Design considerations for CELT adaptive optics

California Institute of Technology and University of California have begun conceptual design studies for a new telescope for astronomical research at visible and infrared wavelengths. The California Extremely Large Telescope (CELT) is currently envisioned as a filled-aperture, steerable, segmented telescope of approximately 30 m diameter. The key to satisfying many of the science goals of this observatory is the availability of diffraction-limited wavefront control. We describe potential observing modes of CELT, including a discussion of the several major outstanding AO system architectural design issues to be resolved prior to the initiation of the detailed design of the adaptive optics capability

Weather Research and Forecasting Model Wind Sensitivity Study at Edwards Air Force Base, CA

This abstract describes work that will be done by the Applied Meteorology Unit (AMU) in assessing the success of different model configurations in predicting "wind cycling" cases at Edwards Air Force Base, CA (EAFB), in which the wind speeds and directions oscillate among towers near the EAFB runway. The Weather Research and Forecasting (WRF) model allows users to choose among two dynamical cores - the Advanced Research WRF (ARW) and the Non-hydrostatic Mesoscale Model (NMM). There are also data assimilation analysis packages available for the initialization of the WRF model - the Local Analysis and Prediction System (LAPS) and the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS). Having a series of initialization options and WRF cores, as well as many options within each core, creates challenges for local forecasters, such as determining which configuration options are best to address specific forecast concerns. The goal of this project is to assess the different configurations available and determine which configuration will best predict surface wind speed and direction at EAFB

Integrated Laboratory Demonstrations of Multi-Object Adaptive Optics on a Simulated 10-Meter Telescope at Visible Wavelengths

One important frontier for astronomical adaptive optics (AO) involves methods such as Multi-Object AO and Multi-Conjugate AO that have the potential to give a significantly larger field of view than conventional AO techniques. A second key emphasis over the next decade will be to push astronomical AO to visible wavelengths. We have conducted the first laboratory simulations of wide-field, laser guide star adaptive optics at visible wavelengths on a 10-meter-class telescope. These experiments, utilizing the UCO/Lick Observatory's Multi-Object / Laser Tomography Adaptive Optics (MOAO/LTAO) testbed, demonstrate new techniques in wavefront sensing and control that are crucial to future on-sky MOAO systems. We (1) test and confirm the feasibility of highly accurate atmospheric tomography with laser guide stars, (2) demonstrate key innovations allowing open-loop operation of Shack-Hartmann wavefront sensors (with errors of ~30 nm) as will be needed for MOAO, and (3) build a complete error budget model describing system performance. The AO system maintains a performance of 32.4% Strehl on-axis, with 24.5% and 22.6% at 10" and 15", respectively, at a science wavelength of 710 nm (R-band) over the equivalent of 0.8 seconds of simulation. The MOAO-corrected field of view is ~25 times larger in area than that limited by anisoplanatism at R-band. Our error budget is composed of terms verified through independent, empirical experiments. Error terms arising from calibration inaccuracies and optical drift are comparable in magnitude to traditional terms like fitting error and tomographic error. This makes a strong case for implementing additional calibration facilities in future AO systems, including accelerometers on powered optics, 3D turbulators, telescope and LGS simulators, and external calibration ports for deformable mirrors.Comment: 29 pages, 11 figures, submitted to PAS

The Infrared Imaging Spectrograph (IRIS) for TMT: the atmospheric dispersion corrector

We present a conceptual design for the atmospheric dispersion corrector (ADC) for TMT's Infrared Imaging Spectrograph (IRIS). The severe requirements of this ADC are reviewed, as are limitations to observing caused by uncorrectable atmospheric effects. The requirement of residual dispersion less than 1 milliarcsecond can be met with certain glass combinations. The design decisions are discussed and the performance of the design ADC is described. Alternative options and their performance tradeoffs are also presented.Comment: SPIE Astronomical Instrumentation 201

The infrared imaging spectrograph (IRIS) for TMT: spectrograph design

The Infra-Red Imaging Spectrograph (IRIS) is one of the three first light instruments for the Thirty Meter Telescope (TMT) and is the only one to directly sample the diffraction limit. The instrument consists of a parallel imager and off-axis Integral Field Spectrograph (IFS) for optimum use of the near infrared (0.84um-2.4um) Adaptive Optics corrected focal surface. We present an overview of the IRIS spectrograph that is designed to probe a range of scientific targets from the dynamics and morphology of high-z galaxies to studying the atmospheres and surfaces of solar system objects, the latter requiring a narrow field and high Strehl performance. The IRIS spectrograph is a hybrid system consisting of two state of the art IFS technologies providing four plate scales (4mas, 9mas, 25mas, 50mas spaxel sizes). We present the design of the unique hybrid system that combines the power of a lenslet spectrograph and image slicer spectrograph in a configuration where major hardware is shared. The result is a powerful yet economical solution to what would otherwise require two separate 30m-class instruments.Comment: 15 pages, 11 figure

Optical design for the narrow field infrared adaptive optics system (NFIRAOS) petite on the thirty meter telescope

We describe an exploratory optical design for the Narrow Field InfraRed Adaptive Optics (AO) System (NFIRAOS) Petite, a proposed adaptive optics system for the Thirty Meter Telescope Project. NFIRAOS will feed infrared spectrograph and wide-field imaging instruments with a diffraction limited beam. The adaptive optics system will require multi-guidestar tomographic wavefront sensing (WFS) and multi-conjugate AO correction. The NFIRAOS Petite design specifications include two small 60 mm diameter deformable mirrors (DM's) used in a woofer/tweeter or multiconjugate arrangement. At least one DM would be a micro-electromechanical system (MEMS) DM. The AO system would correct a 10 to 30 arcsec diameter science field as well as laser guide stars (LGS's) located within a 60 arcsec diameter field and low-order or tip/tilt natural guide stars (NGS's) within a 60 arcsec diameter field. The WFS's are located downstream of the DM's so that they can be operated in true closed-loop, which is not necessarily a given in extremely large telescope adaptive optics design. The WFS's include adjustable corrector elements which correct the static aberrations of the AO relay due to field position and LGS distance height

Initial concepts for CELT adaptive optics

The California Extremely Large Telescope (CELT) project has recently completed a 12-month conceptual design phase that has investigated major technology challenges in a number of Observatory subsystems, including adaptive optics (AO). The goal of this effort was not to adopt one or more specific AO architectures. Rather, it was to investigate the feasibility of adaptive optics correction of a 30-meter diameter telescope and to suggest realistic cost ceilings for various adaptive optics capabilities. We present here the key design issues uncovered during conceptual design and present two non-exclusive "baseline" adaptive optics concepts that are expected to be further developed during the following preliminary design phase. Further analysis, detailed engineering trade studies, and certain laboratory and telescope experiments must be performed, and key component technology prototypes demonstrated, prior to adopting one or more adaptive optics systems architectures for realization

Christianity and Hinduism: An Annotated Bibliography

No abstract availabl