This PDF file contains the front matter associated with SPIE Proceedings Volume 8444, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

The 1.6-m New Solar Telescope (NST) has been used to observe the Sun for more than three years with ever increasing capabilities as its commissioning phase winds down. The NST is the first facility-class solar telescope built in the U.S. in a generation, and it has an off-axis design as is planned for the 4 m Advanced Technology Solar Telescope. Lessons learned will be discussed. Current NST post-focus instrumentation includes adaptive optics (AO) feeding photometric and near-IR polarimetric sytems, as well as an imaging spectrograph. On-going instrumentation projects will be sketched, including Multi-Conjugate AO (MCAO), next generation (dual Fabry- Perot) visible light and near-IR polarimeters and a fully cryogenic spectrograph. Finally, recent observational results illustrating the high resolution capabilities of the NST will be shown.

This paper presents the applications of infrared techniques in National Vacuum Solar Telescope(NVST) .We give a brief introduction to infrared thermography for nondestructive evaluation, especially for the measurement of mirror temperature gradient and the dome temperature distribution. The results give us more reference for the Mirror Seeing and Dome Seeing improvement.

In order to detect the fine structures of solar magnetic field and dynamic field, an 8 meter solar telescope has been proposed by Chinese solar community. Due to the advantages of ring structure in polarization detection and thermal control, the current design of CGST (Chinese Giant Solar Telescope) is an 8 meter ring solar telescope. The spatial resolution of CGST is equivalent to an 8 meter diameter telescope, and the light-gathering power equivalent to a 5 meter full aperture telescope. The integrated simulation of optical system and imaging ability such as optical design, MCAO, active maintenance of primary mirror were carried out in this paper. Mechanical system was analyzed by finite element method too. The results of simulation and analysis showed that the current design could meet the demand of most science cases not only in infrared band but also in near infrared band and even in visible band. CGST was proposed by all solar observatories in Chinese Academy of Sciences and several overseas scientists. It is supported by CAS and NSFC (National Natural Science Foundation of China) as a long term astronomical project.

Movies with fields-of-view larger than normal for high-resolution telescopes will give a better understanding of processes on the Sun, such as filament and active region developments and their possible interactions. New active regions can influence, by their emergence, their environment to the extent of possibly serving as an igniter of the eruption of a nearby filament. A method to create a large field-of-view is to join several fields-of-view into a mosaic. Fields are imaged quickly one after another using fast telescope-pointing. Such a pointing cycle has been automated at the Dutch Open Telescope (DOT), a high-resolution solar telescope located on the Canary Island La Palma. The observer can draw with the computer mouse the desired total field in the guider-telescope image of the whole Sun. The guider telescope is equipped with an H-alpha filter and electronic enhancement of contrast in the image for good visibility of filaments and prominences. The number and positions of the subfields are calculated automatically and represented by an array of bright points indicating the subfield centers inside the drawn rectangle of the total field on the computer screen with the whole-sun image. When the exposures start the telescope repeats automatically the sequence of subfields. Automatic production of flats is also programmed including defocusing and fast motion over the solar disk of the image field. For the first time mosaic movies were programmed from stored information on automated telescope motions from one field to the next. The mosaic movies fill the gap between whole-sun images with limited resolution of synoptic telescopes including space instruments and small-field high-cadence movies of high-resolution solar telescopes.

The National Solar Observatory’s (NSO) Advanced Technology Solar Telescope (ATST) is the first large U.S. solar telescope accessible to the worldwide solar physics community to be constructed in more than 30 years. The 4-meter diameter facility will operate over a broad wavelength range (0.35 to 28 μm ), employing adaptive optics systems to achieve diffraction limited imaging and resolve features approximately 20 km on the Sun; the key observational parameters (collecting area, spatial resolution, spectral coverage, polarization accuracy, low scattered light) enable resolution of the theoretically-predicted, fine-scale magnetic features and their dynamics which modulate the radiative output of the sun and drive the release of magnetic energy from the Sun’s atmosphere in the form of flares and coronal mass ejections. In 2010, the ATST received a significant fraction of its funding for construction. In the subsequent two years, the project has hired staff and opened an office on Maui. A number of large industrial contracts have been placed throughout the world to complete the detailed designs and begin constructing the major telescope subsystems. These contracts have included the site development, AandE designs, mirrors, polishing, optic support assemblies, telescope mount and coudé rotator structures, enclosure, thermal and mechanical systems, and high-level software and controls. In addition, design development work on the instrument suite has undergone significant progress; this has included the completion of preliminary design reviews (PDR) for all five facility instruments. Permitting required for physically starting construction on the mountaintop of Haleakalā, Maui has also progressed. This paper will review the ATST goals and specifications, describe each of the major subsystems under construction, and review the contracts and lessons learned during the contracting and early construction phases. Schedules for site construction, key factory testing of major subsystems, and integration, test and commissioning activities will also be discussed.

The Advanced Technology Solar Telescope (ATST) is a 4-m class solar telescope to be built at the Haleakalā High Altitude Observatory Site in Maui, Hawai'i. It will be the largest solar telescope in the world, with unprecedented abilities to view details of the Sun. Using adaptive optics technology, ATST will be able to provide the sharpest views ever taken of the solar surface. It is expected that the 4-meter class telescope will have a significant impact on the study of stellar magnetic fields, plasma physics and astronomy, allowing scientists to learn even more about the Sun and solarterrestrial interactions. The ATST enclosure is unique in its functionality, as not only it provides protection from adverse weather conditions when not in operation, but it also positions the telescope Aperture Stop which must be accurately aligned so that the primary mirror is fully illuminated, while insolation in other telescope equipment is prevented. The proposed design is based on a multi-sector shutter system arrangement with an innovative crawler drive system (patent pending) assembled on two steel fabricated arch girders. These arch girders are stiffened by a secondary structure and supported on a steel fabricated base ring. The base ring rests on an azimuth mechanism composed of several driven/idling bogies. The outer shape of the enclosure is configured by the secondary structure which supports the cladding and has been selected so as to minimize the solar irradiated surface and reduce shell seeing in early morning hours when the seeing is the best. This paper describes the work performed by AEC IDOM and ATST team to define both the final design of the Enclosure and the construction plan to erect it at the Observatory Site.

L-3 Integrated Optical Systems (IOS) Division has been selected by the National Solar Observatory (NSO) to design and produce the Top End Optical Assembly (TEOA) for the 4-meter Advanced Technology Solar Telescope (ATST) to operate at Haleakalā, Maui. ATST will perform to a very high optical performance level in a difficult thermal environment. The TEOA, containing the 0.65-meter silicon carbide secondary mirror and support, mirror thermal management system, mirror positioning and fast tip-tilt system, field stop with thermally managed heat dump, thermally managed Lyot stop, safety interlock and control system, and support frame, operates in the "hot spot" at the prime focus of the ATST and so presents special challenges. In this paper, we describe progress in the L-3 technical approach to meeting these challenges, including silicon carbide off-axis mirror design, fabrication, and high accuracy figuring and polishing all within L-3; mirror support design; the design for stray light control; subsystems for opto-mechanical positioning and high accuracy absolute mirror orientation sensing; Lyot stop design; and thermal management of all design elements to remain close to ambient temperature despite the imposed solar irradiance load.

The ATST Telescope Mount Assembly uses for the Azimuth axes mechanisms bearing and drive technologies as developed for the machine tool industry. An overview on the ATST mount project and design and its verification by analysis, simulation and tests are given in two separate papers of this conference. This paper describes the main design and accuracy features of the bearing and drive subsystems, their adaption to the ATST mount and their influence on the telescope structural design, and gives a hint to the challenges in the upcoming manufacturing, installation and commissioning phases.

After a brief introduction of what is the Dark Energy Survey (DES) project and which optical instrumentation will be used, the presentation will be mainly focused onto the optical production of the large lenses (up to 1m diameter) constituting the DES Camera (DECAM) located at the focal plane of the main observing telescope. Special emphasis will be made onto the optical manufacturing issues and interferometric testing solutions, including compensation of index inhomogeneities, which have been carried out by THALES SESO especially for the biggest entrance lens (very challenging CV/CX meniscus named C1). Through several examples of typical past realizations or future possible ones for different astronomical projects requiring 1m-class optics, the presentation will conclude by a brief over review of the corresponding existing "state of the art" at THALES SESO for these technologies.

The Transneptunian Automated Occultation Survey (TAOS II) will aim to detect occultations of stars by small ( 1 km diameter) objects in the Solar System and beyond. Such events are very rare (< 10⁻³ events per star per year) and short in duration ( 200 ms), so many stars must be monitored at a high readout cadence. TAOS II will operate three 1.3 meter telescopes at the Observatorio Astron´omico Nacional at San Pedro Martir in Baja California, Mexico. With a 2.3 square degree field of view and a high speed camera comprising CMOS imagers, the survey will monitor 10,000 stars simultaneously with all three telescopes at a readout cadence of 20 Hz.

NGTS is a new ground-based transit survey aimed at detecting sub-Neptune sized exoplanets around bright stars. The instrument will be installed at the ESO Paranal observatory in order to benefit from the excellent observing conditions and follow-up synergy with the VLT and E-ELT. It will be a robotic facility composed of 12, 200 mm telescopes equipped with 2Kx2K NIR sensitive detectors. It is built on the legacy of the WASP experience.

The European Space Agency, in the framework of its Space Situational Awareness (SSA) Preparatory Programme, has commissioned a study for a global network of surveillance telescopes to monitor the ever increasing number of objects in Earth orbit. A possible scenario identified by the study is a network of 20 SSA Telescopes located at various observatory sites. This paper presents the conceptual design of a telescope system optimised for wide field, short exposures and fast tracking – all requirements of SSA. The requirements of the SSA telescope will be presented followed by a brief review of potential telescope technologies. Following a trade study analysis a 1 m compact Schmidt telescope design was chosen. This design provides a field of view of 3.4 degrees diameter. The design is achromatic and covers the wavelength range 380 – 900 nm. The sensitivity of the telescope is such that it can monitor the orbital parameters of objects as small as 1 cm in low Earth orbit. This is equivalent to 17^th magnitude in 0.07 seconds at a signal to noise ratio of 5. The telescope is mounted on an Altitude- Azimuth type mount that enables wide coverage of the sky and fast tracking speeds. The entire telescope is contained within a Calotte type enclosure. The camera, detector control, and telescope control system design will also be presented. Systems engineering aspects will be addressed, with particular attention given to the analysis and flow-down of requirements and a practical and pragmatic process of system-level design trade-offs.

