This PDF file contains the front matter associated with SPIE Proceedings Volume 7733, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Answering well-known fundamental questions is usually regarded as the major goal of science. Discovery of other unknown and fundamental questions is, however, even more important. Recognition that "we didn't know anything" is the basic scientific driver for the next generation. Cosmology indeed enjoys such an exciting epoch. What is the composition of our universe ? This is one of the well-known fundamental questions that philosophers, astronomers and physicists have tried to answer for centuries. Around the end of the last century, cosmologists finally recognized that "We didn't know anything". Except for atoms that comprise slightly less than 5% of the universe, our universe is apparently dominated by unknown components; 23% is the known unknown (dark matter), and 72% is the unknown unknown (dark energy). In the course of answering a known fundamental question, we have discovered an unknown, even more fundamental, question: "What is dark matter? What is dark energy?" There are a variety of realistic particle physics models for dark matter, and its experimental detection may be within reach. On the other hand, it is fair to say that there is no widely accepted theoretical framework to describe the nature of dark energy. This is exactly why astronomical observations will play a key role in unveiling its nature. I will review our current understanding of the "dark sky", and then present on-going Japanese project, SuMIRe, to discover even more unexpected questions.

Over the past decade, sky surveys such as the Sloan Digital Sky Survey (SDSS) have proven the power of large data sets for answering fundamental astrophysical questions. This observational progress, based on a synergy of advances in telescope construction, detectors, and information technology, has had a dramatic impact on nearly all fields of astronomy, and areas of fundamental physics. The next-generation instruments, and the surveys that will be made with them, will maintain this revolutionary progress. The hardware and computational technical challenges and the exciting science opportunities are attracting scientists and engineers from astronomy, optics, low-light-level detectors, high-energy physics, statistics, and computer science. The history of astronomy has taught us repeatedly that there are surprises whenever we view the sky in a new way. This will be particularly true of discoveries emerging from a new generation of sky surveys. Imaging data from large ground-based active optics telescopes with sufficient étendue can address many scientific missions simultaneously. These new investigations will rely on the statistical precision obtainable with billions of objects. For the first time, the full sky will be surveyed deep and fast, opening a new window on a universe of faint moving and distant exploding objects as well as unraveling the mystery of dark energy.

The GTC (Gran Telescopio Canarias) is an optical and IR telescope, with a 10,4 meter segmented primary, installed at the Observatorio del Roque de Los Muchachos (ORM) on the island of La Palma. GTC commissioning started in July 2007 when First Light was achieved. GTC regular scientific operations started at the beginning of 2009 with its first science instrument: OSIRIS, a visible camera with tunable filter and low-resolution multi-object spectroscopic capability. Since that time science operation and telescope and instrument development activities alternate in using the available telescope time. Later in 2010 the second science instrument will be commissioned: CanariCam, a thermal-IR camera and low-resolution spectrograph with polarimetric and coronagraphic capabilities. This paper presents the telescope commissioning process, the problems encountered and shows some of the performance aspects. First science results will also be presented to demonstrate the current capabilities of the GTC facility.

VISTA, the Visible and Infrared Survey Telescope for Astronomy, is a 4-m class 1.65-degree wide field near-IR survey telescope with 0.34 arcsec pixels. VISTA was successfully commissioned and has been making surveys since 15 October 2009, and was formally accepted as a part of ESO's Cerro Paranal Observatory on 10 December 2009. We summarise the design and build process, report on commissioning and the as-built status. The most novel aspects of the system design have proved to all work well. We report the measured on-sky system performance that confirms that VISTA works as expected.

Ludwig-Maximilians-Universitat Munchen operates an astrophysical observatory on the summit of Mt. Wendelstein¹ which will be equipped with a modern 2m-class, robotic telescope. The plan is to operate one of the most efficient robotic 2m telescopes in Europe in order to offer optimal scientific opportunities for our researchers and maintain highest standards for the education of students. The 2m Fraunhofer telescope in its new 8.5m dome has a modern, very compact alt.-azimuth design. Two Nasmyth ports will harbor a wide-field camera (WWFI²), a medium field multi-channel camera (3kk³), a low resolution IFU spectrograph (VIRUSW⁴) and a high resolution spectrograph (upgraded FOCES⁵). All instruments will be simultaneously ready for remote or robotic observations. The telescope is designed as a 3-mirror f/7.8 system and should maintain the excellent (< 0.8" median) seeing of the site1 over a field of view (f.o.v.) of 0.7 deg diameter with a field corrector for the wide field port at optical wavelength. The second port provides a f.o.v. of 60 arcmin² without any corrector optics. It is optimized for simultaneous optical and NIR imaging as well as field spectroscopy and echelle high resolution spectroscopy over the full optical wavelength regime.6 Here we present the design of the telescope as well as the scope and projected time line of the overall project.

The University of Tokyo Atacama Observatory (TAO) is a project to construct a 6.5m infrared-optimized telescope at the summit of Co. Chajnantor, 5,640 m altitude, in northern Chile, promoted by Institute of Astronomy, University of Tokyo. Thanks to the high altitude and low water vapor, continuous window from 0.9 to 2.5μm as well as new windows at wavelength longer than 25μm appears. The site shows extremely low precipitable water vapor of 0.5mm (25 percentile), and fraction of usable night is more than 80%. Measured median seeing is 0".69, which is comparable or better than major observatories over the world. Prior to the 6.5m telescope, a 1m pathfinder telescope called miniTAO is installed and started observations in 2009. Its successes of Paschen α imaging at 1.875 μm and mid-infrared observations at 30μm confirm promising capabilities of the site. The 6.5m telescope is now at a design phase, and two facility instruments are now being constructed, which are a near-infrared imager/multi-object spectrograph with a field of view of 9'.6 and a mid-infrared imager/spectrograph for observations in 2 to 38μm.

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) project has completed its engineering work, and is going to finish commissioning around the end of 2010. The LAMOST telescope is with both large aperture and wide field of view to achieve the large scale spectroscopic survey observation. It is an innovative large aperture meridian active reflecting Schmidt configuration achieved by an active deformable Schmidt mirror, which could not be realized by the traditional optical system. Its primary mirror and active Schmidt mirror are both segmented, and composed of 37 and 24 hexagonal sub-mirrors respectively. A new active optics method succesfully developed in the active deformable Schmidt mirror of LAMOST. It is a conbination of the thin deformable mirror active optics and segmented active optics. This paper presents the optical performance of the telescope of LAMOST during optical test. It is shown that LAMOST project successfully resolving the big technical challenges, and making the progress in active optics and telescope technology.

