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Laser guide stars have increased the utility of adaptive optics systems by expanding the number of observable objects. The most common type of laser excites sodium in the mesosphere, and mesospheric sodium density is key to the performance of the laser. While a variety of observatories have conducted studies of the mesospheric sodium density, there are no published studies from Hawaii, which is home to some of the largest telescopes in the world. This paper presents mesospheric sodium densities measured by the University of Illinois lidar for 165 hr spanning 25 nights over 3 years. The mean sodium column density is 4.3 × 109 ± 0.2 × 109 cm–2, with a seasonal peak in the winter, as found at many other sites. The variations in a given night can be as high as the seasonal variation. We predict the average photon returns for the 15 W Keck II laser and a proposed 50 W laser at the Advanced Electro-Optical System 3.6 m telescope for the observed sodium abundances.

The Keck Interferometer Nuller (KIN) is one of the major scientific and technical precursors to the Terrestrial Planet Finder Interferometer (TPF-I) mission. KIN's primary objective is to measure the level of exo-zodiacal mid-infrared emission around nearby main sequence stars, which requires deep broad-band nulling of astronomical sources of a few Janskys at 10 microns. A number of new capabilities are needed in order to reach that goal with the Keck telescopes: mid-infrared coherent recombination, interferometric operation in 'split pupil' mode, N-band optical path stabilization using K-band fringe tracking and internal metrology, and eventually, active atmospheric dispersion correction. We report here on the progress made implementing these new functionalities, and discuss the initial levels of extinction achieved on the sky.

HD 8673 hosts a massive exoplanet in a highly eccentric orbit (e=0.723). Based on two epochs of speckle interferometry a previous publication identified a candidate stellar companion. We observed HD 8673 multiple times with the 10 m Keck II telescope, the 5 m Hale telescope, the 3.63 m AEOS telescope and the 1.5m Palomar telescope in a variety of filters with the aim of confirming and characterizing the stellar companion. We did not detect the candidate companion, which we now conclude was a false detection, but we did detect a fainter companion. We collected astrometry and photometry of the companion on six epochs in a variety of filters. The measured differential photometry enabled us to determine that the companion is an early M dwarf with a mass estimate of 0.33-0.45 M?. The companion has a projected separation of 10 AU, which is one of the smallest projected separations of an exoplanet host binary system. Based on the limited astrometry collected, we are able to constrain the orbit of the stellar companion to a semi-major axis of 35{60 AU, an eccentricity ? 0.5 and an inclination of 75{85?. The stellar companion has likely strongly in uenced the orbit of the exoplanet and quite possibly explains its high eccentricity., Comment: Accepted to the Astronomical Journal, 6 Pages, 5 Figures

There is great interest in the adaptive optics (AO) science community to overcome the limitations imposed by incomplete knowledge of the point spread function (PSF). To address this limitation a program has been initiated at the W. M. Keck Observatory (WMKO) to demonstrate PSF determination for observations obtained with Keck AO science instruments. This paper aims to give a broad view of the progress achieved in this area. The concept and the implementation are briefly described. The results from on-sky on-axis NGS AO measurements using the NIRC2 science instrument are presented. On-sky performance of the technique is illustrated by comparing the reconstructed PSFs to NIRC2 PSFs. Accuracy of the reconstructed PSFs in terms of Strehl ratio and FWHM are discussed. Science cases for the first phase of science verification have been identified. More technical details of the program are presented elsewhere in the conference.

The Keck Interferometer (KI) combined the two 10 m W. M. Keck Observatory telescopes on Mauna Kea, Hawaii, as a long-baseline near- and mid-infrared interferometer. Funded by NASA, it operated from 2001 until 2012. KI used adaptive optics on the two Keck telescopes to correct the individual wavefronts, as well as active fringe tracking in all modes for path-length control, including the implementation of cophasing to provide long coherent integration times. KI implemented high sensitivity fringe-visibility measurements at H (1.6 μm), K (2.2 μm), and L (3.8 μm) bands, and nulling measurements at N band (10 μm), which were used to address a broad range of science topics. Supporting these capabilities was an extensive interferometer infrastructure and unique instrumentation, including some additional functionality added as part of the NSF-funded ASTRA program. This paper provides an overview of the instrument architecture and some of the key design and implementation decisions, as well as a description of all of the key elements and their configuration at the end of the project. The objective is to provide a view of KI as an integrated system, and to provide adequate technical detail to assess the implementation. Included is a discussion of the operational aspects of the system, as well as of the achieved system performance. Finally, details on V^2 calibration in the presence of detector nonlinearities as applied in the data pipeline are provided.

