References of "Gladstone, R"
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See detailThe Degree of Correlation of Jovian and Saturnian Auroral Emissions With Solar Wind Conditions
Clarke, J. T.; Nichols, J.; Gérard, Jean-Claude ULg et al

Conference (2008, December 01)

While the terrestrial aurorae are known to be driven primarily by the interaction of the Earth's magnetosphere with the solar wind, auroral emissions on Jupiter and Saturn are thought to be driven ... [more ▼]

While the terrestrial aurorae are known to be driven primarily by the interaction of the Earth's magnetosphere with the solar wind, auroral emissions on Jupiter and Saturn are thought to be driven primarily by internal processes, with the main energy source being the planets' rapid rotation. Limited evidence has suggested there might be some influence of the solar wind on Jupiter's aurorae, and indicated that auroral storms on Saturn can occur at times of solar wind pressure increases. To investigate in detail the dependence of auroral processes on solar wind conditions, a large campaign of observations of these planets has been undertaken using the Hubble Space Telescope, in association with measurements from planetary spacecraft and solar wind conditions both propagated from one AU and measured near each planet. The data indicate a consistent brightening of both the auroral emissions and Saturn Kilometric Radiation (SKR) at Saturn close in time to the arrival of solar wind shocks and pressure increases, consistent with a direct physical relationship between Saturnian auroral processes and solar wind conditions. This correlation has been strengthened by the final campaign observations in Feb. 2008. At Jupiter the situation is less clear, with increases in total auroral power seen near the arrival of solar wind forward shocks, while little increase has been observed near reverse shocks. In addition, auroral dawn storms have been observed when there was little change in solar wind conditions. The data are consistent with some solar wind influence on some Jovian auroral processes, while the auroral activity also varies independently of the solar wind. This extensive data set will serve to constrain theoretical models for the interaction of the solar wind with the magnetospheres of Jupiter and Saturn. [less ▲]

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See detailThe HST UV Auroral Imaging Campaign of Jupiter and Saturn during the International Heliophysical Year
Clarke, J. T.; Gérard, Jean-Claude ULg; Grodent, Denis ULg et al

Conference (2006, December 01)

An extended campaign of observations of the UV auroral emissions from Jupiter and Saturn is scheduled for three periods beginning in Jan. 2007 and ending in late June 2008. This will be by far the most ... [more ▼]

An extended campaign of observations of the UV auroral emissions from Jupiter and Saturn is scheduled for three periods beginning in Jan. 2007 and ending in late June 2008. This will be by far the most extensive series of remote high resolution imaging of planetary aurora to date, and should provide new physical insight into the cause and effect relationships governing the controlling processes for the giant planet auroral emissions. These observations will overlap with in situ measurements of local solar wind and magnetospheric plasma conditions by Cassini at Saturn in Jan. 2007 and by the New Horizons mission approaching Jupiter in Feb. 2007. The UV auroral emission brightness and distributions will also be compared with extrapolated estimates of the solar wind conditions near each planet from periods just before planetary opposition in Jan. 2007 (Saturn) and June 2007 (Jupiter). The HST observations will also be coordinated with ground-based observations of near-IR auroral and nonthermal radio emissions. This paper will give an overview of the program, including the schedule of HST observations and the schedule of known coordinated observations. While a preliminary schedule has been submitted for the HST observations, this schedule will be finalized only when the HST orbit is sufficiently well known for the periods of observation for detailed pointing to be specified. By the time of Fall AGU, it should be possible to show the detailed schedule and pointing for the Jan-Feb 2007 observations. The paper will include a presentation of the plans for the rapid reduction and distribution of the HST auroral images to the community. [less ▲]

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See detailThe Solar Wind Upstream of Saturn: Cassini Plasma measurements and Saturn's Aurora
Crary, F. J.; Young, D. T.; Barraclough, B. et al

Conference (2004, May 17)

For a full solar rotation in January and early February, 2004, the Cassini spacecraft and Hubble and Chandra Space Telescopes were used to make simultaneous observations of the solar wind and Saturn's ... [more ▼]

For a full solar rotation in January and early February, 2004, the Cassini spacecraft and Hubble and Chandra Space Telescopes were used to make simultaneous observations of the solar wind and Saturn's aurora. We report here on initial results from data taken with the Cassini Plasma Spectrometer's electron and high-resolution ion sensors in the solar wind upstream of Saturn. These measurements, combined with those of other particles and fields instruments on Cassini show two shock and corotating interaction regions, which reached Saturn approximately twelve hours later. An auroral response to each of these events was observed by the Hubble Space Telescope. [less ▲]