The Discovery Channel Telescope (DCT) is a 4.3-meter astronomical research telescope being built in northern Arizona as a partnership between Discovery Communications and Lowell Observatory. The telescope will be able to support substantial instrument payloads at Cassegrain, Nasmyth, and prime foci, and high observing cadences. The first-light configuration will be as an f/6.1 Ritchey-Chrétien at Cassegrain with a 30 arc-minute field-of-view. Major facility work is complete, and the telescope is currently in the integration phase with first-light anticipated in 2011. We present an overview of the design and progress to date, and include plans for final integration, commissioning, and early science.

The all sky spectoscopic survey is very important both in extra-galactic and Galactic studies. The Large-Sky-Area Multi-object Fiber Spectroscopic Telescope (LAMOST) has successfully completed its engineering work and inaugurated in October of 2008. Now it is in the commissioning stage. In pursuit of the all sky spectroscopic survey, a southern LAMOST is proposed. Tecnically, the Southern LAMOST will be mainly a copy of present LAMOST in Xinglong, China, which is located at about latitute +40 degrees. Modifications are to be made for much better image quality and thinner optical fibers to match with the better seeing condition in the Southern site. There will be 6000 or 8000 optical fibers used on the focal surface to get the highest spectrum acquiring rate, and will be equipted with about 12 to 16 spectrographs with 24 to 32 CCD cameras. Southern LAMOST is going to be built by international collaboration.

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 Arizona uses two 8.4-meter diameter 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 cophased imaging along with adaptive optics gives the telescope the diffraction-limited resolution of a 22.65-meter telescope. Binocular imaging with two co-pointed prime focus cameras began in Fall 2007, and science observing continues routinely. We will describe the scientific results and technical challenges of monocular Gregorian focus observations starting in Spring 2008. Commissioning of the first Gregorian spectrometer (LUCIFER1) has been completed with a rigid secondary mirror, and science observations have begun in December 2009. The telescope uses two F/15 adaptive secondaries to correct atmospheric turbulence. The first of these adaptive mirrors has been tested in Italy with the adaptive loop closed, and arrived at the telescope in February 2010. The first adaptive optics images were achieved on-sky in May 2010. The Direct Gregorian focus has been prepared for the arrival of the second Gregorian spectrometer (MODS1).

The Large Synoptic Survey Telescope (LSST) Project is a public-private partnership that is well into the design and development of the complete observatory system to conduct a wide fast deep survey and to process and serve the data. The telescope has a 3-mirror wide field optical system with an 8.4 meter primary, 3.4 meter secondary, and 5 meter tertiary mirror. The reflective optics feed three refractive elements and a 64 cm 3.2 gigapixel camera. The LSST data management system will reduce, transport, alert and archive the roughly 15 terabytes of data produced nightly, and will serve the raw and catalog data accumulating at an average of 7 petabytes per year to the community without any proprietary period. The project has completed several data challenges designed to prototype and test the data management system to significant pre-construction levels. The project continues to attract institutional partners and has acquired non-federal funding sufficient to construct the primary mirror, already in progress at the University of Arizona, build the secondary mirror substrate, completed by Corning, and fund detector prototype efforts, several that have been tested on the sky. A focus of the project is systems engineering, risk reduction through prototyping and major efforts in image simulation and operation simulations. The project has submitted a proposal for construction to the National Science Foundation Major Research Equipment and Facilities Construction (MREFC) program and has prepared project advocacy papers for the National Research Council's Astronomy 2010 Decadal Survey. The project is preparing for a 2012 construction funding authorization.

Pan-STARRS is a highly cost-effective, modular and scalable approach to wide-field optical/NIR imaging. It uses 1.8m telescopes with very large (7 square degree) field of view and revolutionary1.4 billion pixel CCD cameras with low noise and rapid read-out to provide broad-band imaging from 400-1000nm wavelength. The first single telescope system, PS1, has been deployed on Haleakala on Maui, and has been collecting science quality survey data for approximately six months. PS1 will be joined by a second telescope PS2 in approximately 18 months. A four aperture system is planned to become operational following the end of the PS1 mission. This will be able to scan the entire visible sky to approximately 24^th magnitude in less than a week, thereby meeting the goals set out by the NAS 2000 decadal review for a "Large Synoptic Sky Telescope". Here we review the technical design, and give an update on the progress that has been made with the PS1 system.

The Large Synoptic Survey Telescope (LSST) is a large (8.4 meter) wide-field (3.5 degree) survey telescope, which will be located on the summit of Cerro Pachón in Chile. The survey mission requires a short slew and settling time of 5 seconds for a 3.5 degree slew. This is significantly faster than similar aperture telescopes. Since the optical system does not include a fast steering mirror the telescope has stringent vibration limitations during observation. Meeting these requirements is facilitated by the compact mount riding on a robust pier which produces high natural frequencies, an advanced control system to minimize vibration excitation and reaction mass dampers. The telescope mount design is an altitude over azimuth welded and bolted assembly fabricated from mild steel. It supports the primary / tertiary mirror cell assembly, the secondary mirror cell assembly and the camera assembly. The mount design enables the removal of these optical assemblies for servicing and recoating. Retractable / deployable platforms have also been provided for accessing the camera on telescope. As a result of the wide field of view, the optical system is unusually susceptible to stray light consequently the mount must incorporate substantial light baffling. The dynamic characteristics of the steel reinforced concrete pier were enhanced by utilizing two different wall thicknesses, an unusually large diameter of 16 meter and anchoring the foundation in unweathered bedrock. The entire pier and mount assembly has been designed to be invariant with azimuth and elevation angle to enhance the effectiveness of the advanced control system.

