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See detailThe solar orbiter imager (SoloHI) instrument for the Solar Orbiter mission
Howard, R. A.; Vourlidas, A.; Korendyke, C. M. et al

in Proceedings of SPIE - The International Society for Optical Engineering (2013)

The SoloHI instrument for the ESA/NASA Solar Orbiter mission will track density fluctuations in the inner heliosphere, by observing visible sunlight scattered by electrons in the solar wind. Fluctuations ... [more ▼]

The SoloHI instrument for the ESA/NASA Solar Orbiter mission will track density fluctuations in the inner heliosphere, by observing visible sunlight scattered by electrons in the solar wind. Fluctuations are associated with dynamic events such as coronal mass ejections, but also with the “quiescent” solar wind. SoloHI will provide the crucial link between the low corona observations from the Solar Orbiter instruments and the in-situ measurements on Solar Orbiter and the Solar Probe Plus missions. The instrument is a visible-light telescope, based on the SECCHI/Heliospheric Imager (HI) currently flying on the STEREO mission. In this concept, a series of baffles reduce the scattered light from the solar disk and reflections from the spacecraft to levels below the scene brightness, typically by a factor of 1012. The fluctuations are imposed against a much brighter signal produced by light scattered by dust particles (the zodiacal light/F-corona). Multiple images are obtained over a period of several minutes and are summed on-board to increase the signal-to-noise ratio and to reduce the telemetry load. SoloHI is a single telescope with a 40⁰ field of view beginning at 5° from the Sun center. Through a series of Venus gravity assists, the minimum perihelia for Solar Orbiter will be reduced to about 60 Rsun (0.28 AU), and the inclination of the orbital plane will be increased to a maximum of 35° after the 7 year mission. The CMOS/APS detector is a mosaic of four 2048 x 1930 pixel arrays, each 2-side buttable with 11 μm pixels. [less ▲]

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See detailSeeing the corona with the solar probe plus mission: the wide-field imager for solar probe+ (WISPR)
Vourlidas, A.; Howard, R. A.; Plunkett, S. P. et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2013)

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See detailTonabersat, a gap-junction modulator: efficacy and safety in two randomized, placebo-controlled, dose-ranging studies of acute migraine.
Silberstein, S. D.; Schoenen, Jean ULg; Gobel, H. et al

in Cephalalgia : An International Journal of Headache (2009), 29 Suppl 2

Tonabersat is a novel benzopyran derivative that blocks the cortical spreading depression proposed to be associated with migraine attacks. The ability of single oral doses of 15, 25, 40 and 80 mg of ... [more ▼]

Tonabersat is a novel benzopyran derivative that blocks the cortical spreading depression proposed to be associated with migraine attacks. The ability of single oral doses of 15, 25, 40 and 80 mg of tonabersat to relieve the symptoms of moderate to severe migraine was evaluated in 859 migraineurs enrolled in two dose-ranging, double-blind, randomized, placebo-controlled, parallel-group trials, one international and the other North American. In the international study, significantly more patients given tonabersat than given placebo experienced relief of headache pain at 2 h (15 mg, 36.8%; 40 mg, 40.7%), the principal efficacy variable, and at 4 h (40 mg, 63.0%) and complete abolition of headache at 4 h (40 mg, 34.3%). None of the primary or secondary efficacy variables indicated significant differences between tonabersat and placebo in the North American study. Tonabersat was generally well tolerated, with dizziness and nausea the most common side-effects. Serious adverse events were uncommon, and no patient withdrew from either study because of adverse events. These results suggest a possible interplay between tonabersat pharmacokinetics (the relatively long time required to reach maximum plasma concentrations) and patient characteristics (previous triptan exposure) in the management of acute migraine attacks. Based on the pharmacokinetics and actions on cortical spreading depression, tonabersat may have potential value in migraine prophylaxis. [less ▲]

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See detailSun Earth Connection Coronal and Heliospheric Investigation (SECCHI)
Howard, R. A.; Moses, J. D.; Vourlidas, A. et al

in Space Science Reviews (2008), 136

The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) is a five telescope package, which has been developed for the Solar Terrestrial Relation Observatory (STEREO) mission by the Naval ... [more ▼]

