References of "Gérard, Jean-Claude"
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See detailNightglow investigation in the Visible Range with the VIRTIS/Venus-Express instrument
Migliorini, A.; Slanger, T.; Saran, D. et al

Poster (2011, December)

In this study we report the investigation of the nightglow molecular oxygen emissions of Venus in the visible spectral range, observed by the VIRTIS instrument (Visible and InfraRed Spectral Imaging ... [more ▼]

In this study we report the investigation of the nightglow molecular oxygen emissions of Venus in the visible spectral range, observed by the VIRTIS instrument (Visible and InfraRed Spectral Imaging Spectrometer) on board the Venus Express spacecraft. The Herzberg II system was detected in the range 0.4-0.7 µm. The observed bands peak at 95-96 km altitude, with a limb mode intensity of 15-20 kR for the strongest band, similar to that seen in previous observations. Simultaneous observations in the visible and IR [O2 (a-X) 1.27 µm band] were obtained in March 2007, and the two systems are similar in peak altitude. In addition, three bands of the O2 Chamberlain system, at 0.558, 0.604, and 0.657 µm were detected. They are well detached from the Herzberg II bands, and more distinct than reported in previous observations (Garcia Munoz et al., 2009). A simulated spectrum is obtained using the DIATOM code, allowing accurate reproduction of the observed VIRTIS mean spectrum. [less ▲]

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See detailOn the origin of the 2-3 minutes quasi-periodicity in the Jovian magnetosphere
Bonfond, Bertrand ULg; Vogt, Marissa F.; Gérard, Jean-Claude ULg et al

Poster (2011, October 05)

Several kinds of periodicities have been observed at Jupiter since the first probes fly-by. However, pre- vious investigations mainly focused on the longer timescales, such as the 40 minutes (QP40) or the ... [more ▼]

Several kinds of periodicities have been observed at Jupiter since the first probes fly-by. However, pre- vious investigations mainly focused on the longer timescales, such as the 40 minutes (QP40) or the 2- 3 days quasi-periodicity. Here we describe the recent finding of the 2-3 minutes quasi-periodic occurrence of UV flares in the active region of the polar aurora. These observations are then compared to other measurements of such quasi-periodic behaviors in electron and magnetic field data and their probably common origin is discussed. [less ▲]

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See detailMeasurements of the helium 584 Å airglow during the Cassini flyby of Venus
Gérard, Jean-Claude ULg; Gustin, Jacques ULg; Hubert, Benoît ULg et al

in Planetary and Space Science (2011), 59

The helium resonance line at 584 Å has been observed with the UltraViolet Imaging Spectrograph (UVIS) Extreme Ultraviolet channel during the flyby of Venus by Cassini at a period of high solar activity ... [more ▼]

The helium resonance line at 584 Å has been observed with the UltraViolet Imaging Spectrograph (UVIS) Extreme Ultraviolet channel during the flyby of Venus by Cassini at a period of high solar activity. The brightness was measured along the disk from the morning terminator up to the bright limb near local noon. The mean disk intensity was ˜320 R, reaching ˜700 R at the bright limb. These values are slightly higher than those determined from previous observations. The sensitivity of the 584 Å intensity to the helium abundance is analyzed using recent cross-sections and solar irradiance measurements at 584 Å. The intensity distribution along the UVIS footprint on the disk is best reproduced using the EUVAC solar flux model and the helium density distribution from the VTS3 empirical model. It corresponds to a helium density of 8×10[SUP]6[/SUP] cm[SUP]-3[/SUP] at the level of where the CO[SUB]2[/SUB] is 2×10[SUP]10[/SUP] cm[SUP]-3[/SUP]. [less ▲]

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See detailThe energy the auroral electrons in Saturn's atmosphere : remote sensing and thermal consequences
Gérard, Jean-Claude ULg; Gustin, Jacques ULg; Grodent, Denis ULg et al

Poster (2011, October)

Saturn’s north aurora has been observed between January and May 2011 with the Hubble Space Telescope. The objective was to collect spatially resolved spectra at the different local time from dawn to dusk ... [more ▼]

Saturn’s north aurora has been observed between January and May 2011 with the Hubble Space Telescope. The objective was to collect spatially resolved spectra at the different local time from dawn to dusk and compare them with laboratory or synthetic spectra. For this purpose, HST was programmed to slew from mid-latitudes through the auroral oval up to above the limb while collecting data in the timetag mode. The spectra show signatures of absorption by hydrocarbons present above the peak of the auroral emission. The amount of absorption and implications in terms of penetration of the auroral electron beam into Saturn’s atmosphere will be discussed and compared with other determinations of the altitude of the aurora. The effects of the auroral heat import on the thermal structure of the atmosphere both at high and low altitudes will be examined in the light of these results. [less ▲]

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See detailThe Venus visible oxygen nightglow with VIRTIS on board Venus Express
Migliorini, A.; Piccioni, G.; Gérard, Jean-Claude ULg et al

Scientific conference (2011, October)

