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We present high resolution (~0.1"), very high Strehl ratio (0.97+-0.03) mid-infrared (IR) adaptive optics (AO) images of the AGB star RV Boo utilizing the MMT adaptive secondary AO system. RV Boo was observed at a number of wavelengths over two epochs (9.8 um in May 2003, 8.8, 9.8 and 11.7 um in February 2004) and appeared slightly extended at all wavelengths. While the extension is very slight at 8.8 and 11.7 um data, the extension is somewhat more pronounced at 9.8 um. With such high Strehls we can achieve super-resolutions of 0.1" by deconvolving RV Boo with a point-spread function (PSF) derived from an unresolved star. We tentatively resolve RV Boo into a 0.16" FWHM extension at a position angle of 120 degrees. At a distance of 390(+250)(-100) pc, this corresponds to a FWHM of 60(+40)(-15) AU. We measure a total flux at 9.8 um of 145+-24 Jy for the disk and star. Based on a dust thermal emission model for the observed IR spectral energy distribution and the 9.8 um AO image, we derive a disk dust mass of 1.6x10^-6 Msun and an inclination of 30 to 45 degrees from edge-on. We discuss whether the dust disk observed around RV Boo is an example of the early stages in the formation of asymmetric structure in planetary nebula.

We present the results of mid-infrared nulling interferometric observations of the main-sequence star alpha Lyr (Vega) using the 6.5 m MMT with its adaptive secondary mirror. From the observations at 10.6 microns, we find that there is no resolved emission from the circumstellar environment (at separations greater than 0.8 AU) above 2.1% (3 sigma limit) of the level of the stellar photospheric emission. Thus, we are able to place an upper limit on the density of dust in the inner system of 650 times that of our own solar system's zodiacal cloud. This limit is roughly 2.8 times better than those determined with photometric excess observations such as those by IRAS. Comparison with far-infrared observations by IRAS shows that the density of warm dust in the inner system (< 30 AU) is significantly lower than cold dust at larger separations. We consider two scenarios for grain removal, the sublimation of ice grains and the presence of a planetary mass "sweeper." We find that if sublimation of ice grains is the only removal process, a large fraction (> 80%) of the material in the outer system is ice., 11 pages, 1 figure, Accepted to The Astrophysical Journal Letters

We present the first scientific images obtained with a deformable secondary mirror adaptive optics (AO) system. We utilized the 6.5 m Multiple Mirror Telescope adaptive optics system to produce high-resolution (FWHM ¼ 0>07) near-infrared (1.6 lm) images of the young (� 1 Myr) Orion Trapezium � 1 Ori cluster members. A combination of high spatial resolution and high signal-to-noise ratio allowed the positions of these stars to be measured to within � 0>003 accuracies. We also present slightly lower resolution (FWHM � 0>085) images from Gemini with the Hokupa‘a AO system as well. Including previous speckle data from Weigelt et al., we analyze a 6 yr baseline of high-resolution observations of this cluster. Over this baseline we are sensitive to relative proper motions of only � 0>002 yr � 1 (4.2 km s � 1 at 450 pc). At such sensitivities we detect orbital motion in the very tight � 1 Ori B2-B3 (52 AU separation) and � 1 Ori A1-A2 (94 AU separation) systems. The relative velocity in the � 1 Ori B2-B3 system is 4:2 � 2: 1k m s � 1 . We observe 16:5 � 5: 7k m s � 1 of relative motion in the � 1 Ori A1-A2 system. These velocities are consistent with those independently observed by Schertl et al. with speckle interferometry, giving us confidence that these very small (� 0>002 yr � 1 ) orbital motions are real. All five members of the � 1 Ori B system appear likely gravitationally bound (B2-B3 is moving at � 1.4 km s � 1 in the plane of the sky with respect to B1, where Vesc � 6k m s � 1 for the B group). The very lowest mass member of the � 1 Ori B system (B4) has K 0 � 11:66 and an estimated mass of � 0.2 M� . Very little motion (4 � 15 km s � 1 ) of B4 was detected with respect to B1 or B2; hence, B4 is possibly part of the � 1 Ori B group. We suspect that if this very low mass member is physically associated, it most likely is in an unstable (nonhierarchical) orbital position and will soon be ejected from the group. The � 1 Ori B system appears to be a good example of a star formation ‘‘ minicluster,’’ which may eject the lowest mass members of the cluster in the near future. This ‘‘ ejection ’’ process could play a major role in the formation of low-mass stars and brown dwarfs. Subject headings: binaries: general — instrumentation: adaptive optics — stars: evolution — stars: formation — stars: low-mass, brown dwarfs On-line material: color figures

