We have fabricated a diamond-turned low-mass version of a toroidal mirror which is a key element for a spaceborne
visible-light heliospheric imager. This mirror's virtual image of roughly a hemisphere of sky is viewed by a conventional
photometric camera. The optical system views close to the edge of an external protective baffle and does not protrude
from the protected volume. The sky-brightness dynamic range and background-light rejection requires minimal wideangle
scattering from the mirror surface. We describe the manufacturing process for this mirror, and present preliminary
laboratory measurements of its wide-angle scattering characteristics.
White-light Thomson scattering observations from the Solar Mass Ejection Imager (SMEI) have recorded the
inner heliospheric response to many CMEs. Some of these are also observed from the LASCO
instrumentation and, most recently, the STEREO spacecraft. Here, we detail several CME events in SMEI
observations that have also been observed by the LASCO instrumentation and STEREO spacecrafts. We
show how SMEI is able to measure CME events from their first observations as close as 20° from the solar
disk until they fade away in the SMEI 180° field of view. We employ a 3D reconstruction technique that
provides perspective views as observed from Earth, from outward-flowing solar wind. This is accomplished
by iteratively fitting the parameters of a kinematic solar wind density model to the SMEI white-light
observations and, where possible, including interplanetary scintillation (IPS) velocity data. This 3D modeling
technique enables separating the true heliospheric response in SMEI from background noise, and
reconstructing the 3D heliospheric structure as a function of time. These reconstructions allow both
separation of CME structure from other nearby heliospheric features and a determination of CME mass.
Comparisons with LASCO and STEREO images for individual CMEs or portions of them allow a detailed
view of changes to the CME shape and mass as they propagate outward.
KEYWORDS: Solar processes, 3D modeling, Solar radiation models, Tomography, Data modeling, Scintillation, Kinematics, Sun, Radar, 3D image reconstruction
The technique of interplanetary scintillation (IPS) can be used to probe interplanetary space between the Sun and Earth
most-commonly in terms of speed and also by using the scintillation-level (g-level) as a proxy for density. We combine
the large spatial-scale 3D tomographic techniques previously only applied to IPS data from the Solar Terrestrial Environment
Laboratory (STELab) array, Nagoya University in Japan, and the previously operational Cambridge IPS system in
England, with the finer-scale capabilities of the longer baselines between the systems of the Multi-Element Radio-Linked
Interferometer Network (MERLIN) in the UK, and the European Incoherent SCATter (EISCAT) radar and the EISCAT
Svalbard Radar (ESR) in northern Scandinavia. Using the UCSD 3D reconstruction technique, we present results of detailed
measurements of speed in the solar wind and also those of solar wind flow-directions, constrained by the large-scale
density tomography through the use of a kinematic model, as well as applying this tomographic technique for the first time
to the MERLIN, EISCAT, and ESR IPS solar wind speed observations in terms of velocity.
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