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Yayın Integrated opto-dynamic modeling of the 4-m DAG telescope image quality performance(SPIE-Int Soc Optical Engineering, 2016) Zago, Lorenzo; Guex, Benjamin; Yeşilyaprak, Cahit; Yerli, Sinan Kaan; Keskin, OnurThe Turkish DAG 4-m telescope is currently through the final design stage. It is to be located on a 3170 m mountain top in Eastern Anatolia. The telescope will be a state-of-The art device, alt-Az mount with active primary and adjustable secondary and tertiary mirrors. Its optics design is specially aimed at being compatible with advance adaptive optics instrumentation. The ultimate performance of such a telescope results of multiple concurrent effects from many different components and active functions of the complex system. The paper presents a comprehensive integrated (end-To-end) model of the telescope, comprising in one computational sequence all structural, electrodynamics and oactive optics performance that produce the image quality at the focal plane. The model is entirely programmed in Matlab/Simulink and comprises a finite element model of structure and mirrors, dynamics modal reduction, deformation analyses of structural and optical elements, active optics feedback control in the Zernike modal space.Yayın Status of the Focal Plane Instrumentation (FPI) Project of the 4 m DAG Telescope(SPIE, 2016-08-09) Keskin, Onur; Yerli, Sinan Kaan; Yeşilyaprak, Cahit; Güver, Tolga; Aliş, Sinan; Yelkenci, Filiz Korhan; Güçsav, Bülent Burak; Arabacı, Mehtap Özbey; Erol, AyşeDAG (Eastern Anatolia Observatory in Turkish) will be the newest and largest (4m) observatory of Turkey in both optical (VIS) and near-infrared (NIR) Owith its robust observing site infrastructure. The telescope is designedOto house 2 Nasmyth platformes which will be dedicated to NIR and VIS observations. A collaboration has recently been established among four Turkish universities including FMV Isik University (for adaptive optics systems), Middle East Technical University (fort measurement, test and calibration purposes), Istanbul University (for new technology instruments, e.g. MKIDs) and as the coordinator Ataturk University (for obtaining NIR and VIS instruments). In this paper the status of the recently approved FPI project and its aims are presented and possible collaboration opportunities are emphasized.Yayın Turkey's next big science project: DAG the 4 meter telescope(SPIE-INT Soc Optical Engineering, 2014) Keskin, Onur; Yeşilyaprak, Cahit; Yerli, Sinan Kaan; Zago, Lorenzo; Jolissaint, LaurentThe DAG (Turkish for Eastern Anatolia Observatory) 4-m telescope project has been formally launched in 2012, being fully funded by the Government of Turkey. This new observatory is to be located on a 3170 m altitude ridge near the town of Erzurum in Eastern Anatolia. First light is scheduled for late 2017. The DAG team's baseline design of the telescope consists of a Ritchey-Chretien type with alt-az mount, a focal length of 56 m and a field of view up to 30 arcmin. Multiple instruments will be located at the Nasmyth foci. The optical specifications of the telescope are set by DAG team for diffraction limited performance with active and adaptive optics. Modern mirror control technologies will allow defining in a most cost effective way the figuring requirements of the optical surfaces: the low order figuring errors of the combined optical train constituted of M1-M2-M3 are defined in terms of Zernike coefficients and referred to the M1 surface area. The high order figuring errors are defined using the phase structure functions. Daytime chilling of the closed enclosure volume and natural ventilation through suitable openings during observations will be used to ensure optimal mirror and dome seeing. A design of a ground layer adaptive optics (GLAO) subsystem is developed concurrently with the telescope. In this paper, main design aspects, the optical design and expected performance analysis of the telescope will be presented.Yayın The design of an adaptive optics telescope: the case of DAG(SPIE, 2016-07-27) Jolissaint, Laurent; Keskin, Onur; Zago, Lorenzo; Yerli, Sinan Kaan; Yeşilyaprak, Cahit; Mudry, Emeric; Lousberg, Grégory P.In this paper, we describe in detail the optical design of DAG, a new 4 m telescope for Turkey. DAG is an "adaptive optics friendly" telescope, in a sense that each design decision is taken considering the potential impact on the AO performance (vibrations, static aberrations etc.) The objective is to make this telescope fully ready for AO at first light. It is designed as a Ritchey-Chretien combination, 56 m focal length, with Nasmyth foci only, and active optics. Its total RMS error is expected to be 45 nm up to Zernike mode 78, and 26 nm for the higher, non AO corrected modes. A final design optimization has been done by the telescope manufacturers, demonstrating that our AO-based requirements can be satisfied, without much difficulty.Yayın Observatory building design: A case study of DAG with infrastructure and facilities(SPIE, 2016-08-19) Şahmalı, Ali Erkan; Yeşilyaprak, Cahit; Yerli, Sinan Kaan; Keskin, OnurEastern Anatolian Observatory (DAG), will be built in one of the well-known mountain ridges of Erzurum, Turkey, at latitude of 39°46'50, longitude of 41°13'35 and an altitude of 3.151 meters. As well as erecting the