We utilized the MMT's unique deformable secondary adaptive optics system to produce high-resolution (FWHM=0.3"), very high Strehl mid-infrared (9.8, 11.7 & 18 micron) images of the post-AGB star AC Her. The very high (98+/-2%) Strehls achieved with Mid-IR AO led naturally to an ultra-stable PSF independent of airmass, seeing, or location on the sky. We find no significant difference between AC Her's morphology and our unresolved PSF calibration stars (mu UMa & alpha Her) at 9.8, 11.7, & 18 microns. Our current observations do not confirm any extended Mid-IR structure around AC Her. These observations are in conflict with previously reported Keck (seeing-limited) 11.7 and 18 micron images which suggested the presence of a resolved ~0.6" edge-on circumbinary disk. We conclude that AC Her has no extended Mid-IR structure on scales greater than 0.2" (R

An adaptive optics system is being built for the 6.5 m Multiple Mirror Telescope (MMT) conversion on Mount Hopkins for diffraction-limited observations in the near-infrared. At the heart of the system is a deformable secondary mirror which introduces corrections to the optical wavefront. By compensating these errors at the telescope's secondary, the system has been optimized for low thermal emissivity and high photon throughput. The scientific productivity of the facility will thereby be enhanced in comparison with a telescope equipped with more conventional adaptive optics. The Large Binocular Telescope under construction on Mount Graham will also use adaptive secondary mirrors. This paper explores the benefit to both facilities in terms of the integration time required to achieve a given signal-to-noise ratio. The gain is found to be substantial in the photometric bands K, L, M, and N.

Laser beams directed into the sky from astronomical observatories to generate guide beacons for adaptive optics image-sharpening systems are a potential hazard to aircraft. Detection systems are needed to sense aircraft and interrupt the laser beam to prevent accidental illumination. We describe here a system designed for this task. A computer examines CCD images of the sky over a wide field of view and uses a motion detection algorithm to find tracks made by aircraft lights. The results of tests, conducted with simultaneous radar coverage from Tucson International Airport, are reported. A test with an actual laser beacon at the Multiple Mirror Telescope in which Mars was used as a simulated aircraft is also described.

Adaptive optics with a sodium resonance laser guide star was used at the Multiple Mirror Telescope (MMT) in 1996 April to image the core of the globular cluster M13 (NGC 6205). A 23'' field was recorded in the Ks band with image resolution of 051, when the uncorrected resolution was 072. Global tilt, not sensed by the laser, was measured from the image motion of a star 35'' from the center of the field. Despite this separation, the star profiles do not vary significantly across the image. Many more stars fainter than Ks = 17.5 can be identified in the corrected image. The 05 imaging capability demonstrated here, though not reaching the performance of existing faster, higher order systems with natural star wave-front sensors, is significant because it can be generally realized for very faint objects under normal observing conditions. This characteristic will carry over to higher order laser-based systems, making them very powerful. Our current 05 resolution is much larger than the diffraction limit for the present MMT array (and its upcoming 6.5 m monolithic replacement) because discontinuities prevent the measurement of phase differences between the array elements. Furthermore, small-scale wave-front aberrations caused by atmospheric and static errors across individual mirrors were not corrected. But our system, by its simultaneous correction of differential slopes derived from the laser beacon and global tilt from the natural guide star, illuminates the principles and sources of error common to all future laser systems.

