Multi‐spectral simultaneous observations of Saturn's aurorae in Jan. 2009

Conference (2012)

HST STIS Observations of Saturn's Auroral Variations Concurrent with the Cassini Solar Wind Campaign in Jan. 2004

Conference (2004, May 17)

Saturn's magnetosphere is often referred to as "intermediate between the cases of the Earth and Jupiter". Due to very limited measurements of Saturn's magnetosphere and auroral activity, however, it has ... [more ▼]

Saturn's magnetosphere is often referred to as "intermediate between the cases of the Earth and Jupiter". Due to very limited measurements of Saturn's magnetosphere and auroral activity, however, it has never been clear in detail what this statement means. A recent campaign of HST STIS UV imaging of Saturn's aurora has been carried out over 8-30 Jan. 2004 concurrent with measurements of the approaching solar wind by Cassini. This imaging set is much more comprehensive than any earlier observations of Saturn's aurora, obtained at a time when Saturn's southern auroral oval is completely visible due to the large apparent tilt of Saturn. The data provide the opportunity to determine the mean distribution of the auroral emissions, the degree of corotation of any bright regions, any variations with local time of the emissions, the latitudinal motions of the main oval with time and location, and other parameters. In addition, each of these can be compared with the approaching solar wind conditions and Saturn's kilometric radiation (SKR) intensity from Cassini measurements. Quick looks at the data from HST and Cassini demonstrate that the measurements have been made successfully, and the coverage includes dramatic variations in Saturn's auroral activity as well as at least two solar wind shocks passing Cassini. This presentation will concentrate on the measured properties of Saturn's aurora in the context of comparisons with the magnetospheres of the Earth and Jupiter. [less ▲]

Ultraviolet observations of the Saturnian north aurora and polar haze distribution with the HST-FOC

in NASA STI/Recon Technical Report N (1995), 96

Near simultaneous observations of the Saturnian H2 north ultraviolet aurora and the polar haze were made at 153 nm and 210 nm respectively with the Faint Object Camera on board the Hubble Space Telescope ... [more ▼]

Near simultaneous observations of the Saturnian H2 north ultraviolet aurora and the polar haze were made at 153 nm and 210 nm respectively with the Faint Object Camera on board the Hubble Space Telescope. The auroral observations cover a complete rotation of the planet and, when co-added, reveal the presence of an auroral emission near 80 deg N with a peak brightness of about 150 kR of total H2 emission. The maximum optical depth of the polar haze layer is found to be located approximately 5 deg equatorward of the auroral emission zone. The haze particles are presumably formed by hydrocarbon aerosols initiated by H2+ auroral production. In this case, the observed haze optical depth requires an efficiency of aerosol formation of about 6 percent, indicating that auroral production of hydrocarbon aerosols is a viable source of high-latitude haze. [less ▲]

HST-FOC observations of a remarkable UV auroral event on Jupiter

in NASA STI/Recon Technical Report N (1994), 95

Two sets of UV (ultraviolet) images of the Jovian north aurora were obtained with the Faint Object Camera (FOC) on Hubble. The first series shows a very intense discrete arc in corotation with the planet ... [more ▼]

Two sets of UV (ultraviolet) images of the Jovian north aurora were obtained with the Faint Object Camera (FOC) on Hubble. The first series shows a very intense discrete arc in corotation with the planet. The maximum apparent H2 emission rate corresponds to an electron precipitation of approximately 1/sq Wm, a very large flux in comparison with the solar EUV (extreme ultraviolet) heating. The hugh particle heating rate of the auroral upper atmosphere of Jupiter is expected to cause a large transient temperature increase and generate strong thermospheric winds. Twenty hours later, the discrete arc had considerably decreased in brightness. The timescale and magnitude of the change in the UV aurora strongly suggests that the discrete Jovian auroral precipitation is related to large scale current system variations as are the Earth's discrete aurorae. [less ▲]

Ultraviolet imaging of the Jovian aurora with the Hubble Space Telescope

in Geophysical Research Letters (1992), 19

We present here for the first time a Lyman-alpha image of the north polar region of Jupiter obtained with the Faint Object Camera on board the Hubble Space Telescope a few hours after the encounter of the ... [more ▼]

We present here for the first time a Lyman-alpha image of the north polar region of Jupiter obtained with the Faint Object Camera on board the Hubble Space Telescope a few hours after the encounter of the ULYSSES spacecraft with Jupiter. The presence of high latitude regions of enhanced emission is clearly observed. A comparison with the location of the 'UVS oval', the Io (L = 6) and high-latitude field-line footprints shows that the best agreement is obtained with the L not less than 15 footprint and the UVS oval which are close to each other for the particular longitudinal sector observed. These two L-shells correspond to two possible sources of precipitation: particles originating respectively from the region of the plasma torus of Io in a distorted magnetic field or particles from the distant magnetosphere by analogy with the terrestrial aurora. [less ▲]

Study of the neutral and ionized Io tori

in The Messenger (1987)

Images of Io were obtained with the 2.2-m telescope at La Silla in the imaging code coupled with a CCD detector. The strong emission from Io's continuum was significantly decreased through the use of an ... [more ▼]

Images of Io were obtained with the 2.2-m telescope at La Silla in the imaging code coupled with a CCD detector. The strong emission from Io's continuum was significantly decreased through the use of an occulting mask in the telescope focal plane. It was found that a spectral resolution of 5 A or better was desirable. [less ▲]