AMOS S.A. is in charge of the development of the telescopes for the "Observatorio Astrofisico de Javalambre" in Spain where a 2.6 m wide field telescope is complemented by an 80 cm telescope. This paper focuses on the 2.6 m telescope Javalambre Survey Telescope (JST): it is combining a large collecting surface with a wide field of view for reaching a vast portion of the sky, which is the most relevant parameter for surveys, while ensuring an optical image quality compatible with the site seeing and a suitable depth in the sky sighting. The major difficulty consists in maintaining the image quality over a 500 mm focal plane. A good design is the result of a thorough multidisciplinary optimization process where the fabrication constraints are a major driving parameter. The complexity of the system led to elaborate innovative solutions for the closed loop control of both image quality and tracking features. The design and the methodology of working are presented in details. The optics fabrication, the integration and acceptance tests are also reviewed.

The PS2 telescope is the second in an array of wide-field telescopes that is being built for the Panoramic-Survey Telescope and Rapid Response System (Pan-STARRS) on Haleakala. The PS2 design has evolved incrementally based on lessons learned from PS1, but these changes should result in significant improvements in image quality, tracking performance in windy conditions, and reductions in scattered light. The optics for this telescope are finished save for their coatings and the fabrication for the telescope structure itself is well on the way towards completion and installation on-site late this year (2012). The most significant differences between the two telescopes include the following: secondary mirror support changes, improvements in the optical polishing, changes in the optical coatings to improve throughput and decrease ghosting, removal of heat sources inside the mirror cell, expansion of the primary mirror figure control system, changes in the baffle designs, and an improved cable wrap design. This paper gives a description of each of these design changes and discusses the motivations for making them.

The Multi-site All-sky CAmeRA MASCARA is an instrument concept consisting of several stations across the globe, with each station containing a battery of low-cost cameras to monitor the near-entire sky at each location. Once all stations have been installed, MASCARA will be able to provide a nearly 24-hr coverage of the complete dark sky, down to magnitude 8, at sub-minute cadence. Its purpose is to find the brightest transiting exoplanet systems, expected in the V=4-8 magnitude range - currently not probed by space- or ground-based surveys. The bright/nearby transiting planet systems, which MASCARA will discover, will be the key targets for detailed planet atmosphere observations. We present studies on the initial design of a MASCARA station, including the camera housing, domes, and computer equipment, and on the photometric stability of low-cost cameras showing that a precision of 0.3-1% per hour can be readily achieved. We plan to roll out the first MASCARA station before the end of 2013. A 5-station MASCARA can within two years discover up to a dozen of the brightest transiting planet systems in the sky.

The 3.5-meter diameter Large Synoptic Survey Telescope (LSST) secondary (M2) mirror utilizes a 100mm thick meniscus ULE™ blank completed by Corning Incorporated in 2009. Sub-aperture interferometry will guide the polishing process to meet mirror structure function requirements. The convex asphere is actively supported by 72 axial actuators and 6 tangential links. These tangent links utilize an embedded lever system to meet the requirements. The axial actuators have force limiting devices. The control system utilizes a higher level "outer loop controller" for monitoring and commanding the tangent links and axial actuators. Numerous sensors determine the assembly status. To prevent thermally induced image degradation, the interior air of the M2 cell is conditioned.

The Hobby-Eberly Telescope (HET) is an innovative large telescope of 9.2 meter aperture, located in West Texas at the McDonald Observatory (MDO). The HET operates with a fixed segmented primary and has a tracker which moves the four-mirror corrector and prime focus instrument package to track the sidereal and non-sidereal motions of objects. A major upgrade of the HET is in progress that will increase the pupil size to 10 meters and the field of view to 22′ by replacing the corrector, tracker and prime focus instrument package. In addition to supporting the existing suite of instruments, this wide field upgrade will feed a revolutionary new integral field spectrograph called VIRUS, in support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEXχ). This paper discusses the current status of this upgrade.

The Advanced Technology Solar Telescope (ATST) will be the largest solar telescope in the world with a 4m aperture primary mirror. The off axis nature of the telescope optical layout, has the proportions of an 8 metre class telescope. Accordingly the instrumentation for solar observations a 16m diameter co-rotating laboratory (Coude Rotator) is also located within the telescope pier. The pier has a lower cylindrical profile with an upper conical section to support both the telescope mount with a 9m bearing diameter and contain the 16m diameter Coudé rotator. The performance of this pier cannot be considered in isolation but must account for ancillary equipment, access and initial installation. The Coude rotator structure and bearing system are of similar size to the telescope base structure and therefore this is the proverbial 'ship in a bottle' problem. This paper documents the competing requirements on the pier design and the balancing of these as the design progresses. Also summarized is the evolution of the design from a conceptual traditional reinforced concrete pier to a composite concrete and steel framed design. The stiffness requirements of the steel frame was a unique challenge for both the theoretical performance and overall design strategy considering constructability. The development of design acceptance criteria for the pier is discussed along with interfacing of the AandE firm responsible for the pier design and the telescope designer responsible for the telescope performance.

The EST has unique an optical layout, with an on-axis Gregorian tube system and the altitude axis behind the M1 mirror unit - a great challenge for the mount designer in regard of balancing. Three different structural design concepts and various alternatives for the bearing and drive systems were investigated. Hydrostatic bearings with direct drives are compared with roller bearings and geared drives. The influence of available bearing and drive technology were investigated by FE calculations, dynamic analysis and end-to-end simulations. The finally recommended design concept is based on large-diameter segmented roller bearings and so-called pinion motors in both axes.

The Giant Magellan Telescope (GMT), one of several next generation Extremely Large Telescopes (ELTs), is a 25.4 meter diameter altitude over azimuth design set to be built at the summit of Cerro Campanas at the Las Campanas Observatory in Chile. The primary mirror consists of 7 individual 8.4 meter diameter segments resulting in an equivalent collecting area of a 21.5 meter diameter single mirror. The telescope structure, optics and instrumentation has a rotating mass of approximately 1250 metric tons and stands approximately 40 meters tall. This paper reports the results of our ongoing preliminary design and development of the GMT structure and its major mechanical and opto-mechanical components. A major recent redesign of the Gregorian Instrument Rotator (GIR) resulted in significant changes to the telescope structure and several mechanisms. Design trade studies of various aspects of the main structure, hydrostatic bearing system, main axes drives, M2 positioner, M3 subsystem and the corrector-ADC subsystem have refined the preliminary design in these areas.

The European Extremely Large Telescope (E-ELT) is the biggest telescope in the world. Within the Detailed Design activities, ESO has awarded EIE GROUP (European Industrial Engineering) a contract for the Design of the Main Structure to the point where the concept of the telescope has been consolidated, from a construction point of view. All the Design activities have been developed in order to create an integrated system in terms of functionality and performance, while the engineering activities have been performed with the aim of obtaining a telescope that can be built, transported, integrated, with a reduced maintainability.

During the last two years a modified baseline design for the E-ELT was developed. The aim of this revision was both to achieve a significant cost saving and to reduce risk on major items. The primary mirror diameter was slightly reduced to 39 m and the total height of the telescope also decreased accordingly. This paper describes the work performed by IDOM under contract with ESO to review the EELT dome and foundations design to match the modified baseline. Detailed design and construction planning, as well as detailed cost estimates were updated for the 39-metre baseline design. In June 2011, ESO Council formally endorsed this modified design as the E-ELT revised baseline. Key redesign drivers are explained and final redesign details of all major subsystems are outlined. In general, the original compact dome design philosophy is maintained and adapted to the new dimensions. Cost optimisation strategies are applied throughout the detailed design update process. Special attention is also given to some specific new items now included in the modified baseline, such as the special ad-hoc seismic base isolation system for the telescope foundation.

Further to the re-dimensioning of the E-ELT (European Extremely Large Telescope) telescope to 37 metres, the project of the dome has been completely reviewed, together with the Auxiliary Building and the Foundations. The Dome is now constituted by a structure with a steel hemispherical architecture, 79m.-high, with a 101m.-external pier diameter and a 42m-wide observing slit. These dimensions require the application of technologies for big structures (like stadiums, hangars, etc.) in order to comply with the manufacturing, transport and assembly constrains. The dome is characterized by an agglomerate of mechathronic technologies originated by the long experience matured by EIE in the industrial and astronomical fields. The solutions adopted for the NTT, the VLT, the LBT, the VST and the VISTA have demonstrated, along the years of service, their functionality, as well as their reliability and maintainability. Moreover, innovative technologies have been introduced, especially for what concerns the rotation systems of the Dome, the louvers, the windscreen, etc. The architecture of the control systems has been completed re-formulated, and they are now able to manage in real time all the exigencies of the E-ELT Observatory. All Project phases have been properly analysed and simulated, guaranteeing the completeness of the constructability and the maintainability. The entire work has been developed in close cooperation with ESO Project Team, further to a specific contract.

The Large Synoptic Survey Telescope will be located on a seismically active Chilean mountain. Seismic ground accelerations produce the telescope's most demanding load cases. Consequently, accurate prediction of these accelerations is required. These seismic accelerations, in the form of Peak Spectral Acceleration (PSA), were compared for site specific surveys, the Chilean building codes and measured seismic accelerations. Methods were also investigated for adjusting for variations in damping level and return period. The return period is the average interval of time between occurrences of a specific intensity.

The Large Synoptic Survey Telescope (LSST) will be located on the seismically active Chilean mountain of Cerro Pachón. The accelerations resulting from seismic events produce the most demanding load cases the telescope and its components must withstand. Seismic ground accelerations were applied to a comprehensive finite element analysis (FEA) model which included the telescope, its pier and the mountain top. Response accelerations for specific critical components (camera and secondary mirror assembly) on the telescope were determined by applying seismic accelerations in the form of Power Spectral Densities (PSD) to the FEA model. The PSDs were chosen based on the components design lives. Survival level accelerations were determined utilizing PSDs for seismic events with return periods 10 times the telescope's design life which is equivalent to a 10% chance of occurring over the lifetime. Since the telescope has a design life of 30 years it was analyzed for a return period of 300 years. Operational level seismic accelerations were determined using return periods of 5 times the lifetimes. Since the seismic accelerations provided by the Chilean design codes were provided in the form of Peak Spectral Accelerations (PSA), a method to convert between the two forms was developed. The accelerations are also affected by damping level. The LSST incorporates added damping to meets its rapid slew and settle requirements. This added damping also reduces the components' seismic accelerations. The analysis was repeated for the telescope horizon and zenith pointing. Closed form solutions were utilized to verify the results.

The GMT (Giant Magellan Telescope) is a large ground-based telescope for astronomical research at optical and infrared wavelengths. The telescope is enclosed inside an Enclosure that rotates to follow the tracking of the telescope. The Enclosure is equipped with adjustable shutters and vents to provide maximum ventilation for thermal control while protecting the telescope from high wind loads, stray light, and severe weather conditions. The project will be built at Las Campanas Observatory in Chile on Cerro Las Campanas. The first part of this paper presents the wind tunnel test data as well as CFD (Computational Fluid Dynamics) study results for the GMT Enclosure. The wind tunnel tests include simulations for: a) Topography, b) Open Enclosure (all the shutters and vents open), and c) Closed Enclosure (all the vents and shutters closed). The CFD modeling was carried out for a wide range of conditions such as low and high wind speeds at various wind directions, and for the fully open and partially open Enclosure. The second part of this paper concerns the thermal effects of the Enclosure steel members. The wind speed and member sizes have been studied in relation to the required time to reach a defined temperature inside the Enclosure. This is one of the key performance characteristics of the Enclosure that can affect "Dome Seeing" significantly. The experimental data and theoretical predications have been used to identify the areas inside the Enclosure that need to be ventilated. The Enclosure thermal control strategy has been determined and an optimized system has been designed based on the final results.