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See detailHST STIS Observations of Saturn's Auroral Variations Concurrent with the Cassini Solar Wind Campaign in Jan. 2004
Clarke, J. T.; Gérard, Jean-Claude ULg; Grodent, Denis ULg et al

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 ▲]

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See detailAuroral and Non-auroral X-ray Emissions from Jupiter: A Comparative View
Bhardwaj, A.; Elsner, R.; Gladstone, R. et al

Poster (2004)

Jovian X-rays can be broadly classified into two categories: (1) "auroral" emission, which is confined to high-latitudes ( ˜>60° ) at both polar regions, and (2) "dayglow" emission, which originates from ... [more ▼]

Jovian X-rays can be broadly classified into two categories: (1) "auroral" emission, which is confined to high-latitudes ( ˜>60° ) at both polar regions, and (2) "dayglow" emission, which originates from the sunlit low-latitude ( ˜<50° ) regions of the disk (hereafter called "disk" emissions). Recent X-ray observations of Jupiter by Chandra and XMM-Newton have shown that these two types of X-ray emission from Jupiter have different morphological, temporal, and spectral characteristics. In particular: 1) contrary to the auroral X-rays, which are concentrated in a spot in the north and in a band that runs half-way across the planet in the south, the low-latitude X-ray disk is almost uniform; 2) unlike the ˜40±20-min periodic oscillations seen in the auroral X-ray emissions, the disk emissions do not show any periodic oscillations; 3) the disk emission is harder and extends to higher energies than the auroral spectrum; and 4) the disk X-ray emission show time variability similar to that seen in solar X-rays. These differences and features imply that the processes producing X-rays are different at these two latitude regions on Jupiter. We will present the details of these and other features that suggest the differences between these two classes of X-ray emissions from Jupiter, and discuss the current scenario of the production mechanism of them. [less ▲]

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Peer Reviewed
See detailAuroral Precipitation during the Bastille Day Storm Recovery
Immel, T. J.; Mende, S. B.; Frey, H. U. et al

Conference (2001, December 01)

The recovery period following the geomagnetic storm of July 15-16, 2000 is marked by rapid changes in auroral morphology and brightness in the sunlit hemisphere. These observations are made by the FUV and ... [more ▼]

The recovery period following the geomagnetic storm of July 15-16, 2000 is marked by rapid changes in auroral morphology and brightness in the sunlit hemisphere. These observations are made by the FUV and EUV imagers aboard the IMAGE satelite. Clear signatures of magnetospheric convection are observed in the motion of the auroral forms, indicating sunward convection of plasma in the polar cap under the strong northward component of the IMF. Precipitation is also observed equatorward of the auroral oval on the dayside in large diffuse arcs. Unlike previously observed detached proton arcs, this precipitation appears to have a significant electron component. Determination of the characteristic energies and fluxes of electrons and protons requires the proper removal of FUV airglow emissions, which in this case have been strongly affected by the recent magnetic activity. EUV images provide a very clear signature of these events, with practically no airglow contamination. With proper modeling, these EUV images could provide improvements to the characterization of the magnetospheric energy input to the thermosphere and ionosphere from space-based imaging. [less ▲]

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See detailHST Observations of Aurora from the Magnetic Footprints of Io, Ganymede, and Europa during the Millennium Campaign
Clarke, J. T.; Grodent, Denis ULg; Connerney, J. et al

in Bulletin of the American Astronomical Society (2001, November 01)

UV images of Jupiter's aurora obtained with the HST STIS instrument reveal much detail in the distribution of emissions from Io's magnetic footprint on Jupiter, including extended trails of emission in ... [more ▼]

UV images of Jupiter's aurora obtained with the HST STIS instrument reveal much detail in the distribution of emissions from Io's magnetic footprint on Jupiter, including extended trails of emission in the downstream direction. Emissions are also seen from the magnetic footprints of Ganymede and Europa, relatively much fainter and point-like in spatial extent. Knowledge of the statistical properties of these emissions, in terms of their locations and brightnesses, was greatly advanced in a comprehensive series of images obtained during the Millennium campaign in Dec. 2000 - Jan. 2001. These images provide sufficient spatial coverage to give a good indication of the auroral oval locations mapping to Io and Ganymede, and a few points mapping to Europa. The observed variations in footprint properties provide indications of the nature of the electrodynamic interactions of the satellites with Jupiter's magnetic field. These and other indicators also show the direction that magnetic field models should take to better describe Jupiter's internal magnetic field. Contributing evidence comes from the locus of footprint latitudes, and their deviations from the VIP4 model. The latitudinal distance between the Io and Ganymede footprint loci indicates variations in the local field strength, with larger separations corresponding to a weaker field. These separations, and the distance from and distortion of the main oval, indicate an anomalously weak field region in the north near 90[SUP]o[/SUP] longitude. This work has been supported by NASA in STScI grants GO-08171-97A and GO-08657-01A to the University of Michigan. [less ▲]