The 4m Advance Technology Solar Telescope (ATST) will be the most powerful solar telescope and the world's leading ground-based resource for studying solar magnetism that controls the solar wind, flares, coronal mass ejections and variability in the Sun's output. The project has successfully passed its final design review and the Environmental Impact Study for construction of ATST on Haleakala, Maui, HI has been concluded in December of 2009. The project is now entering its construction phase. As its highest priority science driver ATST shall provide high resolution and high sensitivity observations of the dynamic solar magnetic fields throughout the solar atmosphere, including the corona at infrared wavelengths. With its 4 m aperture, ATST will resolve features at 0."03 at visible wavelengths and obtain 0."1 resolution at the magnetically highly sensitive near infrared wavelengths. A high order adaptive optics system delivers a corrected beam to the initial set of state-of-the-art, facility class instrumentation located in the coudé laboratory facility. The initial set of first generation instruments consists of five facility class instruments, including imagers and spectropolarimeters. The high polarimetric sensitivity and accuracy required for measurements of the illusive solar magnetic fields place strong constraints on the polarization analysis and calibration. Development and construction of a fourmeter solar telescope presents many technical challenges, including thermal control of the enclosure, telescope structure and optics and wavefront control. A brief overview of the science goals and observational requirements of the ATST will be given, followed by a summary of the design status of the telescope and its instrumentation, including design status of major subsystems, such as the telescope mount assembly, enclosure, mirror assemblies, and wavefront correction

The European Solar Telescope is a project for a 4-meter class telescope to be located in the Canary Islands. EST is promoted by the European Association for Solar Telescopes (EAST). This is a consortium formed by a number of research organizations from fifteen European countries (Austria, Croatia, Czech Republic, France, Germany, Hungary, Italy, the Netherlands, Norway, Poland, Slovak Republic, Spain, Sweden, Switzerland, and United Kingdom). EST will specialize in high spatial and temporal resolution using diverse instruments that can efficiently produce two-dimensional spectropolarimetric information of the thermal, dynamic and magnetic properties of the plasma over many scale heights in the solar atmosphere. In this contribution, the status of the development of the Design Study of EST is presented, emphasizing the most important aspects of the optical design, mechanical structure, AO and MCAO systems for wavefront correction, instruments and polarization analysis.

India is planning a new solar telescope with an aperture of 2-m for carrying out high resolution studies of the Sun. Site characterization is underway at high altitude locations in the Himalayan mountains. A detailed concept design for NLST (National Large Solar Telescope) has been completed. The optical design of the telescope is optimized for high optical throughput and uses a minimum number of optical elements. A high order AO system is integrated part of the design that works with a modest Fried's parameter of 7-cm to give diffraction limited performance. The telescope will be equipped with a suite of post-focus instruments including a high resolution spectrograph and a polarimeter. NLST will also be used for carrying out stellar observations during the night. The mechanical design of the telescope, building, and the innovative dome is optimized to take advantage of the natural air flush which will help to keep the open telescope in temperature equilibrium. After its completion (planned for 2014), NLST will fill a gap in longitude between the major solar facilities in USA and Europe, and it will be for years the largest solar telescope in the world

In the context of the EST design study for a 4m-class solar telescope and a study for large open-foldable domes of the Dutch Technology Foundation STW, a design is made for the 20 to 30m diameter range. Detailed designs are made for three specific diameter sizes: 23, 28 and 33m. Smaller-size open-foldable domes based on tensioned cloth and in use at the Dutch Open Telescope (7m) and the GREGOR (9m) have proven to be all-weather stable and very effective for good seeing conditions for solar telescopes. The cloth has shown no degradation over the past 14 (DOT) resp. 6 (GREGOR) years of experience and no permanent elongation with the frequent de-tensioning and tensioning during opening and closing. The application of cloth permits a dome design leaving, when opened, the telescope completely free without any structure over the telescope and no massive structures besides or under it. Basis for the new design is the available prestretched stable cloth, which is nowadays produced in much stronger qualities than used for DOT and GREGOR. The larger curvature radius requires larger tension in the cloth, but combination with stronger cloth fits for the upscaling. Calculations show that the steel construction geometries of the GREGOR dome can be upscaled with a few adjustments. Bearings and drives remain within normal sizes. Cost calculations show that open-foldable domes of this size are remarkably lower in price than closed domes. In addition, an interesting option is presented for a semi-transparent windshield of which the position can be adapted to the wind direction. This shield gives an effective wind protection of the region around the primary mirror without disturbing the wind flows above the shield and without stagnant air or big eddies behind it. It is storm safe and the costs are only a fraction of the open-foldable dome costs.

With the integration of a 1-meter Cesic primary mirror the GREGOR telescope pre-commissioning started. This is the first time, that the entire light path has seen sunlight. The pre-commissioning period includes testing of the main optics, adaptive optics, cooling system, and pointing system. This time was also used to install a near-infrared grating spectro-polarimeter and a 2D-spectropolarimeter for the visible range as first-light science instruments. As soon as the final 1.5 meter primary mirror is installed, commissioning will be completed, and an extended phase of science verification will follow. In the near future, GREGOR will be equipped with a multi-conjugate adaptive optics system that is presently under development at KIS.

SOFIA, the Stratospheric Observatory for Infrared Astronomy, is a specially modified Boeing 747SP aircraft with a 2.7- m telescope. Flying above more than 99% of the water vapor in the Earth's atmosphere, SOFIA will enable observations of large regions of the infrared and submillimeter that are normally opaque to terrestrial observatories. A joint project of NASA and DLR, SOFIA has completed a series of major flight tests leading up to the Initial Science Flights this year. In particular, SOFIA has recently completed its first observations through the telescope. This paper gives an overview of the facility and reports on the recent progress in the development of this major astronomical facility including the First Light observations with the FORCAST infrared camera.

The Stratospheric TeraHertz Observatory (STO) is a NASA funded, Long Duration Balloon (LDB) experiment designed to address a key problem in modern astrophysics: understanding the Life Cycle of the Interstellar Medium (ISM). STO will survey a section of the Galactic plane in the dominant interstellar cooling line [C II] (1.9 THz) and the important star formation tracer [N II] (1.46 THz) at ~1 arc minute angular resolution, sufficient to spatially resolve atomic, ionic and molecular clouds at 10 kpc. STO itself has three main components; 1) an 80 cm optical telescope, 2) a THz instrument package, and 3) a gondola [1]. Both the telescope and gondola have flown on previous experiments [2,3]. They have been reoptimized for the current mission. The science flight receiver package will contain four [CII] and four [NII] HEB mixers, coupled to a digital spectrometer. The first engineering test flight of STO was from Ft. Sumner, NM on October 15, 2009. The ~30 day science flight is scheduled for December 2011.

