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Ammonia and Eddy Mixing Variations in the Upper Troposphere of Jupiter from HST Faint Object Spectrograph Observations
Simon, A. A.; Edgington, S. G.; Atreya, S. K. +4 more
Ultraviolet spectra of the northern and southern hemispheres of Jupiter taken with the Hubble Space Telescope Faint Object Spectrograph (FOS) in May 1992 and June 1993 have been used to derive the altitude profiles of NH 3 in the vicinity of the tropopause. For a given pressure level, it is shown that the vertical profile of ammonia var…
Large Craters on Small Objects: Occurrence, Morphology, and Effects
Thomas, P. C.
Spacecraft imaging data allow an accounting of the occurrence and characteristics of the largest craters on small asteroids and satellites. Data covering Phobos, Deimos, Gaspra, Ida, Mathilde, Vesta, Amalthea, Thebe, Janus, Epimetheus, Hyperion, and Proteus show that ∼50% of rocky objects support craters with diameters of 1 object mean radius (R <…
Constraints on the Tropospheric Cloud Structure of Jupiter from Spectroscopy in the 5-µm Region: A Comparison between Voyager/IRIS, Galileo-NIMS, and ISO-SWS Spectra
Carlson, R. W.; Drossart, P.; Encrenaz, Th. +2 more
The 5-µm window in the spectrum of Jupiter is one of the few regions that gives access to the vertical structure of the troposphere between pressure levels of approximately 4 and 8 bar. Voyager/IRIS spectra obtained in 1979 during the Voyager flybys have been analyzed intensively over the past two decades. Most of these analyses concluded on…
Telescopic Observations of Mars, 1996-1997: Results of the Marswatch Program
Parker, D. C.; Beish, J. D.; Troiani, D. M. +2 more
During the 1996-1997 apparition of Mars, Marswatch and the International Mars Patrol (IMP) of the Mars Section of the Association of Lunar and Planetary Observers (ALPO) received 2750 observations from 70 observers in 14 countries. Approximately 40% of these observations are CCD images, many of which were obtained through filters covering a spectr…
HST Detection of H 2 Raman Scattering in the Jovian Atmosphere
Yelle, Roger V.; Bétremieux, Yan
Raman scattered features by molecular hydrogen have been detected in Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) observations of Jupiter. The measurements were obtained with the G190H grating and red detector combination spanning 158.0-232.0 nm at about 0.3 nm resolution. The data were corrected for scattered light, and careful mo…
Infrared Spectral Imaging of Martian Clouds and Ices
Bell, James F.; Howell, Robert R.; Klassen, David R. +4 more
Multispectral images of Mars, taken at the NASA Infrared Telescope Facility (IRTF) near and at the 1995 opposition, are used to identify and track its atmospheric clouds and ground ices. Band depth mapping is used to help distinguish between the composition of volatiles and provide a check for the techniques of principal components analysis (PCA) …
Martian North Polar Cap 1996-1997
Iwasaki, Kyosuke; Parker, Donald C.; Larson, Steve +1 more
In order to investigate the interannual variability of the regression of the martian north polar cap, the regression of the martian north polar cap during the 1996-1997 apparition is examined utilizing measurements with CCD images.
The regression of the north polar cap in 1996-1997 as determined from our measurements is in excellent agreement…Phobos Disk-Integrated Photometry: 1994-1997 HST Observations
Thomas, Peter C.; Wolff, Michael J.; Cantor, Bruce A. +2 more
A program of synoptic monitoring of Mars was carried out with the Hubble Space Telescope from August 8, 1994, through October 9, 1997, using the Wide Field Planetary Camera 2 (WFPC2). With the improved optics of the WFPC2 and the high angular resolution of the Planetary Camera (0.0442-0.0455 arcsec/pixel) we have been able to use these images to s…
Near Infrared Photometry of the Jovian Ring and Adrastea
Terrile, Richard J.; Smith, Bradford A.; Owen, Tobias C. +2 more
The near IR spectral reflectance of the Jupiter dust ring is poorly known because of problems with scattered light from the planet. Here we report colors for the jovian ring and one of the two ring satellites, Adrastea, using observations from the near-IR camera NICMOS on the Hubble Space Telescope. Near the time when the Earth crossed the jovian …
ISOPHOT Polarization Measurements of the Asteroids (6) Hebe and (9) Metis at 25 µm
Erikson, A.; Müller, T. G.; Klaas, U. +1 more
The subsurface thermal IR emission of asteroids becomes linearly polarized when scattered across the surface. The disk integrated mid-IR Stokes parameters are computed by extending the new thermophysical model by Lagerros (1996, Astron. Astrophys.315, 625-632; 1998, Astron. Astrophys.332, 1123-1132). The small scale surface roughness is approximat…