largest telescope of Turkey, the DAG project aims to establish an observatory complex both small in size and functional enough to give service to all astronomy community. In this paper, the challenge is explained in details: geological and geographical limitations, environmental and meteorological constraints, engineering and structural considerations, energy efficiency and sustainability.Yayın Eastern Anatolia Observatory (DAG): Recent developments and a prospective observing site for robotic telescopes(Universidad Nacional Autonoma Mexico Instituto Astronomia, 2016) Yeşilyaprak, Cahit; Yerli, Sinan Kaan; Keskin, OnurThis document (Eastern Anatolia Observatory (DAG) is the new observatory of Turkey with the optical and near-infrared largest telescope (4 m class) and its robust observing site infrastructure. This national project consists of three phases with DAG (Telescope, Enclosure, Buildings and Infrastructures), FPI (Focal Plane Instruments and Adaptive Optics) and MCP (Mirror Coating Plant) and is supported by the Ministry of Development of Turkey. The tenders of telescope and enclosure have been made and almost all the infrastructure (roads, geological and atmospherical surveys, electricity, fiber optics, cable car, water, generator, etc.) of DAG site (Erzurum/Turkey, 3,170 m altitude) have been completed. This poster is about the recent developments of DAG and about the future possible collaborations for various robotic telescopes which can be set up in DAG site.Yayın DAG telescope site studies and infrastructure for possible international co-operations(SPİE-INT Soc Optical Engineering, 2016) Yerli, Sinan Kaan; Yeşilyaprak, Cahit; Keskin, Onur; Aliş, SinanThe selected site for the 4 m DAG (Eastern Anatolian Observatory in Turkish) telescope is at "Karakaya Ridge", at 3170 m altitude (3150 m after summit management). The telescope's optical design is performed by the DAG technical team to allow infrared observation at high angular resolution, with its adaptive optics system to be built in Turkey. In this paper; a brief introduction about DAG telescope design; planned instrumentation; the meteorological data collected from 2008, clear night counts, short-term DIMM observations; current infrastructure to hold auxiliary telescopes; auxiliary buildings to assist operations; the observatory design; and coating unit plans will be presented along with possible collaboration possibilities in terms of instrumentation and science programs.Yayın Design of a derotator for the 4 m DAG telescope(SPIE-Int Soc Optical Engineering, 2016-08-09) Baudet, Jeremie; Jolissaint, Laurent; Keskin, Onur; Yeşilyaprak, Cahit; Yerli, Sinan KaanThis paper Silt our work on the design of a field derotator for the adaptive optics instruments platform of DAG (Dogu Anadolu Cozier vi), a new 4 in telescope for astronomical observations near the city of krzurum, l'urkey. While the telescopefollows an astronomical object, its pupil sees a rotation of the object around the optical axis which depends n the telescope geographic coordinate and the object sky coordinate. This effect is called the field rotation. This rotation needs to be compensated during the astronomical object data acquisition. In this report we demonstrate the feasibility of placing the derotator (a. K-mirror design) in the telescope fork central hole and propose a preliminary design, considering flexures.Yayın Auxiliary free space optical communication project to ensure continuous transfer of data for DAG the 4m telescope(SPIE, 2016) Keskin, Onur; Yeşilyaprak, Cahit; Yerli, Sinan KaanThe continuity of the amount of data that the 4m DAG (Eastern Anatolia Observatory in Turkish) telescope will produce and transfer to Ataturk University is critical not to jeopardize the science programs. Though the fiber optics and radio link infrastructures are in place, these systems are still volatile against earthquakes, and possible excavation damages. Thus the 4m DAG telescope will be equipped with a free space optical communication system to ensure the continuity of the data transfer as a backup system. In order to cope with the disturbances introduced by the atmospheric turbulence, the transceiver FSO system will be equipped with a wavefront corrector. In this paper, the Cassegrain optical design, and working principle of this system as well as expected performance analyses will be presented.Yayın Project management of DAG: Eastern Anatolia Observatory(SPIE, 2016) Keskin, Onur; Yeşilyaprak, Cahit; Yerli, Sinan Kaan; Zago, Lorenzo; Güver, Tolga; Aliş, SinanThe four meter DAG (Eastern Anatolia Observatory in Turkish) telescope is not only the largest telescope in Turkey but also the most promising telescope in the northern hemisphere with a large potential to offer scientific observations with its cutting edge technology. DAG is designed to be an AO telescope which will allow both infrared and visible observations with its two Nasmyth platforms dedicated to next generation focal plane instruments. In this paper, status updates from DAG telescope will be presented in terms of; (i) in house optical design of DAG, (ii) tender process of telescope, (iii) tender process of enclosure, and (iv) tender process of the observatory building. Also status updates from the focal plane instruments project and possible collaboration activities will be presented.