One of the most challenging requirements for the Stratospheric Observatory for Infrared Astronomy (SOFIA) is the pointing stability of 0.2 arcseconds (rms) of its 2.7 m telescope onboard a Boeing 747SP. To support the analysis of pointing disturbances in flight, an EM-CCD camera has been prepared to measure star positions in the focal plane at speeds up to about 400 frames per second. Currently, the camera is planned to be mounted for special engineering flights, a procedure that requires overhead for mechanical work and optical alignment, including star tests on the night sky from the ground. This paper summarizes the status of the project and explores possibilities to mount the camera permanently to the SOFIA telescope. Permanent mounting would make it available for continuous performance monitoring and as a trouble shooting tool if needed. In addition, the camera could serve as a versatile high speed photometer in the visible and very near IR wavelength range for astronomical observations, e.g. for the photometry of stellar occultations and of transits of extra-solar planets.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a 2.5m infrared telescope build into a Boeing 747SP. During observations the telescope will not only be subject to aircraft vibrations and maneuver loads - by opening a large door to give the observatory an unhindered view of the sky, there will also be aerodynamic and aeroacoustic disturbances. A critical factor in the overall telescope performance is the SOFIA Secondary Mirror Assembly. The 35cm silicon carbide mirror is mounted on the Secondary Mirror Mechanism, which has five degrees-of-freedom (rotation about line of sight is blocked) and consists of two parts: The slow moving base for focusing and centering, and on top of that the Tilt Chop Mechanism (TCM) for chopping with a frequency of up to 20Hz and a chop throw of up to 10arcmin. A new controller for the TCM is introduced in this paper in order to meet the stringent performance requirements for the chopper. A state space controller is chosen that combines a feedback path for steady state behavior with a model-based feed forward controller for improved settling time performance. The paper explains the modeling of the TCM via a grey box model approach optimized with system identification data and compares simulated with measured data. Then the structure of the controller is explained and Matlab/Simulink simulations are presented. The simulation results are compared to measurements taken with the real system on ground and finally flight test results with open and closed door are discussed.

During observation flights the telescope structure of the Stratospheric Observatory for Infrared Astronomy (SOFIA) is subject to disturbance excitations over a wide frequency band. The sources can be separated into two groups: inertial excitation caused by vibration of the airborne platform, and aerodynamic excitation that acts on the telescope assembly (TA) through an open port cavity. These disturbance sources constitute a major difference of SOFIA to other ground based and space observatories and achieving the required pointing accuracy of 1 arcsecond cumulative rms or better below 70 Hz in this environment is driving the design of the TA pointing and control system. In the current design it consists of two parts, the rigid body attitude control system and a feed forward based compensator of flexible TA deformation. This paper discusses the characterization and control system tuning of the as-built system. It is a process that integrates the study of the structural dynamic behavior of the TA, the resulting image motion in the focal plane, and the design and implementation of active control systems. Ground tests, which are performed under controlled experimental conditions, and in-flight characterization tests, both leading up to the early science performance capabilities of the observatory, are addressed.

The goal of the Stratospheric Observatory for Infrared Astronomy (SOFIA) is to point its airborne telescope at astronomical targets stable within 0.2 arcseconds (rms). However, the pointing stability will be affected in flight by aircraft vibrations and movements and constantly changing aerodynamic conditions within the open telescope compartment. Model calculations indicate that initially the deviations from targets may be at the order of several arcseconds. The plan is to carefully analyse and characterize all disturbances and then gradually fine tune the telescope's attitude control system to improve the pointing stability. To optically measure how star images change their position in the focal plane, an Andor DU-888 electronmultiplying (EM) CCD camera will be mounted to the telescope instead of its standard tracking camera. The new camera, dubbed Fast Diagnostic Camera (FDC) has been extensively tested and characterized in the laboratory and on ground based telescopes. In ground tests on the SOFIA telescope system it proofed its capabilities by sampling star images with frame rates up to 400 frames per second. From this data the star's location (centroid) in the focal plane can be calculated every 1/400th second and by means of a Fourier transformation, the star's movement power spectrum can be derived for frequencies up to 200 Hz. Eigenfrequencies and the overall shape of the measured spectrum confirm the previous model calculations. With known disturbances introduced to the telescope's fine drive system, the FDC data can be used to determine the system's transfer function. These data, when measured in flight will be critical for the refinement of the attitude control system. Another subsystem of the telescope that was characterized using FDC data was the chopping secondary mirror. By monitoring a star centroid at high speed while chopping, the chopping mechanism and its properties could be analyzed. This paper will describe the EM-CCD camera and its characteristics and will report on the tests that lead up to its first use in a SOFIA flight.

We present the design of a MegaTORTORA telescope (and its prototype, mini-MegaTORTORA, presently in construction at Special Astrophysical Observatory) - modular, multi-purpose, scalable grid of optical cameras based on commercially available objectives and fast CCDs, able to operate with sub-second temporal resolution in both wide-field monitoring regime with all objectives observing different regions of the sky as well as in narrow-field follow-up mode with co-aligned channels and installed color and polarimetric filters for detailed investigation of selected objects, and to change the regime of operation on a sub-second time scale.

During the last years, a number of telescopes and instruments have been dedicated to the follow-up of GRBs: recent studies of the prompt emission (see for instance GRB080319B) and of their afterglows, evidenced a series of phenomena that do not fit very well within the standard fireball model. In those cases, optical observations were fundamental to distinguish among different emission mechanisms and models. In particular, simultaneous observation in various optical filters became essential to understand the physics, and we discovered the need to have a detailed high time resolution follow up. Finally, recent observations of the polarization in GRB 090102 clearly indicate the presence of an ordered magnetic field favoring the electromagnetic outflows models. This is, however, only one case and, in order to detail properly the model, we need a bit of statistics. But, after the Swift launch, the average observed intensity of GRB afterglows showed to be lower than thought before. Robotic telescopes, as demonstrated by REM, ROTSE, TAROT, etc. (but see also the GROND set up) is clearly the winning strategy. Indeed, as we will also briefly discuss later on, the understanding of the prompt emission mechanism depends on the observations covering the first few hundreds seconds since the beginning of the event with high temporal resolution. To tackle these problems and track down a realistic model, we started the conceptual design and phase A study of a 4 meter class, fast-pointing telescope (40 sec on target), equipped with multichannel imagers, from Visible to Near Infrared (Codevisir/Pathos). In the study we explored all the different parts of the project, from the telescope to the instrumental suite to data managing and analysis, to the dome and site issue. Contacts with industry have been fruitful in understanding the actual feasibility of building such a complex machine and no show stoppers have been identified, even if some critical points should be better addressed in the Phase B study. In this paper, we present the main results of the feasibility study we performed.

A number of scientific observations take advantage of the use of robotic, fast pointing telescopes; in particular, fast reacting small telescopes were especially useful for gamma ray burst follow-up which now require better performances and greater telescope size. However, increasing telescope size could imply some limitations in terms of operability and technological solutions. In order to select the best telescope configuration it is necessary to take into account mechanical set up, pointing strategy, wind effects and the resulting effective costs. This paper will investigate and compare the characteristics of traditional alt-az and alt-alt telescope configurations considering also an innovative alt-alt set up to be developed as an alternative to the mainstream layout of present medium class telescopes. In the alt-alt case the system exploits the heritage of larger telescope projects like LBT, coupled with a more traditional fork mounted to match the alt-alt kinematics, so obtaining a more stable machine and minimizing the blind spot limitation.