The Giant Magellan Telescope (GMT) is a planned large terrestrial telescope with a segmented primary mirror with a 24.5 meter overall diameter. Like most terrestrial telescopes, the GMT resides within an enclosure designed to protect the telescope from the elements and to reduce the effects of wind on the optical performance of the telescope. Wind impingement on the telescope causes static deformation and vibration in the telescope structure that affects the alignment and image jitter performance of the telescope. Actively controlled primary mirror segments and a secondary mirror can correct for the static and low frequency portions of the wind effects, but typically the actuators do not have the bandwidth to address higher frequency components of the wind environment. Preliminary analyses on the GMT indicate that the image jitter associated with wind effects meets budgeted allowances but without much margin. Preliminary models show that the bulk of the residual jitter arises from excitation of a small number of modes in the 9 to 12 Hz range. Therefore, as a risk mitigation effort to increase the margin on the wind induced jitter, passive and active vibration mitigation approaches have been examined for the GMT, which will be the focus of this paper. Using a finite element model of the GMT along with wind loading load cases, several passive and active vibration mitigation approaches were analyzed. These approaches include passive approaches such as tuned mass dampers targeting the worst offending modes, and constrained layer damping targeting all of the modes within the troublesome frequency range. Active approaches evaluated include two active damping approaches, one using several reaction mass actuators and the other using active strut type actuators. The results of the study show that although all approaches are successful in reducing the jitter, the active damping approach using reaction mass actuators offers the lightest weight, least implementation impact, and most adaptability of any of the approaches.

The Next Generation Canada-France-Hawaii Telescope is a dedicated, 10m aperture, wide-field, fiber-fed multiobject spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit of Mauna Kea. The Next Generation Canada-France-Hawaii Telescope baseline concept assumes the new facility is built on the existing Canada-France-Hawaii Telescope telescope pier and enclosure pier and occupies the same three dimensional exterior “footprint”. Three technical studies have been planned to examine the validity of these assumptions. The technical studies are executed in series as they represent technical decision points in a logical sequence. The three technical studies in succession are: 1. Telescope Pier Study – Load Capacity and Structural Interface, 2. Enclosure Fixed Base Study – Telescope and Enclosure Configuration and Load Capacity and 3. Aero- Thermal Study – Dome Thermal Seeing and Air Flow Attenuation over the Enclosure Aperture Opening. The paper outlines the baseline facility (telescope, spectrograph and enclosure) concept and the status of these studies, and discusses the proposed telescope and enclosure configuration in terms of the redevelopment assumptions. A consolidated feasibility study report will be submitted to the CFHT Board and Science Advisory Committee in the Fall of 2012, with first light for the facility aiming to be in the early 2020s.

The Astronomical Corporation of New York has commissioned a study of a 12-meter class telescope to be developed by a group of NY universities. The telescope concept builds on the basic principles established by the Keck telescopes; segmented primary mirror, Ritchey Chretien Nasmyth instrument layout, and light weight structures. New, lightweight, and low cost approaches are proposed for the primary mirror architecture, dome structure and mechanisms, telescope mount approach, and adaptive optics. Work on the design is supported by several NY based corporations and universities. The design offers a substantially larger aperture than any existing Visible/IR wavelength telescope at historically low cost. The concept employs an adaptive secondary mirror and laser guide star adaptive optics. Two First Light instruments are proposed; A High resolution near infrared spectrograph and a near infrared Integral field spectrograph/imager.

We review off-axis telescope concepts that use unobstructed pupils. Built and prospective telescopes for ground and space astronomy will be presented and discussed. Such concepts offer great advantages in terms of emissivity, throughput, diffraction- limited energy concentration and higher dynamic range. The coronagraphic performance of off-axis telescopes will enable instruments, which are starving for higher dynamic range, for example, those devoted to faint companion detection and solar studies. Smaller telescopes like SOLAR-C (IfA/Haleakala Observatory), and the New Solar Telescope (NST/NJIT/ Big Bear Observatory) are operational and are test beds for the Advanced Technology Solar Telescope (ATST Project) for which site construction is beginning on Haleakala.

SOFIA, the Stratospheric Observatory for Infrared Astronomy, is an airborne observatory with a 2.7-m telescope that is under development by NASA and the German Aerospace Center DLR. From late 2010 and through the end of 2011, SOFIA conducted a series of science demonstration flights, Early Science, using FORCAST (the Faint Object InfraRed Camera for the SOFIA Telescope), HIPO (the High-speed Imaging Photometer for Occultations), and GREAT (the German REceiver for Astronomy at Terahertz frequencies). Flying at altitudes as high as 13.7 km (45,000 ft), SOFIA operates above more than 99.8% of the water vapor in the Earth’s atmosphere, opening up most of the far-infrared and sub-millimeter parts of the spectrum. During Early Science, 30 science missions were flown with results in solar system astronomy, star formation, the interstellar medium, the Galactic Center, and extragalactic studies. Many of these investigations were conducted by the first group of SOFIA General Investigators, demonstrating the operation of SOFIA as a facility for the astronomical community. This paper presents some recent highlights from Early Science.

The NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA) employs a 2.5-meter reflector telescope in a Boeing 747SP. The telescope is housed in an open cavity and is subjected to aeroacoustic and inertial disturbances in flight. To meet pointing requirements, SOFIA must achieve a pointing stability of approximately 0.5 arcseconds RMS. An active damping control system is being developed for SOFIA to reduce image jitter and image degradation due to resonance of the telescope assembly. Our paper discusses the history of the active damping design for SOFIA, from early concepts to the current implementation which has recently completed a ground and flight testing for proof-of-concept. We describe some milestones in the analysis and testing of the telescope assembly which guided the development of the vibration control system. The control synthesis approach and current implementation of the active damping control system is presented. Finally, we summarize the performance observed in early flight tests and the steps that are currently foreseen to completing the development of this system.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a 2.5 m reflecting telescope housed in an open cavity on board of a Boeing 747SP. During observations, the cavity is exposed to transonic flow conditions. The oncoming boundary layer evolves into a free shear layer being responsible for optical aberrations and for aerodynamic and aeroacoustic disturbances within the cavity. While the aero-acoustical excitation of an airborne telescope can be minimized by using passive flow control devices, the aero-optical properties of the flow are difficult to improve. Hence it is important to know how much the image seen through the SOFIA telescope is perturbed by so called seeing effects. Prior to the SOFIA science fights Computational Fluid Dynamics (CFD) simulations using URANS and DES methods were carried out to determine the flow field within and above the cavity and hence in the optical path in order to provide an assessment of the aero-optical properties under baseline conditions. In addition and for validation purposes, out of focus images have been taken during flight with a Super Fast Diagnostic Camera (SFDC). Depending on the binning factor and the sub-array size, the SFDC is able to take and to read out images at very high frame rates. The paper explains the numerical approach based on CFD to evaluate the aero-optical properties of SOFIA. The CFD data is then compared to the high speed images taken by the SFDC during flight.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently demonstrated its scientific capabilities in a first series of astronomical observing flights. In parallel, special measurements and engineering flights were conducted aiming at the characterization and the commissioning of the telescope and the complete airborne observatory. To support the characterization measurements, two commercial Andor iXon EM-CCD cameras have been used, a DU-888 dubbed Fast Diagnostic Camera (FDC) running at frame rates up to about 400 fps, and a DU-860 as a Super Fast Diagnostic Camera (SFDC) providing 2000 fps. Both cameras have been mounted to the telescope’s Focal Plane Imager (FPI) flange in lieu of the standard FPI tracking camera. Their fast image sequences have been used to analyze and to improve the telescope’s pointing stability, especially to help tuning active mass dampers that suppress eigenfrequencies in the telescope system, to characterize and to optimize the chopping secondary mirror and to investigate the structure and behavior of the shear layer that forms over the open telescope cavity in flight. In June 2011, a collaboration between the HIPO science instrument team, the MIT’s stellar occultation group and the FDC team, led to the first SOFIA observation of a stellar occultation by the dwarf planet Pluto over the Pacific.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently concluded a set of engineering flights for Observatory performance evaluation. These in-flight opportunities have been viewed as a first comprehensive assessment of the Observatory's performance and will be used to address the development activity that is planned for 2012, as well as to identify additional Observatory upgrades. A series of 8 SOFIA Characterization And Integration flights have been conducted from June to December 2011. The HIPO science instrument in conjunction with the DSI Super Fast Diagnostic Camera (SFDC) have been used to evaluate pointing stability, including the image motion due to rigid-body and flexible-body telescope modes as well as possible aero-optical image motion. We report on recent improvements in pointing stability by using an Active Mass Damper system installed on Telescope Assembly. Measurements and characterization of the shear layer and cavity seeing, as well as image quality evaluation as a function of wavelength have been performed using the HIPO+FLITECAM Science Instrument conguration (FLIPO). A number of additional tests and measurements have targeted basic Observatory capabilities and requirements including, but not limited to, pointing accuracy, chopper evaluation and imager sensitivity. This paper reports on the data collected during these flights and presents current SOFIA Observatory performance and characterization.

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) is a suborbital mapping experiment designed to study the role played by magnetic fields in the star formation process. BLASTPol uses a total power instrument and an achromatic half-wave plate to modulate the polarization signal. During its first flight from Antarctica in December 2010, BLASTPol made degree scale maps of linearly polarized dust emission from molecular clouds in three wavebands centered at 250, 350, and 500 μm. This unprecedented dataset in terms of sky coverage, with sub-arcminute resolution, allows BLASTPol to trace magnetic fields in star-forming regions at scales ranging from cores to entire molecular cloud complexes. A second long-duration flight is scheduled for December 2012.

The Cherenkov Telescope Array (CTA) is designed to make a major improvement in the sensitivity of ground based VHE (Very High Energy, defined as > 20GeV to 100s of TeV) gamma-ray telescopes. Not only will the differential-flux sensitivity be an order of magnitude better than those of the currently operating Cherenkov telescopes, but there will also be significant improvements in the energy, spectral and angular resolution. Delivering these features cost-effectively requires several telescope sizes and designs - a few large size telescopes (23m diameter) are designed for the lowest energies, a large number of small size telescopes (4-7m diameter) to increase the overall collection area which helps at the highest energies and a number of Medium Size Telescopes (MST, 9.5m or 12m diameter, depending on the mirror design) to provide the greatest sensitivity at ∼ 1 TeV. To provide complete sky coverage, CTA will have both a Northern Hemisphere and a Southern Hemisphere site. A prototype for an MST design (currently under development) will be build in Berlin by 2012. This MST prototype has a modified Davies-Cotton design with a tessellated mirror, with individual facets of ∼ 1.2m in diameter. The facets are three-point mounted on the optical support structure, having two powered actuators for alignment adjustments. In addition a number of CCD cameras will be mounted at various positions on the dis and will be used for calibration. Here we present the various optical calibration tasks - optimization of the optical point-spread-function (PSF) and the pointing of this MST prototype, along with initial results.