The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) is a five telescope package, which has been developed for the Solar Terrestrial Relation Observatory (STEREO) mission by the Naval Research Laboratory (USA), the Lockheed Solar and Astrophysics Laboratory (USA), the Goddard Space Flight Center (USA), the University of Birmingham (UK), the Rutherford Appleton Laboratory (UK), the Max Planck Institute for Solar System Research (Germany), the Centre Spatiale de Leige (Belgium), the Institut d'Optique (France) and the Institut d'Astrophysique Spatiale (France). SECCHI comprises five telescopes, which together image the solar corona from the solar disk to beyond 1 AU. These telescopes are: an extreme ultraviolet imager (EUVI: 1 1.7 R[SUB]o[/SUB]), two traditional Lyot coronagraphs (COR1: 1.5 4 R[SUB]o[/SUB] and COR2: 2.5 15 R[SUB]o[/SUB]) and two new designs of heliospheric imagers (HI-1: 15 84 R[SUB]o[/SUB] and HI-2: 66 318 R[SUB]o[/SUB]). All the instruments use 2048×2048 pixel CCD arrays in a backside-in mode. The EUVI backside surface has been specially processed for EUV sensitivity, while the others have an anti-reflection coating applied. A multi-tasking operating system, running on a PowerPC CPU, receives commands from the spacecraft, controls the instrument operations, acquires the images and compresses them for downlink through the main science channel (at compression factors typically up to 20×) and also through a low bandwidth channel to be used for space weather forecasting (at compression factors up to 200×). An image compression factor of about 10× enable the collection of images at the rate of about one every 2 3 minutes. Identical instruments, except for different sizes of occulters, are included on the STEREO-A and STEREO-B spacecraft. [less ▲]

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See detailDiscovery of the atomic iron tail of comet McNaught using the Heliospheric Imager on STEREO
Fulle, M.; Leblanc, F.; Harrison, R. A. et al

in Astrophysical Journal (2007), 661(1, Part 2), 93-96

In 2007 January, at the heliocentric distance r < 0.3 AU, comet McNaught 2006P1 became the brightest comet since C/Ikeya-Seki 1965S1 and was continuously monitored by space-based solar observatories. We ... [more ▼]

In 2007 January, at the heliocentric distance r < 0.3 AU, comet McNaught 2006P1 became the brightest comet since C/Ikeya-Seki 1965S1 and was continuously monitored by space-based solar observatories. We provide strong evidence that an archlike tail observed by the Heliospheric Imager aboard the STEREO spacecraft is the first ever detected tail composed of neutral Fe atoms. We obtain an Fe lifetime tau = (4.1 +/- 0.4) x 10(4) s at r = 0.25 AU, in agreement with theoretical predictions of the photoionization lifetime. The expected dust temperature is inconsistent with iron sublimation, suggesting that Fe atoms are coming from troilite evaporation. [less ▲]

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See detailMAGRITTE / SPECTRE : the Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory
Rochus, Pierre ULg; Defise, Jean-Marc ULg; Halain, Jean-Philippe ULg et al

in AGU Fall Meeting Abstracts (2002), 21

The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory will characterize the dynamical evolution of the solar plasma from the chromosphere to the corona, and will follow the ... [more ▼]

The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory will characterize the dynamical evolution of the solar plasma from the chromosphere to the corona, and will follow the connection of plasma dynamics with magnetic activity throughout the solar atmosphere. The AIA consists of 7 high resolution imaging telescopes in the following spectral bandpasses: 1215 \x8F Ly-a, 304 \x8F He II, 629 \x8F OV, 465 \x8F Ne VII, 195 \x8F Fe XII (includes Fe XXIV), 284 \x8F Fe XV, and 335 \x8F Fe XVI. The telescopes are grouped by instrumental approach: the Magritte Filtergraphs (R. Magritte, famous 20th Century Belgian Surrealistic Artist), five multilayer EUV channels with bandpasses ranging from 195 to 1216 \x8F, and the SPECTRE Spectroheliograph with one soft-EUV channel at OV 629 \x8F. They will be simultaneously operated with a 10-second imaging cadence. These two instruments, the electronic boxes and two redundant Guide Telescopes (GT) constitute the AIA suite. They will be mounted and coaligned on a dedicated common optical bench. The GTs will provide pointing jitter information to the whole SHARPP assembly. This poster presents the selected technologies, the different challenges, the trade-offs to be made in phase A, and the model philosophy. From a scientific viewpoint, the unique combination high temporal and spatial resolutions with the simultaneous multi-channel capability will allow Magritte/SPECTRE to explore new domains in the dynamics of the solar atmosphere, in particular the fast small-scale phenomena. We show how the spectral channels of the different instruments were derived to fulfill the AIA scientific objectives, and we outline how this imager array will address key science issues, like the transition region and coronal waves or flare precursors, in coordination with other SDO experiments. We finally describe the real-time solar monitoring products that will be made available for space-weather forecasting applications. [less ▲]

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See detailObservations of Coronal Structures Above an Active Region by EIT and Implications for Coronal Energy Deposition
Neupert, W. M.; Newmark, J.; Delaboudinière, J.-P. et al

in Solar Physics (1998), 183

Solar EUV images recorded by the EUV Imaging Telescope (EIT) on SOHO have been used to evaluate temperature and density as a function of position in two largescale features in the corona observed in the ... [more ▼]

