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Detection of SO₂ on Callisto with the Hubble Space Telescope

Johnson, Robert E.; McGrath, Melissa A.; Noll, Keith S. +1 more

We have detected SO₂ in ultraviolet spectra of Callisto obtained with the Hubble Space Telescope's Faint Object Spectrograph. An absorption band centered at 280 nm appears in the spectrum of Callisto's leading hemisphere, but is not apparent in the spectrum of the trailing hemisphere. The band is similar to the SO₂ band on Eu…

The Pele Plume (Io): Observations with the Hubble Space Telescope

Ballester, Gilda E.; McGrath, Melissa A.; Spencer, John R. +3 more

In July 1996, with the Hubble Space Telescope (HST), we observed the Pele plume silhouetted against Jupiter at a wavelength of 0.27µm, the first definitive observation of an Io plume from Earth. The height, 420 ± 40 km, was greater than any plume observed by Voyager. The plume had significantly smaller optical depth at 0.34 and 0.41µm, where it wa…