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New Measurements of the Winds of Uranus
Karkoschka, E.; Hammel, H. B.; de Pater, I. +2 more
Hubble Space Telescope imaging of Uranus in 1994, 1997, 1998, and 2000 revealed 13 cloud features, allowing the first measurements of wind velocities at northern latitudes not accessible to the Voyager cameras and new measurements of southern-latitude wind velocities determined during the 1986 Voyager encounter. Images acquired with the Keck 10-me…
Neptune's Atmospheric Circulation and Cloud Morphology: Changes Revealed by 1998 HST Imaging
Baines, K. H.; Sromovsky, L. A.; Fry, P. M. +2 more
On 11-12 August 1998, we imaged Neptune using the Hubble Space Telescope WFPC2 CCD camera and NICMOS InSb camera to obtain high-spatial-resolution, absolutely calibrated imagery from the visible through the near infrared. We used nine HST orbits to intensively sample one rotation of Neptune, and four additional orbits to sample cloud evolution and…
EPIC Simulations of Bright Companions to Neptune's Great Dark Spots
Sromovsky, L. A.; Showman, A. P.; Dowling, T. E. +1 more
We present a three-dimensional model of the bright companion clouds associated with Neptune's Great Dark Spots (GDSs). Our results support the hypothesis that the bright companions of the southern-hemisphere GDS discovered in 1989 and of the northern-hemisphere GDS discovered in 1994 are methane clouds that form at or just below the tropopause and…
HST Observations of Saturnian Satellites during the 1995 Ring Plane Crossings
Nicholson, Philip D.; French, Richard G.; McGhee, Colleen A. +1 more
In May, August, and November 1995, Hubble Space Telescope (HST) observations during Saturn's ring-plane crossings allowed us to view saturnian satellites normally hidden to Earth-based observers in the glare of the rings. New measurements of Janus, Epimetheus, Prometheus, and Pandora have been combined to form revised orbital solutions using all t…
Hubble Space Telescope Observations of the Nucleus of Comet 9P/Tempel 1
Lamy, P. L.; A'Hearn, M. F.; Toth, I. +2 more
The nucleus of Comet 9P/Tempel 1, the target of the Deep Impact mission, was detected during Hubble Space Telescope observations taken with the wide-field planetary camera 2 (WFPC2) on 31 December 1997 when the comet's solar phase angle was 3.°8, its heliocentric distance was 4.48 AU, and its geocentric distance was 3.53 AU. Sixteen images were ta…
Coordinated 1996 HST and IRTF Imaging of Neptune and Triton. II. Implications of Disk-Integrated Photometry
Baines, K. H.; Sromovsky, L. A.; Fry, P. M. +1 more
Near-IR groundbased observations coordinated with Wide Field Planetary Camera 2 (WFPC2) HST observations (Sromovsky et al.Icarus149, 416-434, 459-488) provide new insights into the variations of Neptune and Triton over a variety of time scales. From 1996 WFPC2 imaging we find that a broad circumpolar nonaxisymmetric dark band dominates Neptune's l…
Water Production of Comets 2P/Encke and 81P/Wild 2 Derived from SWAN Observations during the 1997 Apparition
Schmidt, W.; Bertaux, J. -L.; Lallement, R. +5 more
The water production rates of comets 2P/Encke and 81P/Wild 2 during their 1997 apparitions have been estimated from Lyman-α observations of the SWAN instrument and compared to previously published values. 2P/Encke was detected 28 times from few days preperihelion to 1.4 AU postperihelion with a perihelion water production rate QH 2…
Uranus' Apparent Seasonal Variability in 25 HST Filters
Karkoschka, Erich
Hubble Space Telescope (HST) images of Uranus taken in 1997 reveal that Voyager's view of the southern hemisphere was not representative of the rest of the planet. The banded structure with hemispherical asymmetry, presented in 25 filters between 0.27 and 2.03 µm wavelength, caused Uranus' full disk to darken by as much as 35% between 1985 a…
NOTE: HST/FGS Observations of the Asteroid (216) Kleopatra
Lattanzi, M. G.; Tanga, P.; Berthier, J. +4 more
Interferometric observations of asteroid (216) Kleopatra were performed in January 2000 using the Fine Guidance Sensors (FGS) aboard HST. The FGS data obtained clearly suggest that (216) Kleopatra is composed of two lobes in contact, in agreement with the radar data (Ostro et al. 2000, Science288, 836-839), and provide more precise constraints on …
An HST Study of Jovian Chromophores
Simon-Miller, Amy A.; Gierasch, Peter J.; Banfield, Don
A principal components analysis was performed on Hubble Space Telescope WFPC2 images of Jupiter from October 1995 and October 1996. Global maps in the F410M, F555W, F673N, and F953N filters were analyzed. These are continuum wavelengths in Jupiter's spectrum, sensitive to reflection from the visible cloud deck. The primary principal components cor…