Auxiliary free space optical communication project to ensure continuous transfer of data for DAG the 4m telescope

The 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.Publisher's Versio

DAG-SLODAR (SLOpe Detection And Ranging) Teleskobu

Atmosferin astronomik gözlemlere olan olumsuz etkilerini alt etmek üzere geliştirilmiş ve DAG teleskobunda da kullanılacak olan Adaptif Optik (AO) sistemleri, türbülansın ayrıntılı bir şekilde karakterize edilmesine ihtiyaç duyar. SLODAR, atmosferik optik türbülansın dikey profilini, iki yakın yıldızın Shack-Hartmann dalgacephesi algılayıcısı (SH-WFC) ile yapılan dalgacephesi eğimi ölçümlerinin çapraz korelasyonundan elde eden bir yöntemdir. SLODAR sistemi, küçük çaplı (∼50cm) bir teleskobun odak düzlemine yerleştirilen, iki SH-WFC barındıran SLODAR aygıtından oluşur. Paranal, La Palma, Mauna Kea ve SAAO gözlemevlerinde kurulan SLODAR teleskopları "yer katmanı (ground layer)" olarak adlandırılan ve yerleşkenin üzerindeki ilk kilometre içindeki türbülansı ölçmek amacıyla kullanılmışlardır. Bu sunumda DAG yerleşkesinde kurulmakta olan SLODAR sisteminden bahsedilecektir.Publisher's Versio

Observatory building design: A case study of DAG with infrastructure and facilities

Eastern 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.Publisher's Versio

DAG: A new observatory and a prospective observing site for other potential telescopes

DAG (Eastern Anatolia Observatory is read as "Dogu Anadolu Gözlemevi" in Turkish) is the newest and largest observatory of Turkey, constructed at an altitude of 3150 m in Konakll/Erzurum provenience, with an optical and nearinfrared telescope (4 m in diameter) and its robust observing site infrastructure. This national project consists of three main phases: DAG (Telescope, Enclosure, Buildings and Infrastructures), FPI (Focal Plane Instruments and Adaptive Optics) and MCP (Mirror Coating Plant). All these three phases are supported by the Ministry of Development of Turkey and funding is awarded to Atatürk University. Telescope, enclosure and building tenders were completed in 2014, 2015 and 2016, respectively. The final design of telescope, enclosure and building and almost all main infrastructure components of DAG site have been completed; mainly: road work, geological and atmospheric surveys, electric and fiber cabling, water line, generator system, cable car to summit. This poster explains recent developments of DAG project and talks about the future possible collaborations for various telescopes which can be constructed at the site.Publisher's Versio

Türkiye’deki Astronomik Gözlemevlerinin Kuruluş Yerlerinin Bulanık AHS ile Değerlendirilmesi

Gözlemevi kuruluş yeri kararı, yapılan incelemeler ve toplanan veriler uzmanlar tarafında değerlendirilerek yapılmaktadır. Yapılan bu çalışmada hali hazırda Türkiye’de konumlanmış gözlemevleri kuruluş yerleri açısından çok kriterli karar verme yöntemi ile değerlendirilmektedir. Değerlendirme sürecinde nitelik olarak meteorolojik, coğrafi ve antropojenik nitelikler ele alınmıştır. Belirlenen alternatifler ise Ulupınar Gözlemevi, Ege Üniversitesi Gözlemevi, TÜBİTAK Ulusal Gözlemevi, Ankara Üniversitesi Kreiken Gözlemevi ve Doğu Anadolu Gözlemevi olarak belirlenmiştir. Bu kriter ve alternatiflere bulanık analitik hiyerarşi süreci (AHS) uygulanarak ülkemizdeki gözlemevlerinin konum değerlendirilmesinin yapılması amaçlanmıştır. Karar analizi sonucunda seçilen kriterlere bağlı olarak mevcut gözlemevlerinin kuruluş yerleri ile ilgili değerlendirmeler elde edilmiştir

Turkey's next big science project: DAG the 4 meter telescope

The 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.Publisher's Versio

Modelling and simulation studies on adaptive controller for alt-azimuth telescopes despite unknown wind disturbance and mass

Numerous ground-based observatories are using small sized ground telescopes for scientific research purposes. The telescopes that are available on the market have three main problems. These issues can be listed as: positioning repeatability, tuning requirement according to different wind speeds for different seasons, and the mass changing via different scientific equipments added to the telescope. This study is aimed at resolving these issues for ground based small alt-azimuth telescopes. Establishing of a set and forget system is performed by designing an adaptive controller. Motor dynamics are taken into consideration for a realistic mathematical model. The Wind-Gust model that consists of a sum of sinusoidal disturbances with unknown phase, amplitude and frequency is used for the wind model. The purposed controller cancels the disturbance effects on the plant while operational positioning and also the makes the plant insensitive to mass changes. The Lyapunov approach is utilised when proving the asymptotic stability. The proposed controller’s success is illustrated with thorough numerical evaluation.The authors would like to thank the technical guidance and funding support of Isik University, Center for Optomechatronics Research and Application (OPAM),and Ataturk University Center for Astrophysical Application and Research (ATASAM). The author(s) received no financial support for the research, authorship, and/or publication of this article.Publisher's Versio

A flexible adaptive optics concept for general purpose high angular resolution science on the DAG 4m telescope

Thanks to the availability of high actuator density deformable mirrors (ALPAO 468 DM), the high versatility of the pyramid wavefront sensor and above all, the venue of essentially no noise EMCCD detectors, it becomes possible to fully adapt the degree of correction of an adaptive optics system for a given guide star brightness and atmospheric condition. Indeed, when the conditions are very good, the high actuator density of the DM allows to reach a high Strehl by using all the modes, and when the conditions are less favorable, the spatial sampling, i. the number of modes, and the sensitivity of the detector allows to maximize the Strehl beyond what would be possible with a classical, frozen SH-WFS based system. Beside, oversampling the detector allows to relax the specification on the pupil images given by the pyramid on the detector, which in turn relaxes the pyramid prism manufacturing specifications. We are now designing an AO system for the DAG 4 m telescope that will allow, on the same system, ExAO as well as low order improved seeing observations. This article reports on the AO performance analysis, the final optical design and the design of the double prism achromatic pyramid.Publisher's Versio

Project management of DAG: Eastern Anatolia Observatory

The 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.Publisher's Versio

Agile development approach for the observatory control software of the DAG 4m telescope

Observatory Control Software for the upcoming 4m infrared telescope of DAG (Eastern Anatolian Observatory in Turkish) is in the beginning of its lifecycle. After the process of elicitation-validation of the initial requirements, we have been focused on preparation of a rapid conceptual design not only to see the big picture of the system but also to clarify the further development methodology. The existing preliminary designs for both software (including TCS and active optics control system) and hardware shall be presented here in brief to exploit the challenges the DAG software team has been facing with. The potential benefits of an agile approach for the development will be discussed depending on the published experience of the community and on the resources available to us