The Cherenkov Telescope Array (CTA) is a ground-based observatory for very high-energy (10 GeV to 100 TeV) gamma rays, planned for operation starting in 2018. It will be an array of dozens of optical telescopes, known as Atmospheric Cherenkov Telescopes (ACTs), of 8 m to 24 m diameter, deployed over an area of more than 1 square km, to detect flashes of Cherenkov light from showers initiated in the Earth's atmosphere by gamma rays. CTA will have improved angular resolution, a wider energy range, larger fields of view and an order of magnitude improvement in sensitivity over current ACT arrays such as H.E.S.S., MAGIC and VERITAS. Several institutions have proposed a research and development program to eventually contribute 36 medium-sized telescopes (9 m to 12 m diameter) to CTA to enhance and optimize its science performance. The program aims to construct a prototype of an innovative, Schwarzschild-Couder telescope (SCT) design that will allow much smaller and less expensive cameras and much larger fields of view than conventional Davies-Cotton designs, and will also include design and testing of camera electronics for the necessary advances in performance, reliability and cost. We report on the progress of the mid-sized SCT development program.

Lowell Observatory's Discovery Channel Telescope is a 4.3m telescope designed for optical and near infrared astronomical observation. At first light, the telescope will have a cube capable of carrying five instruments and the wave front sensing and guider system at the f/6.1 RC focus. The corrected RC focus field of view is 30’ in diameter. Nasmyth and prime focus can be instrumented subsequently. Early commissioning work with the installed primary mirror and its support system started out using one of the wave front sensing probes mounted at prime focus, and has continued at RC with the recent installation of the secondary mirror. We will report on the on-sky pointing and tracking performance of the telescope, initial assessment of the functionality of the active optics support system, and tests of the early image quality of the telescope and optics. We will also describe the suite of first light instruments, and early science operations.

The Large Binocular Telescope (LBT) Observatory is a collaboration between institutions in Arizona, Germany, Italy, Indiana, Minnesota, Ohio and Virginia. The telescope on Mt. Graham in southeastern Arizona uses two 8.4-meter diameter borosilicate honeycomb primary mirrors mounted side-by-side to produce a collecting area equivalent to an 11.8-meter circular aperture. A unique feature of LBT is that the light from the two primary mirrors can be combined to produce phased-array imaging of an extended field. This coherent imaging along with adaptive optics gives the telescope the diffraction-limited resolution of a 22.65-meter telescope. The first on-sky phasing of the two telescopes in the mid-infrared occurred in October 2010 with the LBTI instrument in Fizeau mode. The telescope control system has been upgraded to allow binocular (2-sided) observations with pairs of instruments. The prime focus cameras (LBC) routinely operate in this mode. Improved collimation and pointing models have been deployed to keep both sides collimated and pointed at the same target. The control system has also been upgraded to allow observations of solar system objects at non-sidereal tracking rates. Science observations are scheduled for 60% of the nights including a significant fraction of adaptive optics imaging with the first adaptive secondary mirror and the FLAO system with natural guide stars. MODS1, a nearUV-optical spectrometer, has been added to the suite of science instruments along with LBC (visible imagers) and LUCI1 (near infrared spectrometer). LMIRcam (2-5 microns) and PISCES (1-2.5 microns) have been used for adaptive optics imaging. The remaining nights are scheduled for telescope and instrument commissioning activities as new instruments arrive. The second of the two F/15 adaptive secondary mirrors has been installed on the telescope in Fall 2011 and has been commissioned on-sky in Spring 2012.

Due to the exposed location of the Wendelstein observatory on the steep summit of mount Wendelstein no road exists to transport telescope components and heavy equipment to the observatory in order to install the new 2m Fraunhofer Telescope Wendelstein (FTW) in its new dome. A two step installation concept was therefore followed to mitigate any risks that essential hardware would not work once installed on the mountain. This paper reports on the telescope factory assembly and tests, including on-sky tests, which were performed in early summer 2011 at the factory site to make sure, that the telescope and all essential subsystems are working properly before the telescope would be installed on the mountain. The telescope was disassembled again to be transported to the mountain in summer. Lifting of all structural subsystems and the optics up to the mountain observatory with the help of a heavy lift helicopter will be presented in detail, also looking at specific design drivers, logistic aspects and special tools for installation of the telescope and its mirrors in its new dome. Handling and transport concept for the M1 mirror installation, which also will have to be used when the mirror is disassembled for recoating, are presented. Up to end of 2011 the telescope installation and pre-alignment could be completed including first on-sky tests. The system will undergo a detailed performance test campaign in the first halve of 2012. Current performance results of these commissioning activities will be reported.

The VLT Survey Telescope (VST) has started the scientific operations on the ESO Paranal observatory after a successful commissioning period. It is currently the largest telescope in the world specially designed for surveying the sky in visible light. The VST is dedicated to survey programmes, supporting the VLT with wide-angle imaging by detecting and pre-characterising sources, which the VLT Unit Telescopes can then observe further.

Commissioning of a telescope facility such as the Large Binocular Telescope presents us with unprecedented challenges. The logistical and managerial balance act of scheduling commissioning of telescope, adaptive optics and twelve focal stations with subsequent commissioning of the instruments that populate the focal stations, while still providing for adequate science opportunity with already operational instruments is an equation that is problematic to solve in a way that meets the interests of all stakeholders. This paper presents strategies and priorities applied at the LBTO, and status of telescope commissioning programs. We provide a summary of telescope commissioning results, including a discussion about specific efforts to improve performance of the LBT.

The Discovery Channel Telescope (DCT) is a 4.3-meter telescope with a thin meniscus primary mirror (M1) and a honeycomb secondary mirror (M2). The optical design is an f/6.1 Ritchey-Chrétien (RC) with an unvignetted 0.5° Field of View (FoV) at the Cassegrain focus. We describe the design, implementation and performance of the DCT active optics system (AOS). The DCT AOS maintains collimation and controls the figure of the mirror to provide seeing-limited images across the focal plane. To minimize observing overhead, rapid settling times are achieved using a combination of feed-forward and low-bandwidth feedback control using a wavefront sensing system. In 2011, we mounted a Shack-Hartmann wavefront sensor at the prime focus of M1, the Prime Focus Test Assembly (PFTA), to test the AOS with the wavefront sensor, and the feedback loop. The incoming wavefront is decomposed using Zernike polynomials, and the mirror figure is corrected with a set of bending modes. Components of the system that we tested and tuned included the Zernike to Bending Mode transformations. We also started open-loop feed-forward coefficients determination. In early 2012, the PFTA was replaced by M2, and the wavefront sensor moved to its normal location on the Cassegrain instrument assembly. We present early open loop wavefront test results with the full optical system and instrument cube, along with refinements to the overall control loop operating at RC Cassegrain focus.

During the last year a modified baseline design for the E-ELT has been developed. The aim of this revision was both to achieve a significant cost saving and to reduce risk on major items. The primary mirror diameter was slightly reduced to 39 m and the total height of the telescope also decreased accordingly. This paper describes the work performed by ESO and a variety of contractors to review the EELT design to match the modified baseline. Detailed design and construction planning, as well as detailed cost estimates were updated for the 39-metre baseline design. In June 2011, ESO Council formally endorsed this modified design as the E-ELT revised baseline. The design drivers and balancing cost factors will be described along with the risk reduction measures taken during this phase. This will culminate in the design which has been agreed as being ready to move forward to construction once approval from ESO Council has been achieved.

The Thirty Meter Telescope (TMT) is a public-private-international partnership to build an extremely large optical-infrared telescope on the summit of Mauna Kea on the island of Hawai'i. This paper summarizes the design and predicted performance of TMT, and provides updates on the status of the development and prototype testing activities. TMT is currently in its preconstruction phase. The roles of the partner institutions for developing and delivering observatory subsystems are now well defined, the design work is maturing and plans for construction are in place. Current plans are for start of construction in April 2014, with first light including all 492 segments installed by the end of 2021.

The Giant Magellan Telescope (GMT) is a 25-meter optical/infrared extremely large telescope that is being built by an international consortium of universities and research institutions. It will be located at the Las Campanas Observatory, Chile. The GMT primary mirror consists of seven 8.4-m borosilicate honeycomb mirror segments made at the Steward Observatory Mirror Lab (SOML). Six identical off-axis segments and one on-axis segment are arranged on a single nearly-paraboloidal parent surface having an overall focal ratio of f/0.7. The fabrication, testing and verification procedures required to produce the closely-matched off-axis mirror segments were developed during the production of the first mirror. Production of the second and third off-axis segments is underway. GMT incorporates a seven-segment Gregorian adaptive secondary to implement three modes of adaptive-optics operation: natural-guide star AO, laser-tomography AO, and ground-layer AO. A wide-field corrector/ADC is available for use in seeing-limited mode over a 20-arcmin diameter field of view. Up to seven instruments can be mounted simultaneously on the telescope in a large Gregorian Instrument Rotator. Conceptual design studies were completed for six AO and seeing-limited instruments, plus a multi-object fiber feed, and a roadmap for phased deployment of the GMT instrument suite is being developed. The partner institutions have made firm commitments for approximately 45% of the funds required to build the telescope. Project Office efforts are currently focused on advancing the telescope and enclosure design in preparation for subsystem- and system-level preliminary design reviews which are scheduled to be completed in the first half of 2013.

The modifications to the European Extremely Large Telescope (E-ELT) baseline design were accompanied by an evaluation of their impact on science. We will present the conclusions of this evaluation. The Design Reference Mission served as the benchmark for the evaluation. None of the modifications critically affect the Science Case. In particular, the full instrumentation suite can still be implemented allowing for the full foreseen suite of science cases. The largest impact is induced by the reduced diameter. For a large fraction of the science cases this can be offset by increasing the exposure times by ~20% to 34%. Where spatial resolution is the limiting factor, the limits have to be reduced by 9%. The exoplanet case deserves a special mention: two of the three components of this case (detection of Earth twins by the radial velocity method, and characterisation of the atmospheres of transiting planets) are unaffected; for the third component (direct imaging of Earth-like planets) the same results as for the original baseline can be achieved, but only at 20% smaller distances. Overall, all of the major science cases of the E-ELT can essentially be maintained.