ARGOS the Advanced Rayleigh guided Ground layer adaptive Optics System for the LBT (Large Binocular Telescope) is built by a German-Italian-American consortium. It will be a seeing reducer correcting the turbulence in the lower atmosphere over a field of 2' radius. In such way we expect to improve the spatial resolution over the seeing of about a factor of two and more and to increase the throughput for spectroscopy accordingly. In its initial implementation, ARGOS will feed the two near-infrared spectrograph and imager - LUCI I and LUCI II. The system consist of six Rayleigh lasers - three per eye of the LBT. The lasers are launched from the back of the adaptive secondary mirror of the LBT. ARGOS has one wavefront sensor unit per primary mirror of the LBT, each of the units with three Shack-Hartmann sensors, which are imaged on one detector. In 2010 and 2011, we already mounted parts of the instrument at the telescope to provide an environment for the main sub-systems. The commissioning of the instrument will start in 2012 in a staged approach. We will give an overview of ARGOS and its goals and report about the status and new challenges we encountered during the building phase. Finally we will give an outlook of the upcoming work, how we will operate it and further possibilities the system enables by design.

A near-infrared adaptive optics system operating at about 50 Hz has been used to control phase errors adaptively between two mirrors of the Multiple Mirror Telescope by stabilizing the position of the interference fringe in the combined unresolved far-field image. The resultant integrated images have angular resolutions of better than 0.1 arcsec and fringe contrasts of more than 0.6. Measurements of wave-front tilt have confirmed the wavelength independence of image motion. These results show that interferometric sensing of phase errors, when combined with a system for sensing the wave-front tilt of the individual telescopes, will provide a means of achieving a stable diffraction-limited focus with segmented telescopes or arrays of telescopes.

A multi-laser adaptive optics system, at the 6.5 m MMT telescope, has been undergoing commissioning in preparation for wide-field, partially corrected as well as narrow-field, diffraction limited science observations in the thermal and near infrared. After several delays due to bad weather, we have successfully closed the full high order ground-layer adaptive optics (GLAO) control loop for the first time in February 2008 using five Rayleigh laser guide stars and a single tilt star. Characterization and automated correction of static aberrations such as non-common path errors were addressed in May 2008. Calibration measurements in preparation for laser tomography adaptive optics (LTAO) operation are planned for the fall of 2008 along with the start of shared-risk GLAO science observations. We present the results of GLAO observations with the PISCES imager, a 1 - 2.5 µm camera with a field of view of 110 arc seconds. The status of the remaining GLAO commissioning work is also reviewed. Finally, we present plans for commissioning work to implement the LTAO operating mode of the system.

IMAGES formed by ground-based telescopes are marred by atmospheric 'seeing9. The plane wavefront from an unresolved star is distorted by continually changing turbulent fluctuations in the air's refractive index. Diffraction-limited performance can in principle be recovered through the methods of adaptive optics, in which the instantaneous wavefront shape is sensed and corrected in real-time by deformable optics that cancel the distortion1,2. The highest resolution will be achieved when this technique is applied to multiple-telescope arrays. For such arrays, the biggest errors caused by seeing at infrared wavelengths are the variations in pathlength and wavefront tilt between array elements. We show here that these errors can be derived by an artificial neural network, given only a pair of simultaneous in-focus and out-of-focus images of a reference star formed at the combined focus of all the array elements. We have optimized a neural network appropriate for 2.2-μm wavelength imaging at the Multiple Mirror Telescope in Arizona. Corrections made by moving the beam-combining mirrors will largely recover the diffraction-limited profile, with a resolution of 0.06 arcsec.

Observational tests of ground layer wavefront recovery have been made in open loop using a constellation of four natural guide stars at the 1.55 m Kuiper telescope in Arizona. Such tests explore the effectiveness of wide-field seeing improvement by correction of low-lying atmospheric turbulence with ground-layer adaptive optics (GLAO). The wavefronts from the four stars were measured simultaneously on a Shack-Hartmann wavefront sensor (WFS). The WFS placed a 5 x 5 array of square subapertures across the pupil of the telescope, allowing for wavefront reconstruction up to the fifth radial Zernike order. We find that the wavefront aberration in each star can be roughly halved by subtracting the average of the wavefronts from the other three stars. Wavefront correction on this basis leads to a reduction in width of the seeing-limited stellar image by up to a factor of 3, with image sharpening effective from the visible to near infrared wavelengths over a field of at least 2 arc minutes. We conclude that GLAO correction will be a valuable tool that can increase resolution and spectrographic throughput across a broad range of seeing-limited observations., 25 pages, 8 figures, to be published in Astrophys. J