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See detailDetection of Auroral Emissions from Callisto’s Magnetic Footprint at Jupiter
Clarke, J. T.; Wannawichian, S.; Hernandez, N. et al

Poster (2011, October)

HST observations of Jupiter’s aurora in a large campaign reveal several cases where the main oval emission appeared at unusually low latitudes, making it possible to search for the first time for auroral ... [more ▼]

HST observations of Jupiter’s aurora in a large campaign reveal several cases where the main oval emission appeared at unusually low latitudes, making it possible to search for the first time for auroral emissions from the magnetic footprint of Callisto without the overlapping bright emissions from the main oval. Several cases have been found where point-source emissions have now been detected from locations consistent with Callisto’s magnetic footprint on Jupiter at a brightness of ten’s of kilo- Rayleighs. These observations confirm that there is an electrodynamic interaction between Callisto and Jupiter’s magnetospheric environment that is similar to those at Io, Europa, and Ganymede, which all have auroral footprints. The properties of the emissions and a comparison with other observations and theoretical expectations will be presented in this paper. [less ▲]

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See detailThe OH Venus nightglow : morphology and relation to ozone in the upper atmosphere
Soret, Lauriane ULg; Gérard, Jean-Claude ULg; Piccioni, G. et al

Conference (2011, October)

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See detailJUDE: A Far-UV Imager for JUICE
Grodent, Denis ULg; Bunce, Emma; Bannister, Nigel et al

Poster (2011, August 31)

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See detailUnderstanding the variability of nightside temperatures, NO UV and O2 IR nightglow emissions in the Venus upper atmosphere
Brecht, A. S.; Bougher, S. W.; Gérard, Jean-Claude ULg et al

in Journal of Geophysical Research. Planets (2011), 116

Venus Express (VEX) has been monitoring key nightglow emissions and thermal features (O[SUB]2[/SUB] IR nightglow, NO UV nightglow, and nightside temperatures) which contribute to a comprehensive ... [more ▼]

Venus Express (VEX) has been monitoring key nightglow emissions and thermal features (O[SUB]2[/SUB] IR nightglow, NO UV nightglow, and nightside temperatures) which contribute to a comprehensive understanding of the global dynamics and circulation patterns above ˜90 km. The nightglow emissions serve as effective tracers of Venus' middle and upper atmosphere global wind system due to their variable peak brightness and horizontal distributions. A statistical map has been created utilizing O[SUB]2[/SUB] IR nightglow VEX observations, and a statistical map for NO UV is being developed. A nightside warm layer near 100 km has been observed by VEX and ground-based observations. The National Center for Atmospheric Research (NCAR) Venus Thermospheric General Circulation Model (VTGCM) has been updated and revised in order to address these key VEX observations and to provide diagnostic interpretation. The VTGCM is first used to capture the statistically averaged mean state of these three key observations. This correspondence implies a weak retrograde superrotating zonal flow (RSZ) from ˜80 km to 110 km and above 110 km the emergence of modest RSZ winds approaching 60 m s[SUP]-1[/SUP] above ˜130 km. Subsequently, VTGCM sensitivity tests are performed using two tuneable parameters (the nightside eddy diffusion coefficient and the wave drag term) to examine corresponding variability within the VTGCM. These tests identified a possible mechanism for the observed noncorrelation of the O[SUB]2[/SUB] and NO emissions. The dynamical explanation requires the nightglow layers to be at least ˜15 km apart and the retrograde zonal wind to increase dramatically over 110 to 130 km. [less ▲]

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See detailUV-IR comparison: Jupiter aurora
Gérard, Jean-Claude ULg; Grodent, Denis ULg

Conference (2011, August)

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See detailThe Ultraviolet Spectrograph (UVS) on Juno
Gladstone, G. R.; Persyn, S.; Eterno, J. et al

Poster (2011, July 11)

Detailed reference viewed: 32 (5 ULg)
See detailCassini UVIS Observations of Varying Auroral Emissions on Saturn's Night Side
Pryor, W.; Esposito, L.; Jouchoux, A. et al

Poster (2011, July 11)

Detailed reference viewed: 11 (3 ULg)
See detailAuroral signatures of injections in the magnetosphere of Saturn
Radioti, Aikaterini ULg; Roussos, E.; Grodent, Denis ULg et al

Poster (2011, July 11)

Detailed reference viewed: 22 (12 ULg)
See detailInside the Jupiter Main Auroral Emissions: Flares, Spots, Arc...and Satellite Footprints?
Bonfond, Bertrand ULg; Vogt, M. F.; Yoneda, M. et al

Conference (2011, July 11)

Detailed reference viewed: 22 (11 ULg)
See detailThe multiple spots of the Ganymede footprint
Bonfond, Bertrand ULg; Hess, S.; Grodent, Denis ULg et al

Poster (2011, July 11)

Detailed reference viewed: 15 (7 ULg)
See detailAurora : Global features
Gérard, Jean-Claude ULg

Conference (2011, July)

Detailed reference viewed: 5 (1 ULg)