Detailed reference viewed: 22 (2 ULg)
See detailElectron and Proton Auroral Dynamics
Mende, S. B.; Frey, H. U.; Carlson, C. et al

Conference (2001, May 01)

Data from the IMAGE Wide-band Imaging Camera (WIC),sensitive to far ultraviolet auroras and from the Spectrographic Imager (SI) channel SI12, sensitive to proton precipitation induced Lyman alpha, were ... [more ▼]

Data from the IMAGE Wide-band Imaging Camera (WIC),sensitive to far ultraviolet auroras and from the Spectrographic Imager (SI) channel SI12, sensitive to proton precipitation induced Lyman alpha, were analyzed during a high altitude orbit segment of the IMAGE spacecraft. This segment began during the expansive phase of a substorm. The aurora developed into a double oval configuration, consisting of a set of discrete poleward forms and a separate diffuse auroral oval equatorwards. Although IMF Bz was negative, considerable activity could be seen poleward of the high latitude arcs in the polar cap region. The optical signature of precipitating protons showed that the proton aurora was on the equatorward side of the diffuse aurora and there was a lack of intense energetic proton fluxes in the poleward arcs. A simultaneous FAST pass provided a diagnostic of the particle types in the various regions. These data showed that lower intensity protons were present throughout the entire double oval configuration but with insufficient intensity to produce aurora that could be observed by IMAGE. The FAST data also showed that the bright poleward discrete arcs were accelerated by electrostatic processes, and the wave accelerated electrons were located on the poleward edge of these features. [less ▲]

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Peer Reviewed
See detailThe electron and proton aurora as seen by IMAGE-FUV and FAST
Frey, H. U.; Mende, S. B.; Carlson, C. W. et al

in Geophysical Research Letters (2001), 28

The Far Ultraviolet Instrument (FUV) on the IMAGE spacecraft observes the aurora in three different channels. One of them (SI12) is sensitive to the signal from precipitating protons, while the other two ... [more ▼]

The Far Ultraviolet Instrument (FUV) on the IMAGE spacecraft observes the aurora in three different channels. One of them (SI12) is sensitive to the signal from precipitating protons, while the other two (WIC and SI13) observe auroral emissions which are not only excited by precipitating electrons, but also by protons. We examine a period when in-situ particle measurements by the FAST spacecraft were available simultaneously with global imaging with FUV. The measured electron and proton energy spectra are used to calculate the auroral brightness along the FAST orbit. The comparison with the FUV/IMAGE observations shows good quantitative agreement and demonstrates that under certain circumstances high proton fluxes may produce significant amounts of auroral FUV emission. [less ▲]

Detailed reference viewed: 13 (0 ULg)
Peer Reviewed
See detailGlobal observations of proton and electron auroras in a substorm
Mende, S. B.; Frey, H. U.; Lampton, M. et al

in Geophysical Research Letters (2001), 28

This is the first report of a substorm observed by the IMAGE FUV instruments permitting global observations of electron and proton produced auroras. On the 28th of June 2000 at 1956 UT in the pre-substorm ... [more ▼]

This is the first report of a substorm observed by the IMAGE FUV instruments permitting global observations of electron and proton produced auroras. On the 28th of June 2000 at 1956 UT in the pre-substorm phase at early evening local time the proton aurora was equatorward of the electron precipitation and near midnight they were collocated. There was bright electron and proton aurora in the post midday afternoon side. The sudden brightening of the aurora at substorm onset near midnight is seen in the electrons only although there are protons present at this location. During the expansive phase both the electrons and protons expand poleward. The electron aurora forms a bright surge at the poleward boundary while the protons just show diffuse spreading. The peak intensity of the protons did not change substantially during the entire event. The proton aurora is brighter on the dusk while the electron aurora on the dawn side. As the electron surge expands poleward it leaves the protons behind. The electrons form a discrete auroral feature near the aurora-polar cap boundary, which is devoid of substantial energetic (>1 keV) proton precipitation. The presence of precipitating protons at the point where the initial brightening is seen shows that substorms are initiated on closed field lines. [less ▲]