Using five independent analytic and Monte Carlo simulation codes, we have studied the performance of wide field ground layer adaptive optics (GLAO), which can use a single, relatively low order deformable mirror to correct the wavefront errors from the lowest altitude turbulence. GLAO concentrates more light from a point source in a smaller area on the science detector, but unlike traditional adaptive optics, images do not become diffraction-limited. Rather the GLAO point spread function (PSF) has the same functional form as a seeing-limited PSF, and can be characterized by familiar performance metrics such as Full-Width Half-Max (FWHM). The FWHM of a GLAO PSF is reduced by 0.1" or more for optical and near-infrared wavelengths over different atmospheric conditions. For the Cerro Pachon atmospheric model this correction is even greater when the image quality is worst, which effectively eliminates "bad-seeing" nights; the best seeing-limited image quality, available only 20% of the time, can be achieved 60 to 80% of the time with GLAO. This concentration of energy in the PSF will reduce required exposure times and improve the efficiency of an observatory up to 30 to 40%. These performance gains are relatively insensitive to a number of trades including the exact field of view of a wide field GLAO system, the conjugate altitude and actuator density of the deformable mirror, and the number and configuration of the guide stars., Comment: 16 pages, 19 figures, accepted for publication in PASP

Adaptive optics to correct current telescopes over wide fields, or future very large telescopes over even narrow fields, will require real-time wavefront measurements made with a constellation of laser beacons. Here we report the first such measurements, made at the 6.5 m MMT with five Rayleigh beacons in a 2 arcmin pentagon. Each beacon is made with a pulsed beam at 532 nm, of 4 W at the exit pupil of the projector. The return is range-gated from 20-29 km and recorded at 53 Hz by a 36-element Shack-Hartmann sensor. Wavefronts derived from the beacons are compared with simultaneous wavefronts obtained for individual natural stars within or near the constellation. Observations were made in seeing averaging 1.0 arcsec with 2/3 of the aberration measured to be from a ground layer of mean height 380 m. Under these conditions, subtraction of the simple instantaneous average of the five beacon wavefronts from the stellar wavefronts yielded a 40% rms reduction in the measured modes of the distortion over a 2 arcmin field. We discuss the use of multiple Rayleigh beacons as an alternative to single sodium beacons on 8 m telescopes, and the impact of the new work on the design of a multi-sodium beacon system for the 25 m Giant Magellan Telescope., Comment: 25 pages, 7 figures, uses aastex.cls, to be published in the Astrophys. J

Use of the highly sensitive Hokupa'a curvature wavefront sensor has allowed for the first time direct adaptive optics (AO) guiding on brown dwarfs and VLM stars (SpT=M7-L2). An initial survey of 9 such objects discovered one 0.15" binary (2MASSJ 1426316+155701). The companion is about half as bright as the primary (Delta K = 0.61+/-0.05$, Delta H = 0.70+/-0.05) and has even redder colors H-K=0.59+/-0.14 than the primary. The blended spectrum of the binary has been previously determined to be M9.0. We modeled a blend of an M8.5 template and a L1-L3 template reproducing a M9.0 spectrum in the case of Delta K = 0.61+/-0.05,Delta H = 0.70\pm0.05$. These spectral types also match the observed H-K colors of each star. Based the previously observed low space motion and $H_{\alpha}$ activity we assign an age of $0.8^{+6.7}_{-0.3} Gyr$. Utilizing this age range and the latest DUSTY models of the Lyon group we assign a photometric distance of $18.8^{+1.44}_{-1.02} pc$ and masses of $M_{A}=0.074^{+0.005}_{-0.011} M_\odot$ and $M_{B}=0.066^{+0.006}_{-0.015} M_\odot$. We therefore estimate a system separation of $2.92_{+0.22}^{-0.16}AU$ and a period of $13.3{+3.18}^{-1.51} yr$ respectively. Hence, 2M1426 is among the smallest separation brown dwarf binaries resolved to date.

