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SWAN/SOHO H Cell Measurements: The First Year
Bertaux, Jean-Loup; Lallement, Rosine; Quémerais, Eric +3 more
We present here an analysis of one year of data obtained by the SWAN instrument on board the SOHO spacecraft orbiting around the L1 Lagrange point at 1.5 × 106 km sunward from Earth. This instrument is measuring the interplanetary Lyman ca background due to solar photons backscattered by hydrogen atoms in the interplanetary medium. The …
Surface and Sub-surface Electrical Measurement of Titan with the PWA-HASI Experiment on Huygens
Rodrigo, R.; López-Moreno, J. J.; Fulchignoni, M. +11 more
The Permittivity Waves and Altimetry (PWA) experiment is part of the Huygens Atmospheric Structure Instrument (HASI) presently `en route' toTitan as a part of the HUYGENS Probe carried by the Saturn orbiter CASSINI. When HUYGENS lands upon Titan, the Mutual Impedance (MI) probe, part of the PWA experiment will be set to a special mode to measure t…
Large-Scale Evolution of the Active Region NOAA 7978, 7981, 7986 Observed by Goes, Soho, and Yohkoh
van Driel-Gesztelyi, L.; Foing, B.; Fludra, A. +3 more
We took part in a joint project aimed to study the large-scale evolution of an active region from its emergence throughout its decay for several solar rotations. Our interest focuses on the understanding of how energy is generated, released, deposited, and transformed in active regions. To this end, we determined physical parameters like intensity…
Coronal Mass Ejections and the Solar Wind: New Results from LASCO
Howard, R. A.; Dere, K. P.; Brueckner, G. E.
The LASCO and EIT experiments on SOHO have provided a revolutionary picture of coronal dynamics. In the past, the corona has largely been thought to be a region where the evolution of the coronal structures occurred on relatively large time scales, aside from the intermittent coronal mass ejection. The outflows in the polar coronal holes were larg…
Non-Radial Unipolar Coronal Streamers in Magnetically High Latitudes and Radial Bipolar Streamers at the Magnetic Equator of the Sun
Shibata, K.; Dere, K. P.; Saito, Takao +1 more
The complex structure of coronal streamers can be better understood by their classification into two classes: non-radial unipolar streamers emanating from magnetically high latitudes, and radial bipolar streamers emanating from the magnetic equator. The coronal streamers observed during the total solar eclipses of July 11,1991 and February 26, 199…
Comparisons of Interplanetary Scintillation and Optical Measurements of Solar Wind Acceleration with Model Results
Thompson, B. J.; Breen, A. R.; de Forest, C. F. +4 more
Observations of the fast, high latitude solar wind show that acceleration of the fast wind is complete by 10 solar radii (R), while measurements from the LASCO instrument on SOHO show that most of the acceleration takes place inside 5 R. A series of observations were made in September 1997 using EISCAT and the C2 and C3 coronagraphs aboard SOHO to…
Energetic Particle Signatures of a Corotating Interaction Region from a High Latitude Coronal Hole: SOHO, Wind and Ulysses Observations
Thompson, B. J.; Lazarus, A. J.; Kunow, H. +10 more
In mid 1996 the Comprehensive Suprathermal and Energetic Particle Analyser (COSTEP) onboard the Solar and Heliospheric Observatory, at 1 AU in the ecliptic plane, detected recurrent periods of enhanced MeV ions in association with a corotating interaction region (CIR). Measurements of energetic ions from the Cosmic Ray and Solar Particle Instrumen…
Cluster II: Plasma Measurements in Three Dimensions
Escoubet, C. P.; Schmidt, R.
After the dramatic accident of the first Ariane 5 rocket on 4 June 1996, causing the loss of the four European Space Agency's Cluster spacecraft, a recovery programme was initiated. During 10 months, alternative studies and intense negotiations were conducted with industry, and on 3 April 1997, the ESA Science Programme Committee agreed on the re-…
Signatures of Magnetic Reconnection and Observed EUV Emission Line Profiles in An Active Region
Wilhelm, K.; Kjeldseth-Moe, O.; Brekke, P. +2 more
We report on observations with SUMER on SOHO of high-velocity events, also called explosive events. The high spatial and spectral resolutions of SUMER allow simultaneous observations of EUV emission lines formed at different temperatures within the transition region. Complex line profiles with three separate line components appear to be a characte…
Sumer Observations of the Quiet Sun: Transition Region and Low Corona
Wilhelm, Klaus
SUMER - the Solar Ultraviolet Measurements of Emitted Radiation instrument on the Solar and Helio-spheric Observatory (SOHO) of ESA and NASA - observed its first light on January 24, 1996 and covered the minimum of the sunspot activty between the solar cycles 22 and 23 with nearly continuous observations. Consequently, in many studies particular e…