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See detailA dawn auroral storm on Jupiter: measurement of complex hydocarbons
Clarke, J. T.; Gladstone, R.; Pryor, W. et al

Conference (2000, December)

Detailed reference viewed: 4 (0 ULg)
See detailHST/STIS Observations of a Dawn Auroral Storm on Jupiter
Clarke, J. T.; Gladstone, R.; Pryor, W. et al

in Bulletin of the American Astronomical Society (2000, October 01)

The HST/STIS recorded a detailed time series of images and spectra of the UV emissions from a dawn auroral storm on Jupiter on 21 Sept. 1999. The images show complex and evolving fine structure in the ... [more ▼]

The HST/STIS recorded a detailed time series of images and spectra of the UV emissions from a dawn auroral storm on Jupiter on 21 Sept. 1999. The images show complex and evolving fine structure in the storm, while the emission center remained along the main oval and near dawn in magnetic local time. We serendipitously recorded low resolution UV spectra of the north-south spatial distribution of the auroral emissions. These spectra show far stronger hydrocarbon absorptions than observed in any previous auroral spectra. This indicates an unusually deep penetration of the incident primary particles with respect to the neutral atmosphere, and correspondingly high energy of the primary particles. We can thus use these spectra to identify many complex hydrocarbons in Jupiter's auroral atmosphere which are not normally measured in auroral spectra. These results will be presented along with model fits to the spectra derived both from fitting the observed hydrocarbon absorption features and from comparison with a photochemical model for the expected composition of the auroral atmosphere. This research has been supported by grant GO-8171.01-97A from the Space Telescope Science Institute to the University of Michigan. [less ▲]

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See detailFar ultraviolet imaging from the IMAGE spacecraft. 1. System design
Mende, S. B.; Heetderks, H.; Frey, H. U. et al

in Space Science Reviews (2000), 91

Direct imaging of the magnetosphere by the IMAGE spacecraft will be supplemented by observation of the global aurora, the footprint of magnetospheric regions. To assure the simultaneity of these ... [more ▼]

Direct imaging of the magnetosphere by the IMAGE spacecraft will be supplemented by observation of the global aurora, the footprint of magnetospheric regions. To assure the simultaneity of these observations and the measurement of the magnetospheric background neutral gas density, the IMAGE satellite instrument complement includes three Far Ultraviolet (FUV) instruments. In the wavelength region 120-190 nm, a downward-viewing auroral imager is only minimally contaminated by sunlight, scattered from clouds and ground, and radiance of the aurora observed in a nadir viewing geometry can be observed in the presence of the high-latitude dayglow. The Wideband Imaging Camera (WIC) will provide broad band ultraviolet images of the aurora for maximum spatial and temporal resolution by imaging the LBH N_2 bands of the aurora. The Spectrographic Imager (SI), a monochromatic imager, will image different types of aurora, filtered by wavelength. By measuring the Doppler-shifted Ly-alpha, the proton-induced component of the aurora will be imaged separately. Finally, the GEO instrument will observe the distribution of the geocoronal emission, which is a measure of the neutral background density source for charge exchange in the magnetosphere. The FUV instrument complement looks radially outward from the rotating IMAGE satellite and, therefore, it spends only a short time observing the aurora and the Earth during each spin. Detailed descriptions of the WIC, SI, GEO, and their individual performance validations are discussed in companion papers. This paper summarizes the system requirements and system design approach taken to satisfy the science requirements. One primary requirement is to maximize photon collection efficiency and use efficiently the short time available for exposures. The FUV auroral imagers WIC and SI both have wide fields of view and take data continuously as the auroral region proceeds through the field of view. To minimize data volume, multiple images are taken and electronically co-added by suitably shifting each image to compensate for the spacecraft rotation. In order to minimize resolution loss, the images have to be distortion-corrected in real time for both WIC and SI prior to co-adding. The distortion correction is accomplished using high speed look up tables that are pre-generated by least square fitting to polynomial functions by the on-orbit processor. The instruments were calibrated individually while on stationery platforms, mostly in vacuum chambers as described in the companion papers. Extensive ground-based testing was performed with visible and near UV simulators mounted on a rotating platform to estimate their on-orbit performance. The predicted instrument system performance is summarized and some of the preliminary data formats are shown. [less ▲]

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