Titan: High-Resolution Speckle Images from the Keck Telescope

Gibbard, S. G.; Macintosh, Bruce; Gavel, Donald T.; Max, C. E.; Pater, Imke de; Ghez, A. M.; Young, E. F.; McKay, Christopher P.

doi:10.1006/icar.1999.6095

Cited by 72 publications

(74 citation statements)

References 44 publications

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“…The '' recommended '' atmospheric profile of Yelle et al (1997) is used, and on the basis of the analysis of Gibbard et al (1999), the total opacity of haze is set to 0.2. The fractional abundance of H 2 is set to 0.0011 (Samuelson et al 1997) throughout the atmosphere.…”

Section: Appendix a Radiative Transfer Calculationsmentioning

confidence: 99%

Titan’s Clouds from Gemini and Keck Adaptive Optics Imaging

Roe¹,

Pater²,

Macintosh³

2002

ApJ

Self Cite

115

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Using adaptive optics on the Gemini and Keck II telescopes, we found a thin haze and discrete clouds in Titan's south polar troposphere. The discrete clouds vary on timescales of a few hours. We propose a seasonal mechanism to explain the formation of this spring polar tropospheric haze. Assuming that the clouds are located in or above the haze, we suggest that convection within this haze layer triggers methane condensation; subsequent latent heat release leads to vigorous convection and formation of transient clouds. Our results have significant implications for planning the Cassini mission flybys of Titan.

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Section: Appendix a Radiative Transfer Calculationsmentioning

confidence: 99%

Titan’s Clouds from Gemini and Keck Adaptive Optics Imaging

Roe¹,

Pater²,

Macintosh³

2002

ApJ

Self Cite

115

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“…Recently, ground-based observations have shown that Titan has a light curve due to surface albedo features that are visible in methane continuum regions from 0.93 to 2.03 µm (Lemmon et al 1993(Lemmon et al , 1995Griffith 1993;Coustenis et al 1995). Observations with the Hubble Space Telescope have been used to map the surface features responsible for the light curve in many of the methane windows (Smith et al 1996, Meier et al 2000, and ground-based adaptive optics (Combes et al 1997) and speckle (Gibbard et al 1999) images have shown surface features at the longer wavelengths. Visibility of the surface indicates a two-way transmission of the light, which we can use to measure the methane abundance.…”

Section: Introductionmentioning

confidence: 99%

Methane Abundance on Titan, Measured by the Space Telescope Imaging Spectrograph

Lemmon

Smith

Lorenz

2002

Icarus

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Although methane is the dominant absorber in Titan's reflection spectrum, the amount of methane in the atmosphere has only been determined to an order of magnitude. We analyzed spectra from the Space Telescope Imaging Spectrograph, looking at both a bright surface region (700-km radius) and a dark surface region. The difference between the spectra of the two regions is attributed to light that has scattered off the surface, and therefore made a roundtrip through all of Titan's methane. Considering only absorption, the shape of the difference spectrum provides an upper limit on methane abundance of 3.5 km-am. Modeling the multiple scattering in the atmosphere further constrains the methane abundance to 2.63 ± 0.17 km-am. In the absence of supersaturation and with a simplified methane vertical profile, this corresponds to a surface methane-mole fraction near 3.8% and a relative humidity of 0.32. With supersaturation near the tropopause, the surface methane mole fraction could be as low as 3%. c 2002 Elsevier Science (USA)

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“…Although images from space telescopes and exploratory spacecrafts are available today, high-resolution imaging of planets and the satellites in the solar system using a ground-based telescope is still necessary for continuous longterm observations of their surfaces. The results of the speckle imaging for Neptune, Titan, Io and other objects have been reported by several authors (Beletic & Goody 1992;Gibbard et al 1998;Macintosh et al 2003), who have used Knox-Thompson and/or the triple correlation methods. However, to our knowledge, speckle imaging with SAA has not been ever tried for such objects.…”

Section: Introductionmentioning

confidence: 63%

Image Restoration of Io by Shift-and-Add Method and Deconvolution

Kuwamura

Tsumuraya²,

Miura

et al. 2008

PUBL ASTRON SOC PAC

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ABSTRACT. Atmospheric turbulence degrades the image resolution of a ground-based telescope, and a speckle imaging technique can restore the image with high resolution up to the diffraction limit. We have obtained the speckle data of Io (a Jupiter's satellite) using the 2 m telescope in Nishi-Harima Astronomical Observatory. The speckle data are reduced by the shift-and-add method followed by a background-subtraction procedure. The reduced image is then deconvolved by the similarly reduced image of the unresolved binary star HR6168. The comparison with the close-up image taken by the Voyager 2 spacecraft reveals that the restored image shows well-resolved structural features on the surface of Io.

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Titan: High-Resolution Speckle Images from the Keck Telescope

Cited by 72 publications

References 44 publications

Titan’s Clouds from Gemini and Keck Adaptive Optics Imaging

Titan’s Clouds from Gemini and Keck Adaptive Optics Imaging

Methane Abundance on Titan, Measured by the Space Telescope Imaging Spectrograph

Image Restoration of Io by Shift-and-Add Method and Deconvolution

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