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Geologic Mapping of Vesta from 1994 Hubble Space Telescope Images
Wells, Eddie N.; Storrs, Alex D.; Thomas, Peter C. +3 more
We utilize the 56 images of Asteroid 4 Vesta obtained through four mineralogically diagnostic filters by the Hubble Space Telescope (Zellneret al.1997,Icarus) to construct a geologic map. Vesta's surface is found to be geologically diverse and to be dichotomous at a hemispheric scale. The eastern hemisphere (longitude definition from Thomaset al.1…
Vesta: Spin Pole, Size, and Shape from HST Images
Storrs, Alex D.; Thomas, Peter C.; Binzel, Richard P. +3 more
HST images obtained over an interval of 71 hr at a scale of 52 km/pixel have been used to determine the spin pole, size, and shape of Vesta. Several bright and dark surface features allow control point stereogrammetric measurement of spin pole orientation. An independent solution of spin pole and shape can be made from the limb and terminator coor…
Separate Lightcurves of Pluto and Charon
Buie, Marc W.; Wasserman, Lawrence H.; Tholen, David J.
We present new Hubble Space Telescope observations of the Pluto-Charon system taken with WFPC1 (PC6) between 1992 May 21 and 1993 August 18. Our observations consist of 52 images with the F555W filter and 8 images in the F439W filter. From these data we extracted individual lightcurves, phase coefficients, and colors for Pluto and Charon. These li…
Volcanic Resurfacing of Io: Post-Repair HST Imaging
Gilmore, Diane; McGrath, Melissa A.; Spencer, John R. +4 more
In March 1994, we used the newly refurbished Hubble Space Telescope (HST) to obtain global imaging of Io at five wavelengths between 0.34 and 1.02 µm, with a spatial resolution of 160 km. The images provided the clearest view of Io since Voyager and the first systematic observations in the wavelength range 0.7-1.0 µm. We have produced …
Titan's North-South Asymmetry from HST and Voyager Imaging: Comparison with Models and Ground-Based Photometry
Karkoschka, Erich; Lorenz, Ralph D.; Lemmon, Mark T. +3 more
New measurements of Titan's hemispheric brightness asymmetry from HST images from 260 to 1040 nm show that the contrast is strongest near 450 nm (blue) and, with the opposite sign, at 889 nm (methane band). Comparison with a full Titan year of disk-integrated albedo data indicates that the seasonal cycle in asymmetry is smooth, but is insufficient…
Atmospheric Structure of Neptune in 1994, 1995, and 1996: HST Imaging at Multiple Wavelengths
Hammel, H. B.; Lockwood, G. W.
Hubble Space Telescope imaging of Neptune in 1994, 1995, and 1996 reveals changes in atmospheric features. Dark spots at 467 nm near latitude +31° were present in both 1994 and 1995, but absent from images in March 1996. However, a larger data set in August 1996 (Sromovskyet al., Bull. Am. Astron. Soc.28,1077, 1996) revealed a dark spot. The featu…
The Orbit of Charon
Buie, Marc W.; Tholen, David J.
The orbit of Charon has been determined from 60 images of the Pluto-Charon system acquired with the Hubble Space Telescope Wide Field and Planetary Camera between 1992 May 21 and 1993 August 18. The semimajor axis was found to be 19,636 ± 8 km, in good agreement with an older determination upon which mutual-event-based radius computations have rel…
Hubble Space Telescope Images of Asteroid 4 Vesta in 1994
Wells, Eddie N.; Storrs, Alex D.; Thomas, Peter C. +4 more
The Planetary Camera of the WFPC2 on board the Hubble Space Telescope was used in late 1994 to record 56 images of Asteroid 4 Vesta in four compositionally diagnostic wavelength bands. The images were taken at eight epochs to give global coverage of Vesta at an aspect of approximately 16° north latitude. The prograde rotation of Vesta is clearly r…
Rings and Satellites of Uranus: Colorful and Not So Dark
Karkoschka, Erich
Photometric properties of nine uranian satellites and four rings, based on six Hubble Space Telescope images taken in 1995, are presented. Derived albedos are consistent with previous data taken at the same phase angle of 1°, but inconsistent with most Voyager-based estimates extrapolated from observations at phase angles above 15°. The shape of p…
Atomic Sulfur in Cometary Comae Based on UV Spectra of the S ITriplet near 1814 Å
A'Hearn, Michael F.; Meier, Roland
We present a detailed study of the S I triplet emissions near 1814 Å in a variety of comets. Even in a moderately dense cometary coma the ground-state component (1807 Å) of the triplet turns out to be more or less optically deep. Therefore, any straightforward interpretation of the measured S I flux in terms of a gfactor and a column density is in…