and the most significant results.
The ELT Dome has been conceived for protecting the 39m ELT telescope, with its 86m base diameter and its almost 80m height. The rotating Dome is spherical to enhance the aerodynamic behavior; it weights about 6000 tons and it is provided with a 42m wide slit, to allow the telescope observation.
The bearing structure of the Dome is a truss structure made of steel, having a base ring and a series of arch girders as its main elements.
The Dome Rotation is performed by 36 trolleys, which are fixed to the top of the reinforced concrete Dome Base. Safety against seismic events is guaranteed by a dedicated Isolation and Damping System at the Dome Pier.
The Dome is covered by a custom Cladding System, that has been tailored in order to provide the required thermal insulation and withstand the harsh Environmental Conditions of the ELT Site.
With the aim of controlling the airflow around the Telescope, the ELT Dome is provided with a series of 89 Louvers, which are distributed among the rotating and the fixed structures. Besides, a Windscreen made of four permeable aluminum panels protects the Telescope; each panel spans over the 42m slit and is 10m high. The Windscreen is able to track with the Telescope on a 20 to 70deg range of the altitude angle.
The Auxiliary Building is a ring surrounding the Dome Pier and houses the Dome Technical Rooms, thus guaranteeing a radial distribution of all the Services. Among the Dome Supplies, a custom HVAC System is able to control the Telescope Chamber temperature with a ±2°C precision. The ELT Dome is provided with specific Plants so to supply Power to all the relevant loads and to the Electrical Equipment, as well as with a custom Global Control System and a series of Safety Systems.
The ELT, Extremely Large Telescope, a 40m class optical, near and mid-infrared telescope that will be installed on Cerro Armazones, on the Chilean Andes, will be characterized by a an alt-azimuthal steel structure mounting weighting about 3700 tons. The telescope design consists of a highly optimized, space-frame structure, whose deflection characteristics have been carefully tuned to facilitate the performance of the oil film associated with the hydrostatic bearing system and the performance of the rotation associated with the drive and encoder systems. The Altitude structure design incorporates the M1 Mirror cell and hosts all the telescope optics. The major challenges in the design are the need to keep the primary mirror segments within a reasonable range from the prescribed locations and the need to minimize the static and dynamic deflections of the secondary mirror. The telescope rotates on tracks fixed to a concrete pier with a diameter of about 52m, completely isolated from the ground by means of special seismic devices. Power, data, control cables and fluid hoses follow the azimuth range of 550 degrees by means of the 18m diameter cable wrap, and the altitude range of 96 degrees with two lateral cable drapes. The rotation of the Azimuth and Altitude axes are possible thanks to the Direct Drive System and kept in place by high precision incremental tape encoders. The telescope is equipped with a very performing Control System that implements state of the art automation technologies, such as isochronous real time fieldbus, communication protocols, absolute time synchronization and safety, state of the art software engineering methods, such as object oriented design and iterative AGILE software development methodology.
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