We report the first measurements of 225 GHz atmospheric opacity at Summit Camp (Latitude 72°.57 N; Longitude 38°.46 W; Altitude 3250 m) in Greenland and the Polar Environment Atmospheric Research Laboratory (PEARL: Latitude 80°.05 N; Longitude 86°.42 W; Altitude 600 m) in Northern Canada with a tipping radiometer. Summit Camp and PEARL are research stations mostly interested in meteorology and geophysics, and they are potentially excellent sites for astronomical observations at sub-millimeter wavelength. We purchased a tipping radiometer from Radiometer Physics GmbH. After a test run at the summit of Mauna Kea, Hawaii, the radiometer was deployed to PEARL in February 2011, and relocated to Summit Camp in August 2011. The atmospheric opacity has been monitored from February 14th to May 10th, 2011 at PEARL and since August 2011 at Summit Camp. The median values of the measured opacity at PEARL ranged from 0.11 in February to 0.19 in May; Summit Camp varied in the range from 0.04 to 0.18 between August 2011 and May 2012. Summit Camp in Greenland is expected to be an excellent site for sub-millimeter and Terahertz astronomy, and we plan to set up there a 12-m telescope for VLBI and single-dish observations.

The site survey in western China has been carried out since 2003. Remote studies and local surveys are performed, and Oma site, Ali area in southwest Tibet, has been selected in 2005 to make site testing measurements. The monitoring results show that Ali area can be the best choice for astronomical observations over the East Asian regions. A new site in Ali has been identified and begun construction in 2010 for small telescopes and detailed site characterization. This paper reviews the long term site survey, presents site characteristics in Tibet, and introduces current status of the new Ali observatory.

Changing atmospheric transmission accounts for the largest systematic errors limiting photometric measurement precision and accuracy for ground-based telescopes. While considerable resources have been devoted to correcting the effects of the atmosphere on image resolution, the effects on precision photometry have largely been ignored. To correct for the transmission of the atmosphere requires direct measurements of the wavelength-dependent transmission in the same direction and time that the supported photometric telescope is acquiring its data. We describe a multi-wavelength lidar, the Facility Lidar for Astronomical Measurement of Extinction (FLAME) that observes the stable upper stratosphere, and the Astronomical Extinction Spectrophotometer (AESoP), a spectrophotometer that creates and maintains NIST absolute standard stars. The combination of these two instruments enables high photometric precision of both the stellar spectra and atmospheric transmission. The throughput of both FLAME and AESoP are calibrated to NIST radiometric standards. This inexpensive and replicable instrument suite provides the lidar-determined monochromatic transmission of Earth’s atmosphere at visible and near-infrared wavelengths to better than 0.25% per airmass and the wavelength-dependent transparency to better than 1% uncertainty per minute. These atmospheric data are merged to create a metadata stream that allows throughput corrections from data acquired at the time of the scientific observations to be applied to broadband and spectrophotometric scientific data. This new technique replaces the classical use of nightly mean atmospheric extinction coefficients, which invoke a stationary and plane-parallel atmosphere and ultimately limit ground-based all-sky photometry to 1% - 2% precision.

In the spring of 2010, the Academia Sinica Institute of Astronomy and Astrophysics, and the Smithsonian Astrophysical Observatory, acquired the ALMA North America prototype antenna – a state-of-the-art 12-m diameter dish designed for submillimeter astronomy. Together with the MIT-Haystack Observatory and the National Radio Astronomy Observatory, the plan is to retrofit this antenna for cold-weather operation and equip it with a suite of instruments designed for a variety of scientific experiments and observations. The primary scientific goal is to image the shadow of the Super-Massive Black Hole in M87 in order to test Einstein’s theory of relativity under extreme gravity. This requires the highest angular resolution, which can only be achieved by linking this antenna with others already in place to form a telescope almost the size of the Earth. We are therefore developing plans to install this antenna at the peak of the Greenland ice-sheet. This location will produce an equivalent North-South separation of almost 9,000 km when linked to the ALMA telescope in Northern Chile, and an East-West separation of about 6,000 km when linked to SAO and ASIAA’s Submillimeter Array on Mauna Kea, Hawaii, and will provide an angular resolution almost 1000 times higher than that of the most powerful optical telescopes. Given the quality of the atmosphere at the proposed telescope location, we also plan to make observations in the atmospheric windows at 1.3 and 1.5 THz. We will present plans to retrofit the telescope for cold-weather operation, and discuss potential instrumentation and projected time-line.

The preliminary site testing carried out since the beginning of 2008 shows the Antarctic Dome A is very likely to be the best astronomical site on earth even better than Dome C and suitable for observations ranging from optical wavelength to infrared and sub-millimeter. After the Chinese Small Telescope Array (CSTAR) which is composed of four small fixed telescopes with diameter of 145mm and mounted on Dome A in 2008 for site testing and variable star monitor, three Antarctic Survey Telescopes (AST3) were proposed for observations of supernovas and extrasolar planets searching. AST3 is composed of 3 large field of view catadioptric telescopes with 500mm entrance diameter and G, R, I filter for each. The telescopes can point and track autonomously along with a light and foldable dome to keep the snow and icing build up. A precise auto-focusing mechanism is designed to make the telescope work at the right focus under large temperature difference. The control and tracking components and assembly were successfully tested at from normal temperature down to -80 Celsius degree. Testing observations of the first AST3 showed it can deliver good and uniform images over the field of 8 square degrees. The first telescope was successfully mounted on Dome A in Jan. 2012 and the automatic observations were started from Mar. 2012.

Mountains along the northwestern coast of Ellesmere Island, Canada, possess the highest peaks nearest the Pole. This geography, combined with an atmospheric thermal inversion restricted to below ~1000 m during much of the long arctic night, provides excellent opportunities for uninterrupted cloud-free astronomy - provided the challenges of these incredibly remote locations can be overcome. We present a miniaturized robotic observatory for deployment on a High Arctic mountaintop. This system tested the operability of precise optical instruments during winter, and the logistics of installation and maintenance during summer. It is called Ukpik after the Inuktitut name for the snowy owl, and was deployed at two sites accessible only by helicopter, each north of 82 degrees latitude; one on rock at 1100 m elevation and another on a glacier at 1600 m. The instrument suite included at first an all-sky-viewing camera, with the later addition of a small telescope to monitor Polaris, both protected by a retractable weather-proof enclosure. Expanding this to include a narrow-field drift-scanning camera for studying extra-solar planet transits was also investigated, but not implemented. An unique restriction was that all had to be run on batteries recharged primarily by a wind turbine. Supplementary power came from a methanol fuel-cell electrical generator. Communications were via the Iridium satellite network. The system design, and lessons learned from three years of operation are discussed, along with prospects for time-domain astronomy from isolated, high-elevation polar mountaintops.

The Gattini South Pole UV experiment (Gattini SPUV) was deployed to the South Pole dark sector in February 2010 and has recently completed a highly successful first season of winter time observations. The experiment has, for the first time ever, measured and categorized the optical night sky brightness at the very blue wavelengths. The experiment consists of a remotely operated 6” aperture custom designed telescope. The telescope feeds a blue sensitive imager with 4 degree field of view that contains a bank of 3 filters: SDSS g’, Bessel U and a custom “super U” filter specifically designed to probe the sky emission at wavelengths approaching the atmospheric cut-off. The filters are continually cycled with exposure times ranging from 30 to 300 seconds throughout the winter period. The telescope, in addition, feeds a 2 degree long slit VPH grating spectrograph with R~1000. The bandwidth is 350-450nm. The spectra are recorded simultaneously with the imager exposures. The experiment is designed for low temperature Antarctic operation and resides on the roof of the MAPO building in the South Pole Antarctic sector. The primary science goals are to categorize the Antarctic winter-time sky background at the very bluest of wavelengths as a pathfinder for the Antarctic Cosmic Web Imager. We present a technical overview of the experiment and results from the first winter season.

PLATO-R is an autonomous, robotic observatory that can be deployed anywhere on the Antarctic plateau by Twin Otter aircraft. It provides heat, data acquisition, communications, and up to 1kW of electric power to support astronomical and other experiments throughout the year. PLATO-R was deployed in 2012 January to Ridge A, believed to be the site with the lowest precipitable water vapour (and hence the best atmospheric transmission at terahertz frequencies) on earth.^1-4 PLATO-R improves upon previous PLATO designs that were built into ten-foot shipping containers by being much smaller and lighter, allowing it to be field-deployable within 2-3 days by a crew of four.

As part of the image quality (IQ) assessment and improvement initiative being carried out at the 3.6m Canada France Hawaii Telescope (CFHT) on Mauna Kea, Hawaii, our objective in the work reported here is to obtain a systematic assay of thermal sources within the dome and in the summit environment around the observatory, and therefore mitigate their contributions to convective instability leading to 'dome seeing'. Toward this, we undertook a nighttime overflight to capture thermal images with a calibrated infrared camera of the outer structures of CFHT and the neighboring observatories on the summit ridge, as well as of a significant area of the surrounding terrain. The same thermal camera was then used to image heat sources within the dome. Using a convective heat transfer model, all these measured surface temperatures were converted to heat fluxes, and thus used to build a thermal assay of the dome. In addition, using button type temperature loggers, we simultaneously recorded the nighttime dome skin temperatures of CFHT and two other observatories over a weeklong period to evaluate nighttime supercooling of the dome skin due to radiation to the cold night sky. As a complementary goal we compared the efficacy of different paints and coatings used in observatories to minimize this effect. Though similar studies have been carried out at other observatories, the results are rarely available in published literature. Therefore, here we explain our methodologies, along with a detailed discussion of our results and inferences to serve as a useful resource to the larger observing community.

Devasthal, located in the Kumaun region of Himalayas is emerging as one of the best optical astronomy site in the continent. The minimum recorded ground level atmospheric seeing at the site is 0.006 with median value at 1.001. Currently, a 1.3-m fast (f/4) wide field-of-view (660) optical telescope is operating at the site. In near future, a 4-m liquid mirror telescope in collaboration with Belgium and Canada, and a 3.6-m optical telescope in collaboration with Belgium are expected to be installed in 2013. The telescopes will be operated by Aryabhatta Research Institute of Observational Sciences. The first instruments on the 3.6-m telescope will be in-house designed and assembled faint object spectrograph and camera. The second generation instruments will be including a large field-of-view optical imager, high resolution optical spectrograph, integral field unit and an optical near-infrared spectrograph. The 1.3-m telescope is primarily used for wide field photometry imaging while the liquid mirror telescope will see a time bound operation to image half a degree wide strip in the galactic plane. There will be an aluminizing plant at the site to coat mirrors of sizes up to 3.7 m. The Devasthal Observatory and its geographical importance in between major astronomical observatories makes it important for time critical observations requiring continuous monitoring of variable and transient objects from ground based observatories. The site characteristics, its expansions plans and first results from the existing telescope are presented.