High resolution spectroscopy experiments with visible adaptive optics (AO) telescopes at Starfire Optical Range and Mt. Wilson have demonstrated that spectral resolution can be routinely improved by a factor of - 10 over the seeing-limited case with no extra light losses at visible wavelengths. With large CCDs now available, a very wide wavelength range can be covered in a single exposure. In the near future, most large ground-based telescopes will be equipped with powerful A0 systems. Most of these systems are aimed primarily at diffraction-limited operation in the near IR. An exciting new opportunity will thus open up for high resolution IR spectroscopy. Immersion echelle gratings with much coarser grooves being developed by us at LLNL will play a critical role in achieving high spectral resolution with a compact and low cost IR cryogenically cooled spectrograph and simultaneous large wavelength coverage on relatively small IR detectors. We have constructed a new A0 optimized spectrograph at Steward Observatory to provide R = 200,000 in the optical, which is being commissioned at the Starfire Optical Range 3.5m telescope. We have completed the optical design of the LLNL IR Immersion Spectrograph (LISPEC) to take advantage of improved silicon etching technology. Key words: adaptive optics, spectroscopy, high resolution, immersion gratings

We describe results from the first multi-laser wavefront sensing system designed to support tomographic modes of adaptive optics (AO). The system, now operating at the 6.5 m MMT telescope in Arizona, creates five beacons by Rayleigh scattering of laser beams at 532 nm integrated over a range from 20 to 29 km by dynamic refocus of the telescope optics. The return light is analyzed by a Shack-Hartmann sensor that places all five beacons on a single detector, with electronic shuttering to implement the beacon range gate. A separate high-order Shack-Hartmann sensor records simultaneous measurements of wavefronts from a natural star. From open-loop measurements, we find the average beacon wavefront gives a good estimate of ground layer aberration. We present results of full tomographic wavefront analysis, enabled by supplementing the laser data with simultaneous fast image motion measurements from three stars in the field. We describe plans for an early demonstration at the MMT of closed-loop ground layer AO, and later tomographic AO.

We describe a new wavefront sensor based on the efficient Shack-Hartmann quad cell system. The key improvement to existing designs is a modified lenslet array. The traditional refractive lenslet array is replaced with a segmented reflective system that allows individual control of each subaperture. This system has produced diffraction limited slope correction of the six 1.83 m mirrors of the MMT using a 9.9 V magnitudeguide star and significant image improvement on guide stars as faint as 11.3 V magnitude, limited by the readout noise of the CCD quad cell detector. Recent experiements with an improved detector diffraction limited imaging on guide stars as faint as 15th magnitude. This optimized wavefront sensor, equally applicable to filled aperture telescopes, promises to extend the amount of sky coverage available for adaptive correction in the near IR.

We report results from an adaptive optics system designed to provide imaging at the diffraction limit of resolution in the near-infrared at the Multiple Mirror Telescope (MMT). For the present experiment, the aperture consisted of five of the six primary mirrors of the MMT, operating as a coherently phased array. The largest components of the atmospherically induced wave-front aberration are the fluctuations in mean phase between the segments. These errors were derived in real time from the Fourier transform of short-exposure stellar images at 2.2 microns and corrected at an image of the telescope pupil with piston motion from a segmented adaptive mirror. At a correction rate of 43 Hz, this level of adaptive control resulted in an integrated image with a clear diffraction-limited component of 0.075 arcsec FWHM. This stabilized component is present directly in the light arriving at the detector and is not the result of postprocessing. We discuss future improvements to our adaptive wave-front control and its application to astronomical observations.

The first results from an adaptive optics system operating on-line at the telescope with the wavefront aberration sensed by a trained artificial neural network are presented. Star images were formed at 2.2 μm wavelength by two coherently phased apertures of the Multiple Mirror Telescope (MMT), and analyzed by the neural net. The net derives wavefront parameters in a few milliseconds, and the system performance is fast enough that the aberration is nearly frozen during the time needed to make a correction. With the servo loop in operation, the corrected image shows significant power at the diffraction limit of 0.1″