Current trends in astronomical research necessitate a large number of small to medium sized telescopes be commissioned to support and augment the science goals of larger ground-based observatories and space observatories. The science mission requirements for these telescopes vary widely, yet the critical design requirements for the telescopes are largely consistent across many missions. This paper clarifies the critical functional and performance parameters of a gimbaled telescope system as dictated by three significant classes of telescope missions: laser transmission, wide area surveys and pointed surveys. Within these classifications several specific example science missions are considered from which specific telescope functional requirements are derived. Detailed telescope performance requirements are then evaluated from a systems engineering perspective, highlighting typical performance that may be expected from a modern telescope. Additional commentary is provided on the probable feasibility of upgrading older facilities in contrast to commissioning new telescopes systems. Based on the predictions of the NSF / NOAO sponsored ReSTAR report, it is assumed that the demand for highobservation- volume pointed surveys will increase rapidly within the next ten years. A case is made for the high science value of high gimbal slew rates on the basis of effective throughput in pointed survey applications.

The QUIJOTE CMB experiment aims to characterize the polarization of the CMB in the frequency range 10-30 GHz and large angular scales. It will be installed in the Teide Observatory, following the projects that the Anisotropy of the Cosmic Microwave Background group has developed in the past (Tenerife experiment, IAC-Bartol experiment...) and is running at the present time (VSA, Cosmosomas). The QUIJOTE CMB experiment will consist of two telescopes which will be installed inside a unique enclosure, which is already constructed. The layout of both telescopes is based on an altazimuth mount supporting a primary and a secondary mirror disposed in a offset Gregorian Dragon scheme. The use of industrial-like fabrication techniques, such as sand-mould casting, CNC machining, and laser tracker measuring for alignment, provided the required performances for microwave observation. A fast-track construction scheme, altogether with the use of these fabrication techniques allowed designing and manufacturing the opto-mechanics of the telescope in 14 months prior to delivery for final start-up in December 2008.

We describe a 1p8m f/6 Cassegrain optical system that creates a 1.42° FOV with near diffraction limited images from 400nm to 1100nm with full-field distortion less than 0.01%. The astronomical application for this optical system is the CCD/Transit Instrument with Innovative Instrumentation (CTI-II), designed to produce a highly precise photometric and astrometric survey of a complete strip of sky in the northern hemisphere. We describe the scientific observation program and supporting optical design for the telescope. The all-spherical, five lens field corrector represents a very capable optical system that works well with many other astronomical telescopes such as SDSS, Pan-STARRS, SkyMapper, ESO's VST, the WIYN ODI, and the MMT WFC. In many cases, using a five lens corrector exceeded the optical performance of the original published system designs. Conversely, these and other optical concepts compromised the performance of the CTI-II design. The CTI-II design is similar to many other wide-field telescope and imaging camera designs, thus the design is of potential general use in astronomy.

This paper describes the current status of the Large Millimeter Telescope (LMT), the near-term plans for the telescope and the initial suite of instrumentation. The LMT is a bi-national collaboration between Mexico and the USA, led by the Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE) and the University of Massachusetts at Amherst, to construct, commission and operate a 50m-diameter millimeter-wave radio telescope. Construction activities are nearly complete at the 4600m LMT site on the summit of Volcán Sierra Negra, an extinct volcano in the Mexican state of Puebla. Full movement of the telescope, under computer control in both azimuth and elevation, has been achieved. The commissioning and scientific operation of the LMT is divided into two major phases. As part of phase 1, the installation of precision surface segments for millimeter-wave operation within the inner 32m-diameter of the LMT surface is now complete. The alignment of these surface segments is underway. The telescope (in its 32-m diameter format) will be commissioned later this year with first-light scientific observations at 1mm and 3mm expected in early 2011. In phase 2, we will continue the installation and alignment of the remainder of the reflector surface, following which the final commissioning of the full 50-m LMT will take place. The LMT antenna, outfitted with its initial complement of scientific instruments, will be a world-leading scientific research facility for millimeter-wave astronomy.

The Atacama Large Millimeter Array (ALMA) consists of a large number of 12 m diameter antennas that will operate up to 950GHz. The mechanical performances in terms of surface accuracy, pointing stability and residual delay are very tight. The antennas must work at full performances in free air during night and day with also the request to observe the sun. The mechanical performances are affected by all the not repeatable error sources and in particular by the temperature variations and wind component blowing from different directions. The design of the antenna has been done in order to have a very light and stiff structure, in particular all the elevation structure is in carbon fibre with also a very low thermal expansion coefficient, but to achieve the ALMA specification, two different systems able to predict the above error sources have been implemented in the control of the antenna. The first system is composed by a determined number of thermal sensors distributed in the alidade of the antenna (is the only part in steel ) and compensates the elevation axis deformation due to the temperature variation by means of a deformation matrix. The second system is based on two high accuracy inclinometers with a very short recovery time opportunely placed on the antenna and correct the wind induced errors. These innovative systems and instruments have been design and tested in the prototype antenna to the production phase.

We present here the systems aimed to measure and minimize the pointing errors for the Sardinia Radio Telescope: they consist of an optical telescope to measure errors due to the mechanical structure deformations and a lasers system for the errors due to the subreflector displacement. We show here the results of the tests that we have done on the Medicina 32 meters VLBI radio telescope. The measurements demonstrate we can measure the pointing errors of the mechanical structure, with an accuracy of about ~1 arcsec. Moreover, we show the technique to measure the displacement of the subreflector, placed in the SRT at 22 meters from the main mirror, within ±0.1 mm from its optimal position. These measurements show that we can obtain the needed accuracy to correct also the non repeatable pointing errors, which arise on time scale varying from seconds to minutes.

The Atacama Large Millimeter/submillimeter Array (ALMA) is an international facility at an advanced stage of construction in the Atacama region of northern Chile. ALMA will consist of two arrays of high-precision antennas: one made up of twelve 7-meter diameter antennas operating in closely-packed configurations of about 50m in diameter, and the other of up to sixty-four 12-meter antennas arranged in configurations with diameters ranging from about 150 meters to 15 km. There will be four more 12-meter antennas to provide the "zero-spacing" information, which is critical for making accurate images of extended objects. The antennas will be equipped with sensitive millimeter-wave receivers covering most of the frequency range 84 to 950 GHz. State-of-the-art microwave, digital, photonic and software systems will capture the signals, transfer them to the central building and correlate them, while maintaining accurate synchronization. ALMA will provide images of a wide range of astronomical objects with great sensitivity and very high spectral resolution. The images will have much higher "fidelity" than those from existing mm/submm telescopes. This paper gives an update on the status of construction and on progress with the testing and scientific commissioning.

