Publications (3)0 Total impact
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Article: FIRST ASTRONOMICAL IMAGES SHARPENED WITH ADAPTIVE OPTICS USING A SODIUM LASER GUIDE STAR M. Lloyd-Hart, J. R. P. Angel, T. D. Groesbeck, T. Martinez, B. P. Jacobsen, B. A. McLeod
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ABSTRACT: 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 K s -band with image resolution of 0.51, when the uncorrected resolution was 0.72. 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 K s = 17.5 can be identified in the corrected image. The 0.5 imaging capability here demonstrated, 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 0.5 resolution is much larger than the d...06/2000; -
Article: P.M. Gray, M. LloydHart, J.R.P. Angel, D.W. McCarthy, Jr., D.G. Sandler
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ABSTRACT: A new adaptive optics system has been constructed for moderately high resolution in the near infrared at the Multiple Mirror Telescope #MMT#. The system, called FASTTRAC II, has been designed to combine the highest throughput with the lowest possible background emission by making the adaptive optical element be an existing and necessary part of the telescope, and by eliminating all warm surfaces between the telescope and the science camera's dewar. At present, only natural guide stars are supported, but by the end of 1995, we will add the capability to use a single sodium resonance beacon derived from a laser beam projected nearly coaxially with the telescope. In this paper, we present a description of FASTTRAC II, and show results from its #rst test run at the telescope in April 1995. Keywords: adaptive optics, atmospheric turbulence, telescopes, optical design, control systems, actuators 1. INTRODUCTION In 1996, the existing Multiple Mirror Telescope #MMT# is scheduled to be replac...06/2000; -
Article: High Resolution Imaging with Adaptive Optics at the Multiple Mirror Telescope
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ABSTRACT: We present the latest results from an adaptive optics program being implemented at the MMT using a six element adaptive mirror. The tilt of the wavefront over each of the six telescopes is determined with a Shack-Hartmann type sensor using a 24times 24 pixel low-noise CCD. This system allows the MMT to operate at a resolution of 0.3'' at 2 microns -- near the diffraction limit of the individual 1.8-m telescopes. This resolution can be obtained within ~ 1' of any star with visual magnitude < 16, allowing high-resolution near-IR imaging with a NICMOS2 array of a wide variety of targets, including high-redshift galaxies and young and evolved stars. This system can also be used with the MMT operated as a phased array telescope. In this mode, the piston errors between the telescopes are determined by examining the Fourier transform of the combined 2-micron image of the natural guide star using a fast-readout InSb array. In this configuration we have achieved a resolution of 0.075''. In good seeing we expect to obtain images of interest within the isoplanatic patch of guide stars with K magnitude <7. We acknowledge financial support from the NSF (AST92-03336) and the Flintridge Foundation. The adaptive mirror was donated by ThermoTrex Corp.11/1992; 24:1240.
