Search Publications
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…
Latitudinal Distribution of O 2on Ganymede: Observations with the Hubble Space Telescope
Spencer, John R.; Calvin, Wendy M.
To help constrain the spatial variation of oxygen on Jupiter's satellite Ganymede, and hence have more clues to its mode of production and stability, we have obtained spectral data from the Faint Object Spectrograph (FOS) for a single pole-to-pole latitudinal strip, along with several Wide Field Planetary Camera 2 (WFPC2) images in three narrow ba…
Latitudinal Variation of Aerosol Sizes Inferred from Titan's Shadow
Karkoschka, Erich; Lorenz, Ralph D.
We measured the location, size, and shape of Titan's shadow in five images taken with the Hubble Space Telescope in 1995. We inferred the altitude of Titan's optical limb at wavelengths of 337-954 nm to an accuracy of 15 km. At each wavelength, altitudes are constant north of -5° and also constant but lower south of -50° latitude, with a linear tr…
NOTE: an HST Search for Magnesium in the Lunar Atmosphere
Parker, Joel Wm.; Stern, S. Alan; Mendillo, Michael +5 more
In October 1996 we used the Hubble Space Telescope's Faint Object Spectrograph to make the first-ever mid-ultraviolet spectroscopic search for emissions from the lunar atmosphere. This spectrum revealed no emission lines, despite the fact that strong resonance emission transitions from the Al, Si, and Mg neutrals and from Mg+occur in th…
Temperatures and Altitudes of Jupiter's Ultraviolet Aurora Inferred from GHRS Observations with the Hubble Space Telescope
Fox, J. L.; Caldwell, John J.; Kim, Y. H.
We observed the jovian UV auroral regions with the Goddard high resolution spectrograph (GHRS) on board the Hubble Space Telescope (HST) on Apr. 29, May 2, and June 10, 1995. Observations of target areas were made in pairs in the two wavelength ranges 1257-1293 Å and 1587-1621 Å. Spectra in the long wavelength range are dominated by emissions of t…