The Emirates Institute for Advanced Science and Technology (EIAST) investigated the possibility to setup an astronomical research and outreach center within the United Arab Emirates. The main goals of such a new institution are to raise interest in space research and to ultimately develop a significant research community within the UAE. Such an astronomy center will also require appropriate observatory facilities. In this paper current concepts of such a possible national UAE astronomy observatory will be outlined, and the findings of an initial survey for suitable locations to host the telescopic facilities within the UAE are presented.

AMOS SA has been awarded of the contract for the design, manufacturing, assembly, tests and on site installation (Devasthal, Nainital in central Himalayan region) of the 3.6 m Indo-Belgian Devasthal Optical Telescope (IDOT). The telescope has Ritchey-Chrétien optical configuration with one axial and two side Cassegrain ports. The meniscus primary mirror is active and it is supported by pneumatic actuators. The azimuth axis system is equipped with hydrostatic bearing. The telescope was completely assembled and tested in AMOS workshop. This step is completed and successful. The telescope is now ready for shipment to Nainital. This paper describes the telescope and summarizes the test results performed at AMOS to demonstrate that the telescope satisfies the main system requirements.

Over the past few years, Sagem REOSC has designed, manufactured and tested a 2.5m ALT/AZ telescope and its complete observatory. The next stage - integration - should occur in 2012. The aim of this paper is to develop the different stages of the project from technical and management's point of view. The telescope is a 2.5m-class telescope with an aperture of F/8. It is composed of a 2.5m primary mirror made of Zerodur©, a silica secondary mirror and a rotating tertiary mirror that allows pointing at Nasmyth foci. In addition, a wide field corrector can be adapted either at Cassegrain focus or at Nasmyth focus. Results achieved on the realization of such optics will be presented. An emphasis on the concurrent engineering and the problem solving approach will also be presented.

The E-ELT is a project led by the European Southern Observatory (ESO) for a 40-m class optical, near- and midinfrared, ground-based telescope. When it will enter into operation, the E-ELT will be the largest and most powerful optical telescope ever built. It will not only offer unrivalled light collecting power, but also exceedingly sharp images, thanks to its ability to compensate for the adverse effect of atmospheric turbulence on image sharpness. The basic optical solution for the EELT is a folded three-mirror anastigmat, using a 39-m segmented primary mirror (M1), a 4-m convex secondary mirror (M2), and a 4-m concave tertiary mirror (M3), all active. Folding is provided by two additional flat mirrors sending the beams to either Nasmyth foci along the elevation axis of the telescope. The folding arrangement (flat M4 and M5 mirrors) is conceived to provide conveniently located flat surfaces for an adaptive shell (M4) and field stabilization (M5). That paper provides an overview of the specifications, design, and expected performance of the E-ELT optical systems.

During the advanced design phase of the European Extremely Large Telescope (E-ELT) several critical components have been prototyped. During the last year some of them have been tested in dedicated test stands. In particular, a representative section of the E-ELT primary mirror has been assembled with 2 active and 2 passive segments. This test stand is equipped with complete prototype segment subunits, i.e. including support mechanisms, glass segments, edge sensors, position actuators as well as additional metrology for monitoring. The purpose is to test various procedures such as calibration, alignment and handling and to study control strategies. In addition the achievable component and subsystem performances are evaluated, and interface issues are identified. In this paper an overview of the activities related to the E-ELT M1 Test Facility will be given. Experiences and test results are presented.

The fifth mirror unit (M5) of the E-ELT is a field stabilization unit responsible to correct for the dynamical tip and tilt caused mainly due to the wind load on the telescope. The unit is composed of: i) an electromechanical subunit, and ii) an elliptical mirror with a size of approximately 2.4 by 3-m. The M5 unit has been designed and prototyped using a three point support for the mirror actuated by piezo actuators without the need of a counter weight system. To be able to meet the requirements of the telescope, i.e. sufficient wavefront rejection capability, the unit shall exhibit a sufficient bandwidth for tip/tilt reference commands. In the presence of the low damped mechanical resonant modes, such a bandwidth can be guaranteed thanks to an active damping loop. In this paper, different active damping strategies for the M5 unit are presented. The efficiency of the approaches are analyzed using a detailed model of the unit. On a scale-one prototype active damping was implemented and the efficiency was demonstrated.

The Giant Magellan Telescope (GMT) will be a 25m class telescope currently in the design and development phase. The GMT will be a Gregorian telescope and equipped with a fast-steering secondary mirror (FSM). This secondary mirror is 3.2 m in diameter and built as seven 1.1 m diameter circular segments conjugated 1:1 to the seven 8.4m segments of the primary. The prototype of FSM (FSMP) development effort is led by the Korea Astronomy and Space Science Institute (KASI) with several collaborators in Korea, and the National Optical Astronomy Observatory (NOAO) in USA. The FSM has a tip-tilt feature to compensate image motions from the telescope structure jitters and the wind buffeting. For its dynamic performance, each of the FSM segments is designed in a lightweight mirror. Support system of the lightweight mirror consists of three axial actuators, one lateral support at the center, and a vacuum system. A parametric design study to optimize the FSM mirror configuration was performed. In this trade study, the optical image qualities and structure functions for the axial and lateral gravity print-through cases, thermal gradient effects, and dynamic performances will be discussed.

Stress induced cracks have developed in the Zerodur glass at bonded supports for the primary mirror segments of the W.M. Keck Observatory telescopes. This has been a slow process that has advanced over the 20 year life of the telescopes. All mirror segments exhibit cracks to varying degrees. The number and severity of cracks has now reached a stage at which repairs are mandatory. A project is under way to determine the root causes of the cracks, and to develop a repair strategy. New supports and bonding methods are being designed and tested that will replace all of the original supports.

A variety of algorithms utilized in the alignment of segmented telescopes were developed for and implemented on the Keck telescopes in the 1990s. The algorithms associated with the Keck segmented primary mirrors are very similar to those that will be used for the Thirty Meter Telescope (TMT). However, there are alignment or related wavefront measurement tasks associated with the TMT secondary and tertiary mirrors for which the corresponding Keck algorithms either did not exist or are not adequate for TMT. We discuss two particular algorithms associated with the TMT secondary and tertiary mirrors.

The Giant Magellan Telescope (GMT) is a 25.4 m diameter ground-based segmented Gregorian telescope, composed of 7 8.4 meter diameter primary mirror segments, and 7 1 meter diameter adaptive secondary mirror segments. Co-phasing of the integrated optical system will be partially achieved by making real-time measurements of the wavefront of an offaxis guide star. However, slowly varying aberrations due to thermal and gravitational effects, as well as wind buffeting, will make it difficult to maintain alignment using real-time optical measurements alone. Consequently, we are proposing internal metrology systems to maintain the relative alignment of the optical elements. In this paper we describe a differential capacitive edge sensing system to maintain the relative alignment of the adaptive secondary mirror reference bodies. We also propose an interferometric system for sensing of the relative displacements of primary mirror segments.

The Giant Magellan Telescope (GMT) Fast-steering secondary mirror (FSM) is one of the GMT two Gregorian secondary mirrors. The FSM is 3.2 m in diameter and built as seven 1.1 m diameter circular segments conjugated 1:1 to the seven 8.4m segments of the primary. A parametric study and optimization of the FSM mirror blank and central lateral flexure design were performed. For the optimized FSM configuration, the optical image qualities and structure functions for the axial and lateral gravity print-through cases, thermal gradient effects, and dynamic performances will be discussed. This paper reports performance predictions of the optimized FSM. To validate our lateral flexure design concept, mechanical and optical tests were conducted on test mirrors installed with two different lateral flexures.

This paper examines the active optics of future large segmented telescopes from the point of view of dynamic simulation and control. The first part of the paper is devoted to the modelling of the mirror. The model has a moderate size and separates the quasi-static behavior of the mirror (primary response) from the dynamic response (secondary or residual response). The second part of the paper is devoted to control. The control strategy considers explicitly the primary response of the telescope through a singular value controller. The control-structure interaction is addressed with the general robustness theory of multivariable feedback systems, where the secondary response is considered as uncertainty. This approach is very fast and allows extensive parametric studies. The study is illustrated with an example involving 90 segments, 270 inputs, and 654 outputs.

Upon its completion, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) will be the largest single dish radio telescope ever in the world. The construction has been initiated in March 2011 in Guizhou province of China. The whole construction process is expected to be completed in September 2016, with duration of 5.5 years. With an aperture of 500 meters and an illumination aperture of 300 meters, the active reflector is one of the most important parts of FAST. The reflector is composed of a ring beam, a cable net and thousands of panels, tie-down cables, actuators and anchors. For the observation process of source switching and source tracking, the parabola shape of the reflector is achieved by drawing back of the tie-down cables by the actuators. The motion performance and the reliability of the actuators are of great importance to the telescope. In this paper, the motion models of the actuators are analyzed for the observation process of source switching and source tracking. Several design schemes are proposed, including mechanical and hydraulic design. The electric, mechanical and hydraulic characteristics of these designs are discussed. Related experimental studies are performed to investigate the electric and mechanical performances of these actuator prototypes. Based on the analysis and test results, a final type of actuator will be optimally concluded to meet the requirements of the reflector of FAST.

The design, development and manufacturing of a fully automated and cost effective aluminum sputtering unit for the deposition of aluminum on large area telescopic mirrors (maximum diameter of 3600mm) is presented here. The unit employs DC planar magnetron sputtering for the deposition process. A large area glow discharge unit is also designed for the pre-cleaning of the mirrors prior to aluminum coating. A special kinematic support structure with rotation is designed to support heavy mirrors of large area to minimize the deflection of the mirrors during deposition process. A custom designed 'mask' is employed in the magnetron system to improve the thickness uniformity within <±3%. The adhesion, thickness uniformity and reflectivity properties are studied in detail to validate the sputtering plant. Special fixtures have been designed for the system to accommodate smaller mirrors and studies have been conducted for the coatings and reported in the paper. The unit was successfully tested at HHV facility in Bangalore and will be installed at the ARIES Facility, Nainital.

The Australian Square Kilometre Array Pathfinder (ASKAP) will be the fastest cm-wave survey radio-telescope and is under construction on the new Murchison Radio-astronomy Observatory (MRO) in Western Australia. ASKAP consists of 36 12-meter 3-axis antennas, each with a large chequerboard phased array feed (PAF) operating from 0.7 to 1.8 GHz, and digital beamformer preceding the correlator. The PAF has 94 dual-polarization elements (188 receivers) and the beamformer will provide about 36 beams (at 1.4 GHz) to produce a 30 square degree field of view, allowing rapid, deep surveys of the entire visible sky. As well as a large field of view ASKAP has high spectral resolution across the 304 MHz of bandwidth processed at any one time generating a large data-rate (30Gb/sec in to the imaging system) that requires real-time processing of the data. To minimise this processing and maximise the field of view for long observations the antenna incorporates a third axis, which keeps the PAF field of view and sidelobes fixed relative to the sky. This largely eliminates time varying artefact in the data that is processed. The MRO is 315 kilometres north-east of Geraldton, in Western Australia’s Mid West region. The primary infrastructure construction for ASKAP and other telescopes hosted at the Murchison Radio-astronomy Observatory has now been completed by CSIRO, the MRO manager, including installation of the fibre connection from the MRO site to Perth via Geraldton. The radio-quietness of the region is protected by the Mid West Radio Quiet Zone, implemented by the Australian Federal Government, out to a radius of 260km surrounding the MRO.

