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We present results from 14 nights of observations of Titan in 1996-1998 using near-infrared (centered at 2.1 microns) speckle imaging at the 10-meter W.M. Keck Telescope. The observations have a spatial resolution of 0.06 arcseconds. We detect bright clouds on three days in October 1998, with a brightness about 0.5% of the brightness of Titan. Using a 16-stream radiative transfer model (DISORT) to...
For part I see ibid., p.3326-32 (2004). Fundamental theory is derived for control of adaptive optics used in astronomical telescopes, and for possible other applications involving shape control, vibrations, and other spatial control problems in which the control system acts much faster than a fixed process, or the observable and controllable subspaces are both finite dimensional. The theory is developed...
The theory of a spatial non-dynamic LQG controller developed in Part II is applied to astronomical adaptive optics (AO). The AO control system is described and reduced to an exact finite dimensional model by projecting into observable and controllable subspaces. A dynamic optimal minimum variance controller is derived, using the estimated covariance of the residuals rather than assuming a Komolgorov...
We report on observations of Neptune from the 10-meter W.M. Keck II Telescope on June 17-18 (UT) 2000 and August 2-3 (UT) 2002 using the adaptive optics (AO) system to obtain a spatial resolution of 0.06 arcseconds. With this spatial resolution we can obtain spectra of individual bright features on the disk of Neptune in a filter centered near 2 microns. The use of a gas-only, simple reflecting layer...
Using speckle imaging techniques on the 10-m W.M. Keck I telescope, we observed near-infrared emission at 2.2 μm from volcanic hotspots on Io in July-August 1998. Using several hundreds of short-exposure images we reconstructed diffraction-limited images of Io on each of three nights. We measured the positions of individual hotspots to +/-0.004'' or better, corresponding to a relative positional error...
Saturn's large moon Titan is unique among planetary satellites in that it possesses a thick atmosphere and a haze layer that is opaque to visible light. This haze is believed to be composed of organic compounds produced by the photolysis of methane. It has been suggested that the photochemical products of methane photolysis, primarily ethane, would “rain out” over time and may produce reservoirs of...
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