The Square Kilometre Array is intended to be the next-generation radio wavelength observatory. With a Key Science program addressing fundamental physics, astronomy, and astrobiology, the SKA will have a collecting area of up to one million square metres spread over at least 3000 km, providing a sensitivity 50 times higher than the Expanded Very Large Array, and an instantaneous field of view (FoV) of at least several tens of square degrees and possibly 250 square degrees. In this paper, we describe the main features of the SKA, paying attention to the design activities around the world, and outline plans for the final design and phased implementation of the telescope.

The Expanded Very Large Array (EVLA) is an international project to improve the scientific capabilities of the Very Large Array (VLA), an aperture synthesis radio telescope consisting of 27, 25-meter diameter antennas distributed in a Y-shaped configuration on the Plains of San Augustin in west-central New Mexico. The EVLA's major science themes include measuring the strength and topology of magnetic fields, enabling unbiased surveys and imaging of dust-shrouded objects that are obscured at other wavelengths, enabling rapid response to and imaging of rapidly evolving transient sources, and tracking the formation and evolution of objects in the universe. The EVLA's primary technical elements include new or upgraded receivers for continuous frequency coverage from 1 to 50 GHz, new local oscillator, intermediate frequency, and wide bandwidth data transmission systems to carry signals with 16 GHz total bandwidth from each antenna, and a new digital correlator with the capability to process this bandwidth with an unprecedented number of frequency channels for an imaging array. The project also includes a new monitor and control system and new software that will provide telescope ease of use. The project was started in 2001 and is on schedule and within budget. Scientific observations with the new correlator started in March 2010. The structural modifications that convert the VLA antennas to the EVLA design were completed in May 2010. The project will be complete in December 2012 when the last receiver will be installed on an antenna.

The CARMA telescope is a heterogeneous array of 10.4, 6.1 and 3.5 m antennas, with antenna configurations providing spacings from ~3.5 m to 2 km. This heterogeneous array is well suited to imaging a wide range of spatial scales. In compact configurations the heterogeneous array provides high quality short spacing data for aperture synthesis. In extended configurations, the antennas can be paired, with 6.1 and 10.4m antennas making science observations in the 3 mm and 1 mm bands, while 3.5 m antennas are simultaneously observing calibration sources within a few degrees in the 1 cm band. This unique Paired Antenna Calibration System allows us to to correct for atmospheric phase fluctuations and make images at 0.15 arcec resolution in a wide range of atmospheric seeing conditions. In this paper we discuss some results and lessons learned using these heterogeneous observing techniques. These results are relevant to all aperture synthesis arrays, including millimeter/submillimeter wavelength arrays like ALMA, and cm/m wavelength arrays like ATA and SKA.

A dominant problem for large, high precision telescopes is the deformation due to temperature changes in the structure. Even for active surface designs such as the Large Millimeter Telescope/Gran Telescopio Milimetrico (LMT), accurate knowledge of the temperature distribution in the structure is necessary in order to adjust the primary reflector panels and make pointing corrections. The design of thermal management system of the LMT consists of a fully-cladded structure, a forced ventilation system, and a collection of temperature sensors distributed throughout the telescope. During the design, both steady-state and dynamic thermal models were developed to predict the thermal behavior. Additionally, some thermal measurements were taken during construction, before the cladding was installed. Since the structure is now completely enclosed with insulating cladding, it is an excellent candidate for thermal imaging at this stage of the commissioning. Thermal images of the structure are presented, showing the actual temperature distribution of the LMT alidade structure and reflector. The images are taken from a consistent set of positions to show the how the structural temperature distribution evolves over day and night conditions.

Two types of field measurements on the Atacama Submillimeter Telescope Experiment 10-m antenna have been made to diagnose antenna oscillations in strong wind gusts and to reduce pointing errors due to static/quasi-static wind loadings. The measurements with seismic accelerometers on the reflector have been compared with those from axis angle encoders. Our results have confirmed that the dominant wind effects are at low frequencies, and have found that twist and pitching motion of yoke arms are the dominant source of pointing jitters and decrease with frequency along the Kolmogorov slope of -5/3. In the range from about 1 to 10 Hz, the servo-loop excites and dominates pointing error oscillations. For azimuth oscillations, the frontal wind has the largest effects, compared with side- or tail-wind. To improve pointing performance against static/quasi-static wind effects, we have implemented and tested an auxiliary auto-pointingcorrection system with a lookup table compiled from all-sky pointing measurements under strong winds, invoking the Taylor's "frozen turbulence" hypothesis. We have successfully demonstrated that use of upwind data from a nearby anemometer helps to reduce the pointing errors of static wind effects from 2.4 " rms (correction OFF) to 1.2 " rms (correction ON) under a mean wind speed of 9.3 m s^-1.

The Large Synoptic Survey Telescope (LSST) primary/tertiary monolithic mirror will be fabricated as a single cast borosilicate substrate that requires an extensive thermal control system. The relatively large coefficient of thermal expansion (CTE) of borosilicate glass requires the thermal system maintain differences throughout the mirror to below 0.1C. The thermal control system is also required to take full advantage of the relatively thin glass sections for good tracking of ambient temperatures. A modified version of the thermal control system utilized on the Magellan telescope primary mirror will provide adequate cooling. This type of system supplies coolant to multiple on-board blowers in the mirror cell. Each blower contains a fan and a heat exchanger supplying conditioned and mildly pressurized air to the mirror cell. The mirror cell then acts as an air plenum which distributes the air through individual nozzles to each honeycomb cell of the mirror. Unlike previous systems, each LSST blower assembly will incorporate individual air temperature and air flow control systems. Since air can be more accurately heated than cooled, the air will be initially slightly overcooled and then reheated electrically to match the ambient air temperature. Based on thermal sensors in the mirror, the optimum cooling air flow rate to balance mirror thermal distortion and mirror seeing will be determined and enforced by the variable speed fans on the blower assemblies. To further equalize the cooling throughout the mirror, the coolant flow system has also been designed to provide inherently equal coolant flow to each blower assembly.