LOFAR, the Low Frequency Array, is a next-generation radio telescope designed by ASTRON, with antenna stations concentrated in the north of the Netherlands and currently spread into Germany, France, Sweden and the United Kingdom; plans for more LOFAR stations exist in several other countries. Utilizing a novel, phased-array design, LOFAR is optimized for the largely unexplored low frequency range between 30 and 240 MHz. Digital beam-forming techniques make the LOFAR system agile and allow for rapid re-pointing of the telescopes as well as the potential for multiple simultaneous observations. Processing (e.g. cross-correlation) takes place in the LOFAR BlueGene/P supercomputer, and associated post-processing facilities. With its dense core (inner few km) array and long (more than 1000 km) interferometric baselines, LOFAR reaches unparalleled sensitivity and resolution in the low frequency radio regime. The International LOFAR Telescope (ILT) is now issuing its first call for observing projects that will be peer reviewed and selected for observing starting in December. Part of the allocations will be made on the basis of a fully Open Skies policy; there are also reserved fractions assigned by national consortia in return for contributions from their country to the ILT. In this invited talk, the gradually expanding complement of operationally verified observing modes and capabilities are reviewed, and some of the exciting first astronomical results are presented.

The goal of the RAEGE (Red Atlantica Estaciones Geodinamicas Espaciales) project is the establishment of a Spanish-Portuguese network of geodynamical and spatial geodesy stations by the installation and operation of four fundamental geodetic / astronomical stations provided with radio telescopes located at - Yebes, close to Madrid / Spain - Tenerife, Canary Islands / Spain - Santa Maria, Azores Islands / Portugal. VLBI 2010 radiotelescopes are belonging to a new generation of radiotelescopes suitable for high precision geodetical earth observation and measurements, that shall allow to built up a high precision global reference system. The design of the radiotelescopes has been finished by MT Mechatronics in summer 2011 and currently three radiotelescopes are being manufactured. The first one is scheduled for installation in summer 2012 at Yebes Observatory close to Madrid.

The Sardinia Radio Telescope (SRT) Metrology team is planning to install an initial group of devices on the new 64 meters radio-telescope. These devices will be devoted for the realization of the antenna deformation control system: an electronic inclinometer able to monitor the alidade deformations and a Position Sensing Device (PSD) able to map the antenna secondary mirror (M2) displacements and tilts. The inclinometer will be used to map the rail conditions, the azimuthal axis inclination and the thermal effects on the alidade structure. The PSD will be used to measure the secondary mirror displacements induced by the gravity and by the thermal deformations that produce shifts and tilts with respect to its ideal optical alignment. The PSD will be traced by diode laser installed on a mechanically stable position inside the elevation equipment room. The inclinometer has been tested in laboratory with the aim to compare its performances with a reference measurement system. The PSD and the laser have been characterized by a long-term tests to assess their stability and accuracy, thus simulating the open air conditions that will be experienced by the device during its operative life. M2 may move freely in space thanks to a six axis actuator system (hexapod). The PSD measurements are processed by a hexapod kinematic model (HKM) to evaluate the correct actuator elongations, thus closing the control loop. The sensors will be acquired and recorded by a dedicated PC installed in the Alidade equipment room and connected to the sensors via the Ethernet network.

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is currently under construction at a Karst depression in the Guizhou province of China. The active reflector of the telescope is composed of 4395 triangular panels laid on a cable-net structure. The aperture of the spherical surface is 500 meters, with open angle of about 110~120 degrees. Acting as the nodes of the reflector, the joint of these panels are adjusted by 2235 down-tie cables drawn by actuators. The RMS error of the parabola reflector is expected to be 5mm. To form the parabola shape of the reflector, for each of the actuators, a minimal working stroke of 950mm is required, with maximal speed of 1.6mm/s at the load of 50kN. Considering the elastic deformation of the down-tie cable and other factors, a positioning error within 0.25mm is required for the actuators. In this paper, the base formula for the motion of a general actuator at a typical observation time is studied analytically. The results are used to estimate the control error of the actuators and the pointing error of the whole reflector. Based on the designed error budgets, a statistical method is employed to estimate the overall surface error of the parabola reflector. The overall surface error is a comprehensive result of the panel design error, panel fabrication error, thermal deformation error, panel wind load induced error, cable-net error, installation error, measurement and control error etc. The results may be used as a reference in the measurement and control of the active reflector when in operation.

The Sardinia Radio Telescope (SRT) is the largest radio telescope recently built in Europe – a 64m Radio Telescope designed to operate in a wavelength regime down to 1mm. The SRT is designed in a classical Gregorian configuration, allowing access to the primary mirror focus (F1), the Gregorian focus (F2) as well as a further translation to different F3 using a beam waveguide system and an automated change between different F3 receiver positions. The primary mirror M1, 64m in diameter, is composed by 1008 individual panels. The surface can be actively controlled. It’s surface, as well as the one of the 8 m Gregorian subreflector, needed to be adjusted after panel mounting at the Sardinia site. The measurement technique used is photogrammetry. In case of the large scale M1 a dedicated combination of a large scale and a small scale approach was developed to achieve extremely high accuracy on the large scale dimension. The measurement/ alignment efforts were carried out in 2010 and 2011, with a final completion in spring 2012. The results obtained are presented and discussed. The overall alignment approach also included the absolute adjustments of M2 to M1 and the alignments of M3, M4 and M5. M3 is a rotating mirror guiding the RF beam to M4 or M5, depending on the operational scenario. These adjustments are based on Lasertracker measurements and have been carried out in an integrated approach.

The Atacama Large Millimeter Array (ALMA) is under erection in Northern Chile. The array consists of a large number (up to 64) of 12 m diameter antennas and a number of smaller antennas, to be operated on the Chajnantor plateau at 5000 m altitude. The antennas will operate up to 950 GHz so that their mechanical performances, in terms of surface accuracy, pointing precision and dimensional stability, are very tight. The AEM consortium constituted by Thales Alenia Space France, Thales Alenia Space Italy, European Industrial Engineering (EIE GROUP), and MT Mechatronics is assembling and testing the 25 antennas. As of today, the first set of antennas have been delivered to ALMA for science. During the test phase with ESO and ALMA, the European antennas have shown excellent performances ensuring the specification requirements widely. The purpose of this paper is to present the different results obtained during the test campaign: surface accuracy, pointing error, fast motion capability and residual delay. Very important was also the test phases that led to the validation of the FE model showing that the antenna is working with a good margin than predicted at design level thanks also to the assembly and integration techniques.

The ALMA aperture synthesis radio telescope is under construction in northern Chile. This paper presents the organization and process of ALMA System Verification. The purpose of System Verification is to measure the performance of the integrated instrument with respect to the ALMA System Technical Requirements. The System Technical Requirements flow down from the Science Requirements of the telescope and are intended to guide the design of the array and set the standards for technical performance. The process of System Verification will help determine how well the ALMA telescope meets its science goals. Some verification results are discussed.

CCAT will be a 25 m diameter telescope operating in the 2 to 0.2 mm wavelength range. It will be located at an altitude of 5600 m on Cerro Chajnantor in Northern Chile. The telescope will be equipped with wide-field, multi-color cameras for surveys and multi-object spectrometers for spectroscopic follow up. Several innovations have been developed to meet the <0.5 arcsec pointing error and 10 μm surface error requirements while keeping within the modest budget appropriate for radio telescopes.

When making holography measurements on a large telescope, there are many factors that make it difficult to obtain a consistent map. Two of these factors are variations of the satellite and temperature-induced deformations of the reflecting surface. The former requires frequent returns to the center of the map to check the satellite and the latter requires that the map be completed rapidly and at night. While holography mapping has traditionally been performed using point-by-point or raster scanning, these methods involve substantial overhead in the frequent movements back to the center of the map. In performing holography maps of the Large Millimeter Telescope (LMT) for the first light campaign, the observing team proposed a radial scanning approach. This strategy has the advantage that every scan passes through the center of the map. However, such a scan results in a disproportionate amount of telescope time near the center region. To achieve more uniform coverage, the team proposed a velocity profile that is inversely proportional to the distance from the center of the map. Because the velocity profile is defined with respect to position rather than time, this new approach required an extension of the existing parametric scanning capabilities at the LMT. The high axis rates resulting from this velocity profile present additional challenges. This paper describes the implementation and performance results for holography maps that use a radial scan pattern with a position-dependent velocity profile at the LMT. Both theoretical and experimental results are presented.

In signal transmission through optical fiber, cable length delay fluctuation accompanied by chromatic and polarization-mode dispersion affects the coherence of distributed signals. To maintain signal coherence, it is very important to generate very-high-frequency signals with minimum phase noise and transmission loss. In a photonic local signal generation/distribution system with a microwave-photonic signal generator and a real-time microwave-photonic signal phase stabilizer that we developed as an alternative photonic LO system for ALMA (Atacama Large Millimeter/sub-millimeter Array), signals are transmitted in the form of frequency difference between two coherent light waves, effectively maintaining the coherence of distributed reference signals. Through the development of the real-time phase stabilizer, we discovered that the system would be further improved with the introduction of a post-processing scheme phase stabilizer and confirmed its effectiveness by experiments.

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter baseline far-infrared interferometer to fly on a high altitude balloon. Operating at wavelengths of 30-90 microns, BETTII will obtain spatial and spectral information on science targets at angular resolutions down to less than half an arcsecond, a capability unmatched by other far-infrared facilities. This requires attitude control of the gondola at the several arcsecond level, and phase correction of the gondola attitude at a level of less than a tenth of an arcsecond, great challenges for a lightweight balloon-borne system. We have designed a precision attitude determination system to provide gondola attitude knowledge at a level of 2 milliarcseconds at rates up to 100Hz, with accurate absolute attitude determination at the half arcsecond level at rates of up to 10Hz. A multi-stage control system involving rigid body motion and tip-tiltpiston correction provides precision pointing stability to the level required for the far-infrared instrument to perform its spatial/spectral interferometry in an open-loop control. We present key aspects of the design of the attitude determination and control and its development status.