Anisoplanatism is a primary source of photometric and astrometric error in single-conjugate adaptive optics. We present initial results of a project to model the off-axis optical transfer function in the adaptive optics system at the Keck II telescope. The model currently accounts for the effects of atmospheric anisoplanatism in natural guide star observations. The model for the atmospheric contribution to the anisoplanatic transfer function uses contemporaneous MASS/ DIMM measurements. Here we present the results of a validation campaign using observations of naturally guided visual binary stars under varying conditions, parameterized by the r0 and θ0 parameters of the C2n atmospheric turbulence profile. We are working to construct a model of the instrumental field-dependent aberrations in the NIRC2 camera using an artificial source in the Nasmyth focal plane. We also discuss our plans to extend the work to laser guide star operation. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

We report on the preliminary design of W.M. Keck Observatory's (WMKO's) next-generation adaptive optics (NGAO) facility. This facility is designed to address key science questions including understanding the formation and evolution of today's galaxies, measuring dark matter in our galaxy and beyond, testing the theory of general relativity in the Galactic Center, understanding the formation of planetary systems around nearby stars, and exploring the origins of our own solar system. The requirements derived from these science questions have resulted in NGAO being designed to have near diffraction-limited performance in the near-IR (K-Strehl ~ 80%) over narrow fields (< 30" diameter) with modest correction down to ~ 700 nm, high sky coverage, improved sensitivity and contrast and improved photometric and astrometric accuracy. The resultant key design features include multi-laser tomography to measure the wavefront and correct for the cone effect, open loop AO-corrected near-IR tip-tilt sensors with MEMS deformable mirrors (DMs) for high sky coverage, a high order MEMS DM for the correction of atmospheric and telescope static errors to support high Strehls and high contrast companion sensitivity, point spread function (PSF) calibration to benefit quantitative astronomy, a cooled science path to reduce thermal background, and a high-efficiency science instrument providing imaging and integral field spectroscopy.

A laser guide star (LGS) adaptive optics (AO) system generally requires additional tip/tilt information derived using a natural guide star (NGS), while multi-LGS systems will benefit from measurement of additional low-order wavefront modes using one or more NGS's. If we use AO sharpened NGS's, we can improve both the measurement accuracy and accessible sky fraction while also minimizing the observational overhead of faint NGS acquisition. Multi-object adaptive optics (MOAO) sharpening of NGS is possible where a good estimate of the NGS wavefront can be made, for example where tomographic wavefront information is available. We describe a new approach for high Strehl ratio sharpening, based on additional patrolling laser beacons, to eliminate generalized anisoplanatism and minimize tomography error in the NGS direction.

The W. M. Keck Observatory is currently engaged in the conceptual design of a powerful new adaptive optics (AO) science capability providing precision AO correction in the near infrared (NIR) and visible and faint object multiplexed integral field spectroscopy. In this poster, we present the conceptual design of the Science Operations for this Next Generation Adaptive Optics (NGAO) facility. We summarize the main requirements for science operations resulting from the science cases and the Observatory requirements. We give an overview of the science operation paradigm and design that will meet these requirements. We then illustrate the pre-observing, observing and post-observing interfaces by looking into various observing scenarios. We conclude by briefly outlining the project milestones.

The impact of segment vibration on the performance of adaptive optics at Keck Observatory was modeled. Errors after correction are significant but comparable to other errors in future adaptive optics systems.

We present the final results of the injection tests of adaptive optics corrected light into single mode fibers, conducted at Canada-France-Hawaii Telescope, W.M. Keck Observatory and Gemini North Observatory, in the prospect of 'OHANA Phase I (preparatory phase). We emphasize on the impact of the results on both the 'OHANA Phase II (interferometric demonstration phase) sensitivity and observational protocol and the behavior of the different adaptive optics.

This paper describes the upgrades to the Keck II Adaptive Optics (K2 AO) system needed for laser guide star observing. The upgrade, including integration with the laser, is scheduled for completion in the winter of 2003. This upgrade includes the addition of a Low Bandwidth Wavefront Sensor (LBWFS) measuring focus and higher order terms, and a Lawrence Livermore National Lab quad-lens avalanche photodiode detector which monitors tip/tilt. Both observe a dim natural guide star. LBWFS corrections are applied as corrections to the high bandwidth wavefront sensor, which is observing the laser beacon. These subsystems drive focus stages, a deformable mirror, a tip/tilt mirror for the incoming starlight, and a tip/tilt mirror for pointing the propagating laser beam. Taken together, and in concert with the rest of the components of the K2 AO system, they provide the tools and the means to observe the universe as never before.

A laser guided adaptive optics system called UnISIS -- University of Illinois Seeing Improvement System -- has been commissioned at the Mt. Wilson 2.5-m Telescope. The UnISIS laser guide star is created via Rayleigh scattering of 351 nm photons from a 30 W excimer laser. The laser guide star is focused at an altitude of 20 km above msl. The UnISIS adaptive optics system sits at the fixed f/30 Coude focus of the 2.5-m telescope while the 30 W excimer laser sits on the observatory ground floor. The collimated laser beam is projected first into the Coude room where it is converted to f/30 and projected into the sky off the 2.5-m primary mirror. We describe the practical experience gained in installing and commissioning UnISIS, and we present simulations of the expected system performance based on the characteristic C n 2 distribution above Mt. Wilson.

The relative wander in the positions of the laser beacons in a multiple beacon system limits the accuracy to which the wavefront can be measured. We describe the design of an experiment to test methods for reducing laser beacon wander. The system employs an excimer laser producing Rayleigh guide stars at an altitude of 10 km mounted at the Coude focus of the Mt. Laguna 1 m telescope. The experimental tests are based on simultaneously creating two guide stars and measuring their apparent differential motion in a set of projection and detection schemes that includes: full aperture broadcast, partial aperture broadcast, full aperture reception, and partial aperture reception.

International audience; Because of an error at the Press, the received date for this paper was incorrectly given as 2004 January 5. The correct received date is 2004 December 5. The Press sincerely regrets this error.