The Gemini Planet Imager (GPi) is an instrument that will mount to either of two nominally identical Telescopes, Gemini North in Hawaii and Gemini South in Chile, to perform direct imaging and spectroscopy of extra-solar planets. This 2,000-kg instrument has stringent mass, center-of-gravity, flexure, and power constraints. The Flexure Sensitive Structure (FSS) supports the main opto-mechanical sub-systems of the GPi which work in series to process and analyse the telescope optical beam. The opto-mechanical sub-systems within the FSS are sensitive to mechanical vibrations, and passive damping strategies were considered to mitigate image jitter. Based on analysis with the system finite element model (FEM) of the GPi, an array of 1-kg tuned mass dampers (TMDs) was identified as an efficient approach to damp the first two FSS flexural modes which are the main sources of jitter. It is estimated that 5% of critical damping can be added to each of these modes with the addition of 23 kg of TMD mass. This estimate is based on installing TMD units on the FSS structural members. TMD mass can be reduced by nearly 50% if the units can be installed on the opto-mechanical sub-systems within the FSS with the highest modal displacements. This paper describes the structural design and vibration response of the FSS, modal test results, and plans for implementation of the TMDs. Modal measurements of the FSS structure were made to validate the FEM and to assess the viability of TMDs for reducing jitter. The test configuration differed from the operational one because some payloads were not present and the structure was mounted to a flexible base. However, this test was valuable for understanding the primary modes that will be addressed with the TMDs and measuring the effective mass of these modes.

Associated to tracking capabilities, the main axes control system of the E-ELT is the first correcting system in the chain of control loops for reducing the image motion (tip/tilt) caused by perturbations on the telescope. The main objective of the closed-loop performance analysis of the axes is to evaluate the trade offs for the choice of control system hardware, i.e. specification and location of the motors and sensors (encoders/tachometers). In addition, it defines the design constraints and requirements (actuator stroke and bandwidth) of other correcting systems in the chain: the field stabilization (M5 unit) and adaptive deformable mirror (M4 unit). In this paper the main axes control analysis of E-ELT is presented and the performance of telescope in face of external perturbations such as wind and imperfections of the drive (cogging/ripple) and sensing (noise) systems is evaluated. The performance metric is the wavefront error at the focal plane which is derived from the mechanical motion of the telescope's optical elements together with their respective optical sensitivities.

Hexapods are finding increased use in telescope applications for positioning large payloads. Engineers from The University of Texas at Austin have been working with engineers from ADS International to develop large, high force, highly precise and controllable hexapod actuators for use on the Wide Field Upgrade (WFU) as part of the Hobby Eberly Telescope Dark Energy Experiment (HETDEX)^‡. These actuators are installed in a hexapod arrangement, supporting the 3000+ kg instrument payload which includes the Wide Field Corrector (WFC), support structure, and other optical/electronic components. In addition to force capability, the actuators need to meet the tracking speed (pointing) requirements for accuracy and the slewing speed (rewind) requirements, allowing as many observations in one night as possible. The hexapod actuator stroke (retraction and extension) was very closely monitored during the design phase to make sure all of the science requirements could be met, while minimizing the risk of damaging the WFC optical hardware in the unlikely event of a hexapod actuator or controller failure. This paper discusses the design trade-offs between stiffness, safety, back-drivability, accuracy, and leading to selection of the motor, high ratio worm gear, roller screw, coupling, end mounts, and other key components.

The Magellan Baade and Clay telescopes regularly produce images of ~0.5" in natural seeing. We review efforts to improve collimation, active optics response, and telescope guiding and pointing to optimize the performance of the telescopes. Procedures have been developed to monitor and analyze image quality delivered by the imaging science instruments. Improved models have been developed to correct for flexure of the telescope and primary mirror under gravity loading. Collimation has been improved using a "two-probe" Shack-Hartman technique to measure field aberrations. Field acquisition performance has been improved by implementing an open loop model for the primary mirror control. Telescope pointing has been improved by regular monitoring and adjustments to improve acquisition times.

A 4-mirror prime focus corrector is under development to provide seeing-limited images for the 10-m aperture Hobby- Eberly Telescope (HET) over a 22 arcminute wide field of view. The HET uses an 11-m fixed elevation segmented spherical primary mirror, with pointing and tracking performed by moving the prime focus instrument package (PFIP) such that it rotates about the virtual center of curvature of the spherical primary mirror. The images created by the spherical primary mirror are aberrated with 13 arcmin diameter point spread function. The University of Arizona is developing the 4-mirror wide field corrector to compensate the aberrations from the primary mirror and present seeing limited imaged to the pickoffs for the fiber-fed spectrographs. The requirements for this system pose several challenges, including optical fabrication of the aspheric mirrors, system alignment, and operational mechanical stability.

The NASA Infrared Telescope Facility is engaged in a long-term program to improve the image quality of the telescope. One element of the program is to minimize the static aberrations. The largest static aberration is spherical aberration, although aberrations caused by zonal polishing rings and support-pad print-through on the primary mirror are also significant. To correct these static wave front errors, a new secondary mirror is being fabricated with a custom, phase compensating surface. Since the as-built optical specifications for the IRTF mirrors have been lost, a configurable multimode instrument was fabricated for use at both the prime and Cassegrain foci to characterize the primary mirror and to measure the wave front errors at both foci. The instrument modes include a focal plane camera, a knife-edge tester, a pupil viewer, a Hartmann wave front sensor, a calibrator, and an on-axis guider. Test results from the prime focus show that the primary mirror has an incorrect conic surface and is poorly supported, which results in a fixed amount of spherical aberration and variable amounts of astigmatism, coma, and trefoil. Cassegrain focal plane results show that the original secondary mirror mount system also induces aberrations. Two new secondary mirrors have been made and at least one of the mirrors will have a custom surface, using ion beam polishing methods, to correct these static aberrations. An analysis is presently underway to determine the optimum compensating surface to be applied by ion beam polishing.

Cerro Las Campanas located at Las Campanas Observatory (LCO) in Chile has been selected as the site for the Giant Magellan Telescope. We report results obtained since the commencement, in 2005, of a systematic site testing survey of potential GMT sites at LCO. Meteorological (cloud cover, temperature, pressure, wind, and humidity) and DIMM seeing data have been obtained at three potential sites, and are compared with identical data taken at the site of the twin Magellan 6.5m telescopes. In addition, measurements of the turbulence profile of the free-atmosphere above LCO have been collected with a MASS/DIMM. Furthermore, we consider photometric quality, light pollution, and precipitable water vapor (PWV). LCO, and Co. Las Campanas in particular, have dark skies, little or no risk of future light pollution, excellent seeing, moderate winds, PWV adequate for mid-IR astronomy during a reasonable fraction of the nights, and a high fraction of clear nights overall. Finally, Co. Las Campanas meets or exceeds all the defined science requirements.

