Search Publications
Optimal filtering of solar images using soft morphological processing techniques
Fletcher, L.; Marshall, S.; Hough, K.
Context: .CCD images obtained by space-based astronomy and solar physics are frequently spoiled by galactic and solar cosmic rays, and particles in the Earth's radiation belt, which produces an overlaid, often saturated, speckle.
Aims: .We describe the development and application of a new image-processing technique for the removal of this nois…
Why are there stationary EIT wave fronts
Chen, P. F.; Shibata, K.; Fang, C.
EIT waves are often observed to be propagating EUV enhancements followed by an expanding dimming region after the launch of CMEs. It was widely assumed that they are the coronal counterparts of the chromospheric Moreton waves, though the former are three or more times slower. The existence of a stationary “EIT wave” front in some events, however, …
Exploration of Mars in SPICAM-IR experiment onboard the Mars-Express spacecraft: 1. Acousto-optic spectrometer SPICAM-IR
Gondet, B.; Dimarellis, E.; Reberac, A. +12 more
The acousto-optic spectrometer of the near infrared range, which is a part of the spectrometer SPICAM onboard the Mars-Express spacecraft, began to operate in the orbit of Mars in January 2004. In the SPICAM experiment, a spectrometer on the basis of an acousto-optic filter was used for the first time to investigate other planets. During one and a…
Results of measurements with the Planetary Fourier Spectrometer onboard Mars Express: Clouds and dust at the end of southern summer. A comparison with OMEGA images
Bibring, J. -P.; Bellucci, G.; Altieri, F. +22 more
We discuss the results of measurements made with the Planetary Fourier Spectrometer (PFS) onboard the Mars Express spacecraft. The data were obtained in the beginning of the mission and correspond to the end of summer in the southern hemisphere of Mars ( L s ∼ 340°). Three orbits are considered, two of which passed through volcanoes O…
Planetary science: Titan's exotic weather
Griffith, Caitlin A.
Titan is viewed as a sibling of Earth, as both bodies have rainy weather systems and landscapes formed by rivers. But as we study these similarities, Titan emerges as an intriguingly foreign world.
EUV line intensity distribution in the solar atmosphere: differences between a polar coronal hole and its equatorial extension
Raju, K. P.; Bromage, B. J. I.
Intensity histograms of 14 EUV emission lines in a polar coronal hole, its equatorial extension, the "Elephant's Trunk", and the adjacent quiet Sun regions have been obtained from SOHO/CDS observations made in August and September 1996. Differences between the quiet region and coronal hole on the one hand, and the polar hole and the equatorial ext…
Imaging techniques for gamma-ray diffuse emission: application to INTEGRAL/SPI
Roques, J. -P.; Allain, M.
Diffuse imaging in the gamma-ray energy range is a challenging problem, since faint radiation is usually mixed with strong instrumental background components. This situation results in data sets that are not very informative, so they lead to non robust image reconstruction. In this paper, we used a Bayesian approach to produce sky-maps with high r…
Top layers charaterization of the Martian surface: Permittivity estimation based on geomorphology analysis
Kofman, W.; Herique, A.; Nouvel, J. -F. +1 more
Mars Express spacecraft inserted successfully Martian orbit at the end of 2003. On board this probe, a radar instrument called MARSIS (for Mars Advanced Radar for Surface and Ionosphere Sounding) is looking for water inside the first kilometers of Martian crust. To support MARSIS planning and data inversion, Laboratoire de Planétologie de Grenoble…
From Hubble diagrams to scale factors
Tilquin, A.; Schücker, T.
Context: .
Aims: .We study the image of the transform from scale parameters to Hubble diagrams and present a lower bound on the radius of the universe today a0 and a monotonicity constraint on the Hubble diagram.
Methods: .Our theoretical input is minimal: Einstein's kinematics and maximally symmetric universes.
Results: .Pr…
Determination of local surface properties using Mars Express bistatic radar
Tyler, G. Leonard; Pätzold, Martin; Häusler, Bernd +1 more
Dual-frequency bistatic radar experiments were conducted with Mars Express at a rate of one to two per month during 2005. Each observation provided power measurements of orthogonally polarized surface echoes at one specular point; the ratio of these components yielded values of the dielectric constant in the range 2.0 < $\varepsilon$ < 4.0. …