The possibility to open a near-IR window at stratospheric altitude is crucial for a large variety of astronomical issues, from cosmology to the star formation processes. Up to now, one of the main issue is the role of the OH and thermal sky emission that are rising the sky background level when such observations are performed through ground based telescopes. We present the results of our technological activity aimed at affording some critical aspects typical of balloon flights. In particular, the obtained performances of prototype systems for rough and fine tracking will be illustrated. Both these systems constitute a high precision device (≤ 1 arcsec) for pointing and tracking light telescopes on board stratospheric balloons. We give the details concerning the optical and mechanical layout, as well as the detector and the control system. We demonstrate how such devices, when used at the focal plane of enough large telescopes(2-4m, F/10), may be capable to provide diffraction limited images in the near infrared bands. We have also developed a prototypal single channel photometer NISBA (Near Infrared Sky Background at Arctic pole), working in the H band (1.65 μm), able to evaluate, during a high-latitude balloon flight, how OH emission affects the sky background during the arctic night. The laboratory tests and performance on sky are presented and analyzed.

The Stratospheric Observatory for Infrared Astronomy SOFIA started in December 2010 with the first series of science flights, and has successfully completed about 38 science missions until fall 2011. The science instruments flown included HIPO, FORCAST, GREAT and FLITECAM. Beside their scientific results (see related papers in these proceedings) the flights delivered an extensive data base which is now used for the telescope performance characterization and the operational optimization of the telescope in its unique environment. In this progress report we summarize recent achievements of the observatory as well as the status of the telescope and give an update of the SOFIA pointing system completed by intended future pointing optimization activities.

The telescope of the Stratospheric Observatory for Infrared Astronomy (SOFIA) is a Cassegrain design with a convex, hyperbolic secondary mirror. It is 352 mm in diameter, was made from silicon carbide and weighs only 1.9 kg. As this material is brittle, and the secondary mirror is indispensable to observations with SOFIA, a backup with the same mass and moments of inertia was made of aluminium in 2004. This mirror, however, allows diffraction-limited observations only above 20 μm and it produces double peaked images. In this paper we discuss the requirements for a new backup secondary mirror that can be employed also at near-infrared and even visible wavelengths and describe the most important aspects of the manufacturing process. The starting point of our analysis was a high-precision measurement of the surface properties of the existing aluminium secondary mirror, using the NANOMEFOS technique, which was recently developed by TNO in Delft, the Netherlands. With the exact shape of the mirror as input for a Zemax model we could reproduce the results of actual measurements of its optical performance that had been carried out on SOFIA in 2004. Based on these findings we determined then the specifications to be fulfilled by a new backup secondary mirror in order to meet the requirements on improved optical performance. Finally, we discuss the dynamic deformation of the aluminium mirror during chopping motions.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) uses three CCD cameras with different optics for target acquisition and tracking. The Wide Field Imager (WFI with 68 mm optics) and the Fine Field Imager (FFI with 254 mm optics) are mounted on the telescope front ring and are therefore exposed to stratospheric conditions in flight. The Focal Plane Imager (FPI) receives the visible light from the 2.5 meter telescope and is mounted inside the pressurized aircraft cabin at ca. 20°C. It is planned to replace all three imagers' CCD sensors with commercial Andor iXon cameras to significantly increase the sensitivity allowing for tracking on fainter stars. Andor cameras were temporarily mounted on the FPI flange as stand-alone systems to optically measure the telescope's pointing stability and the performance of various telescope sub-systems during engineering flights. Three DU-888 cameras will now be integrated in SOFIA's telescope system, so their image data can be used for target acquisition and tracking. To replace the WFI and FFI, the cameras will also need to be tested under stratospheric conditions, to ensure that they can be operated safely and without degradation of performance. In this paper we will report about the results of the environmental tests with the cameras, the integration of the camera in the SOFIA tracker and the current status of the upgrade project.

AMOS SA has been awarded of the contract for the design, manufacturing, assembly, tests and on site installation (Devasthal, Nainital in central Himalayan region) of the 3.6 m Indo-Belgian Devasthal Optical Telescope (IDOT). The telescope has a Ritchey-Chrétien optical configuration with a Cassegrain focus equipped with one axial port and two side ports. The meniscus primary mirror is active and is supported by pneumatic actuators. The mount is an Alt-Az type with for the azimuth axis a 5 m diameter hydrostatic track. The telescope was completely assembled and tested in AMOS workshop. This step is completed and successful. The telescope is now ready for shipment to Nainital. This paper describes the test campaign at sub-system and system level that has taken place to demonstrate that the telescope satisfies the main system requirements. Besides of the functionality of the telescope, the units interacting with the image quality or the tracking performance were plenty tested. Some selected tests directly connected to the performance of the telescope are also looked specifically in this paper.

The integration of the 2m Fraunhofer telescope started in August 2011 at the Mt. Wendelstein observatory. The logistics of the project are a key problem of the integration as the observatory has no road access. All large or heavy components inlcuding the primary mirror were successfully delivered by helicopter. Meanwhile, they are integrated in the telescope. The special design features of this alt-az telescope are its compactness and the low-ghost wide field optics (0.7 deg. f.o.v. diameter). We will briefly report on tests of the building and of the telescope system before the telescope moved to the mountain. The integration at the observatory and the first astronomical performances tests of the telescopes are discussed, and a brief update on the status of its instruments is presented. We comment on the cleaning and recoating strategy for the primary mirror based on sample tests.

The Southern African Large Telescope (SALT) began its re-commissioning phase in April 2011 following the completion of remedial engineering work on the telescope and the major science instrument, the Robert Stobie Spectrograph (RSS). The engineering work required modifications to the spherical aberration corrector, in order to improve the telescope’s image quality, and RSS, to improve its throughput. Positive test results included delivery of sub-arcsecond images, essentially meeting the original telescope image quality specifications and exhibiting none of the previous field-dependent aberrations, while the RSS has shown greatly improved efficiency performance. SALT has since transitioned to science operations, as from 1 September 2011, following the first open call for charged science proposals from the SALT partners. This paper discusses the current performance of SALT and it First Generation instruments, some initial science results, the proposal process and the operational model for the telescope.

The QUIJOTE (Q-U-I JOint Tenerife) CMB Experiment will operate at the Teide Observatory with the aim of characterizing the polarisation of the CMB and other processes of Galactic and extragalactic emission in the frequency range of 10-40GHz and at large and medium angular scales. The first of the two QUIJOTE telescopes and the first multi-frequency (10-30GHz) instrument are already built and have been tested in the laboratory. QUIJOTE-CMB will be a valuable complement at low frequencies for the Planck mission, and will have the required sensitivity to detect a primordial gravitational-wave component if the tensor-to-scalar ratio is larger than r = 0.05.

A concept study is underway to upgrade the existing 3.6 meter Canada-France-Hawaii Telescope (CFHT) to a 10 meter class, wide-field, dedicated, spectroscopic facility, which will be the sole astronomical resource capable of obtaining deep, spectroscopic follow-up data to the wealth of photometric and astrometric surveys planned for the next decade, and which is designed to tackle driving science questions on the formation of the Milky Way galaxy and the characterization and nature of dark energy. This unique facility will operate at low (R ∼ 2000), intermediate (R ∼ 6000) and high (R ∼ 20000) resolutions over the wavelength range 370 ≤ λ≤ 1300nm, and will obtain up to 3200 simultaneous spectra per pointing over a 1.5 square degree field. Unlike all other proposed or planned wide field spectroscopic facilities, this “Next Generation CFHT” will combine the power of a 10m aperture with exquisite observing conditions and a mandate for dedicated spectroscopic studies to enable transformative science programs in fields as diverse as exoplanetary host characterization, the interstellar medium, stars and stellar astrophysics, the Milky Way galaxy, the Local Group, nearby galaxies and clusters, galaxy evolution, the inter-galactic medium, dark energy and cosmology. A new collaboration must be formed to make this necessary facility into a reality, and currently nearly 60 scientists from 11 different communities - Australia, Brazil, Canada, China, France, Hawaii, India, Japan, South Korea, Taiwan, USA - are involved in defining the science requirements and survey strategies. Here, we discuss the origins of this project, its motivations, the key science and its flow-down requirements. An accompanying article describes the technical studies completed to date. The final concept study will be submitted to the CFHT Board and Science Advisory Committee in Fall 2012, with first light for the facility aiming to be in the early 2020s.

A sophisticated method for the observation of ultra-high-energy cosmic rays (UHECRs) is the fluorescence detection technique of extensive air showers (EAS). FAMOUS will be a small fluorescence telescope, instrumented with silicon photomultipliers (SiPMs) as highly-sensitive light detectors. In comparison to photomultiplier tubes, SiPMs promise to have a higher photon-detection-efficiency. An increase in sensitivity allows to detect more distant and lower energy showers which will contribute to an enrichment of the current understanding of the development of EAS and the chemical composition of UHECRs.

We present the concept of a new instrument dedicated to modeling turbulence inside the dome and in the surface layer. It consists of using parallel laser beams separated by non redundant baselines between 0.1 and 2-3m and measuring Angle-of-Arrival (AA) fluctuations from spots displacements on a CCD. We use weighted least-square method to fit the measured AA longitudinal and transverse covariances with theoretical forms deduced from the usual models of turbulence. Then, the whole parameters characterizing this turbulence are provided from a complete spatio-temporal analysis of AA fluctuations. Thus, the surface layer turbulence energy in terms of C²_N constant is provided from the AA structure function as in the DIMM instrument.

Deployable Shack-Hartmann wavefront sensors (WFS) for the f/5 and f/9 secondary configurations have been used at the 6.5-meter MMT Observatory (MMTO) since 2003. Probe mirrors for these WFS's are moved into the optical path of the telescope between scientific observations multiple times each night. Results from the wavefront measurements are then used to bend the primary mirror (M1) and to reposition the secondary mirror (M2) to correct for wavefront errors. In addition to measuring the optical wavefront error, the Shack-Hartmann data are used to determine the delivered seeing using the measured spot sizes. This study attempts to analyze the more than 75,000 WFS measurements and associated seeing values obtained at the MMTO since 2003. The overall WFS data reduction and analysis procedure is discussed. This data analysis includes: 1) finding the spots in each image, 2) centroiding the spots, 3) measuring a point-spread function, 4) determining an average spot width and a derived seeing value, and 5) computing the best-fit Zernike polynomial coefficients. Wavefront slopes are calculated from spot displacements and wavefront aberrations are fit with a 19-term Zernike polynomial. As part of this study, the WFS-derived seeing values are correlated with other observing parameters, such as mirror-air temperature contrasts. Finally, seasonal climate and local weather (e.g., prevailing wind direction) effects on astronomical seeing are evaluated.

Starting in 2009, MMTO began design and installation of a new set of electronics to measure a set of radiallydistributed type T thermocouples installed after the primary mirror polishing was completed. These thermocouples are arranged in both single measurement points and as thermopiles for differential temperature sensing. Since the goal of the primary mirror temperature control system is to minimize mirror seeing and mirror figure errors induced by temperature variation across the primary mirror, it depends on excellent accuracy from the temperature sensing system. The new electronics encompass on-board cold-junction compensation, real-time ITS-90 curve fitting, and Ethernet connectivity to the data servers running in the MMTO software infrastructure. We describe the hardware design, system wiring, and software used in this system.