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Saturn's wayward shepherds: the peregrinations of Prometheus and Pandora
French, Richard G.; Dones, Luke; Lissauer, Jack J. +1 more
Saturn's narrow F ring is flanked by two nearby small satellites, Prometheus and Pandora, discovered in Voyager images taken in 1980 and 1981 (Synnott et al., 1983, Icarus 53, 156-158). Observations with the Hubble Space Telescope (HST) during the ring plane crossings (RPX) of 1995 led to the unexpected finding that Prometheus was ∼19° behind its …
Photometry of pluto in the last decade and before: evidence for volatile transport?
Buratti, B. J.; Heinze, A.; Young, J. +7 more
Photometric observations of Pluto in the BVR filter system were obtained in 1999 and in 1990-1993, and observations in the 0.89-µm methane absorption band were obtained in 2000. Our 1999 observations yield lightcurve amplitudes of 0.30 ± 0.01, 0.26 ± 0.01, and 0.21 ± 0.02 and geometric albedos of 0.44 ± 0.04, 0.52 ± 0.03, and 0.58 ± 0.02 in …
The dynamics of jovian white ovals from formation to merger
Marcus, Philip S.; Youssef, Ashraf
In early 1998 two of the three, long-lived anticyclonic, jovian white ovals merged. In 2000 the two remaining white ovals merged into one. Here we examine that behavior, as well as the dynamics of three earlier epochs: the Formation Epoch (1939-1941), during which a nearly axisymmetric band broke apart to form the vortices; the Kármán Vortex Stree…
The mass ratio of Charon to Pluto from Hubble Space Telescope astrometry with the fine guidance sensors
Olkin, C. B.; Franz, O. G.; Wasserman, L. H.
The mass ratio of Charon to Pluto is a basic parameter describing the binary system and is necessary for determining the individual masses and densities of these two bodies. Previous measurements of the mass ratio have been made, but the solutions differ significantly (Null et al., 1993; Young et al., 1994; Null and Owen, 1996; Foust et al., 1997;…
EPIC simulations of the merger of Jupiter's White Ovals BE and FA: altitude-dependent behavior
Dowling, Timothy E.; Sánchez-Lavega, Agustín.; Morales-Juberías, Raúl
Observations of the merger of Jupiter's White Ovals BE and FA show altitude-dependent behavior that we seek to capture in numerical simulations. In particular, it was observed that the upper portions of the vortices orbited each other before merging, but the lower portions translated into each other without orbiting, a phenomenon we term the pair-…
The nature of Neptune's increasing brightness: evidence for a seasonal response *
Baines, K. H.; Sromovsky, L. A.; Fry, P. M. +1 more
Hubble Space Telescope (HST) observations in August 2002 show that Neptune's disk-averaged reflectivity increased significantly since 1996, by 3.2 ± 0.3% at 467 nm, 5.6 ± 0.6% at 673 nm, and 40 ± 4% in the 850-1000 nm band, which mainly results from dramatic brightness increases in restricted latitude bands. When 467-nm HST observations from 1994 …
Vesta's UV lightcurve: hemispheric variation in brightness and spectral reversal
Vilas, Faith; Hendrix, Amanda R.; Festou, Michel C.
Spectra of asteroid 4 Vesta obtained in October 1990 with the International Ultraviolet Explorer are reanalyzed and reinterpreted. A large portion of the eastern hemisphere (based on the prime meridian definition of Thomas et al., 1997a) is darker at UV wavelengths than much of the western hemisphere. The UV lightcurve is in contrast with the visi…
Mars atmospheric water vapor abundance: 1996-1997
Doose, L. R.; Hunten, D. M.; Sprague, A. L. +1 more
Measurements of martian atmospheric water vapor made throughout Ls = 18.0°-146.4° (October 3, 1996-July 12, 1997) show changes in Mars humidity on hourly, daily, and seasonal time scales. Because our observing program during the 1996-1997 Mars apparition did not include concomitant measurement of nearby CO 2 bands, high north…
Voyager color photometry of Saturn's main rings: a correction
Showalter, Mark R.; Cuzzi, Jeffrey N.; Estrada, Paul R.
We correct a calibration error in our earlier analysis of Voyager color observations of Saturn's main rings at 14° phase angle (Estrada and Cuzzi, 1996, Icarus 122, 251) and present thoroughly revised and reanalyzed radial profiles of the brightness of the main rings in the Voyager green, violet, and ultraviolet filters and the ratios of these bri…
H 2O- and OH-bearing minerals in the martian regolith: . analysis of 1997 observations from HST/NICMOS
Gordon, K. D.; Wolff, M. J.; Noe Dobrea, E. Z. +1 more
We have analyzed observations of the Acidalia hemisphere of Mars taken by the Hubble Space Telescope's Near-Infrared Camera Multi-Object Spectrograph (HST/NICMOS) during July of 1997 ( Ls=152°, northern martian summer). The data consist of images at ∼60 km/pixel resolution, using both narrow- and medium-band filters specifically selecte…