In support of characterization of potential sites for the European Extremely Large Telescope (E-ELT) the European Southern Observatory (ESO), the Institute for Space Imaging Science (ISIS) and the astrometeorology group of the Universidad Valparaiso have jointly established an improved understanding of atmospheric precipitable water vapour (PWV) above ESO's La Silla Paranal Observatory. In a first step, 8 years worth of high resolution near-IR spectra taken with VLT-UVES have been statistically analysed to reconstruct the PWV history above Paranal. To this end a radiative transfer model of Earth's atmosphere (BTRAM) developed by ISIS has been used. A median PWV of 2.1 mm is found for Paranal based on UVES data covering the period 2001-2008. Furthermore we conclude that Paranal can serve as a reference site for Northern Chile due to the stable atmospheric conditions in the region. The median offset between Paranal and Armazones is derived to be 0.3 mm, but local arbitrary variations of a few tenths of a mm between the sites have been found by measurement. In order to better understand the systematics involved two dedicated campaigns were conducted in August and November 2009. Several methods for determining the water column were employed, including radiosonde launches, continuous measurements by infrared radiometer, and VLT instruments operating at various wavelengths: CRIRES, UVES, VISIR and X-shooter. In a first for astronomical instruments all methods have been evaluated with respect to the radiosondes, the established standard in atmospheric research. Agreement between the radiosondes and the IR radiometer (IRMA) is excellent while all other astronomical methods covering a wavelength range from 700 - 20000 nm have also been successfully validated in a quantitative manner. All available observations were compared to satellite estimates of water vapour above the observatory in an attempt to ground-truth the satellite data. GOES can successfully be used for site evaluation in a purely statistical approach since agreement with the radiosondes is very good on average. For use as an operational tool at an observatory GOES data are much less suited because of significant deviations depending on atmospheric conditions. We propose to routinely monitor PWV at the VLT and to use it as an operational constraint to guide scheduling of IR observations at Paranal. For the E-ELT we find that a stand-alone high time resolution PWV monitor will be essential for optimizing the scientific output.

Remote turbulence sensing in the first 100m above ground using lunar scintillation has revealed that the seeing measured by regular site monitors can be over-estimated. This explains the well-known discrepancy between the VLT image quality and the seeing measured by the DIMM at Paranal. The concept of "site seeing" needs to be critically reviewed, considering strong dependence of this parameter on the height of site monitors and on the local turbulence in their immediate vicinity. Higher resolution of ground-based telescopes can be reached if we accept that the natural seeing can be better than shown by the DIMMs and that the contribution of telescope and its environment to the seeing can be significant on nights with superb conditions. This is particularly relevant to the wide-angle optical and IR telescopes which do not rely on adaptive optics. Eventually, a wide-angle adaptive optics will remove local and instrumental distortions and will deliver images truly limited by the atmosphere.

In the framework of the E-ELT project a prospecting campaign was launched by the ESO to select the site that will host the next generation of optical telescopes of 42 m diameter. Moroccan Anti-Atlas (Jbel Aklim) was selected as well as other sites (ORM, Ventarrones and Macon) to be a possible potential location that will house the E-ELT. In this paper we first present the reasons for the choice of Jbel Aklim as a E-ELT candidate through various exploration campaigns that we have achieved. The second part concerns description of instruments used. Finally we will present the preliminary results of the meteorological and MASS-DIMM measurements.

A characterization of the optical turbulence vertical distribution and all the main integrated astroclimatic parameters derived from the C²_N and the wind speed profiles above Mt. Graham is presented. The statistic includes measurements related to 43 nights done with a Generalized Scidar (GS) used in standard configuration with a vertical resolution of ~1 km on the whole 20-22 km and with the new technique (HVR-GS) in the first kilometer. The latter achieves a resolution of ~ 20-30 m in this region of the atmosphere. Measurements done in different periods of the year permit us to provide a seasonal variation analysis of the C²_N. A discretized distribution of the typical C²_N profiles useful for the Ground Layer Adaptive Optics (GLAO) simulations is provided and a specific analysis for the LBT Laser Guide Star system ARGOS case is done including the calculation of the 'gray zones' for J, H and K bands. Mt. Graham confirms to be an excellent site with median values of the seeing without dome contribution equal to 0.72", the isoplanatic angle equal to 2.5" and the wavefront coherence time equal to 4.8 msec. We provide a cumulative distribution of the percentage of turbulence developed below H* where H* is included in the (0,1 km) range. We find that 50% of the whole turbulence develops in the first 80 m from the ground. The turbulence decreasing rate is very similar to what has been observed above Mauna Kea.

Atmospheric optical turbulence is the main driver of wavefront distortions which affect optical telescope performance. Therefore, many techniques have been developed to measure the optical turbulence strength along the line of sight. Based on data collected with the MASS (Multi Aperture Scintillation Sensor), we show that a large sample of such measurements can be used to assess the average three dimensional turbulence distribution above ground. The use of, and a more sophisticated instrumental setup for, such turbulence tomography will be discussed.

As part of a program to measure and evaluate atmospheric turbulence on mountains at the most northerly tip of North America, we have deployed two SODARs and a lunar scintillometer at the Polar Environment Atmospheric Research Lab (PEARL) located on a 600m-high ridge near Eureka on Ellesmere Island, at 80° latitude. This paper discusses the program and presents a summary of ground-layer turbulence and seeing measurements from the 2009-10 observing season.

The high altitude Antarctic sites of Dome A and the South Pole offer intriguing locations for future large scale optical astronomical Observatories. The Gattini project was created to measure the optical sky brightness, large area cloud cover and aurora of the winter-time sky above such high altitude Antarctic sites. The Gattini- DomeA camera was installed on the PLATO instrument module as part of the Chinese-led traverse to the highest point on the Antarctic plateau in January 2008. This single automated wide field camera contains a suite of Bessel photometric filters (B, V, R) and a long-pass red filter for the detection and monitoring of OH emission. We have in hand one complete winter-time dataset (2009) from the camera that was recently returned in April 2010. The Gattini-South Pole UV camera is a wide-field optical camera that in 2011 will measure for the first time the UV properties of the winter-time sky above the South Pole dark sector. This unique dataset will consist of frequent images taken in both broadband U and B filters in addition to high resolution (R~5000) long slit spectroscopy over a narrow bandwidth of the central field. The camera is a proof of concept for the 2m-class Antarctic Cosmic Web Imager telescope, a dedicated experiment to directly detect and map the redshifted lyman alpha fluorescence or Cosmic Web emission we believe possible due to the unique geographical qualities of the site. We present the current status of both projects.