Solar EUV images recorded by the EUV Imaging Telescope (EIT) on SOHO have been used to evaluate temperature and density as a function of position in two largescale features in the corona observed in the temperature range of 1.0-2.0MK. Such observations permit estimates of longitudinal temperature gradients (if present) in the corona and, consequently, estimates of thermal conduction and radiative losses as a function of position in the features. We examine two relatively cool features as recorded in EIT's Feix/x (171Å) and Fexii (195Å) bands in a decaying active region. The first is a long-lived loop-like feature with one leg, ending in the active region, much more prominent than one or more distant footpoints assumed to be rooted in regions of weakly enhanced field. The other is a near-radial feature, observed at the West limb, which may be either the base of a very high loop or the base of a helmet streamer. We evaluate energy requirements to support a steady-state energy balance in these features and find in both instances that downward thermal conductive losses (at heights above the transition region) are inadequate to support local radiative losses, which are the predominant loss mechanism. The requirement that a coronal energy deposition rate proportional to the square of the ambient electron density (or pressure) is present in these cool coronal features provides an additional constraint on coronal heating mechanisms. [less ▲]

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See detailEIT and LASCO Observations of the Initiation of a Coronal Mass Ejection
Dere, K. P.; Brueckner, G. E.; Howard, R. A. et al

in Solar Physics (1997), 175

We present the first observations of the initiation of a coronal mass ejection (CME) seen on the disk of the Sun. Observations with the EIT experiment on SOHO show that the CME began in a small volume and ... [more ▼]

We present the first observations of the initiation of a coronal mass ejection (CME) seen on the disk of the Sun. Observations with the EIT experiment on SOHO show that the CME began in a small volume and was initially associated with slow motions of prominence material and a small brightening at one end of the prominence. Shortly afterward, the prominence was accelerated to about 100 km s[SUP]-1[/SUP] and was preceded by a bright loop-like structure, which surrounded an emission void, that traveled out into the corona at a velocity of 200 400 km s[SUP]-1[/SUP]. These three components, the prominence, the dark void, and the bright loops are typical of CMEs when seen at distance in the corona and here are shown to be present at the earliest stages of the CME. The event was later observed to traverse the LASCO coronagraphs fields of view from 1.1 to 30 Ro. Of particular interest is the fact that this large-scale event, spanning as much as 70 deg in latitude, originated in a volume with dimensions of roughly 35" (2.5 x 10[SUP]4[/SUP] km). Further, a disturbance that propagated across the disk and a chain of activity near the limb may also be associated with this event as well as a considerable degree of activity near the west limb. [less ▲]

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See detailEIT Observations of the Extreme Ultraviolet Sun
Moses, D.; Clette, Frédéric; Delaboudinière, J.-P. et al

in Solar Physics (1997), 175

The Extreme Ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft has been operational since 2 January 1996. EIT observes the Sun over a 45 x 45 arc min field of view in four emission line ... [more ▼]

The Extreme Ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft has been operational since 2 January 1996. EIT observes the Sun over a 45 x 45 arc min field of view in four emission line groups: Feix, x, Fexii, Fexv, and Heii. A post-launch determination of the instrument flatfield, the instrument scattering function, and the instrument aging were necessary for the reduction and analysis of the data. The observed structures and their evolution in each of the four EUV bandpasses are characteristic of the peak emission temperature of the line(s) chosen for that bandpass. Reports on the initial results of a variety of analysis projects demonstrate the range of investigations now underway: EIT provides new observations of the corona in the temperature range of 1 to 2 MK. Temperature studies of the large-scale coronal features extend previous coronagraph work with low-noise temperature maps. Temperatures of radial, extended, plume-like structures in both the polar coronal hole and in a low latitude decaying active region were found to be cooler than the surrounding material. Active region loops were investigated in detail and found to be isothermal for the low loops but hottest at the loop tops for the large loops. [less ▲]

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See detailFirst Results from EIT
Clette, Frédéric; Delaboudiniere, J.-P.; Artzner, G. E. et al

in 1st Advances in Solar Physics Euroconference. Advances in Physics of Sunspots (1997)

The Extreme-UV Imaging telescope has already produced more than 15000 wide-field images of the corona and transition region, on the disk and up to 1.5R_o above the limb, with a pixel size of 2.6\arcsec ... [more ▼]

The Extreme-UV Imaging telescope has already produced more than 15000 wide-field images of the corona and transition region, on the disk and up to 1.5R_o above the limb, with a pixel size of 2.6\arcsec. By using four different emission lines, it provides the global temperature distribution in the quiet corona, in the range 0.5 to 3*E(6) K. Its excellent sensitivity and wide dynamic range allow unprecedented views of low emission features, even inside coronal holes. Those so-called ``quiet'' regions actually display a wide range of dynamical phenomena, in particular at small spatial scales and at time scales going down to only a few seconds, as revealed by all EIT time sequences of full- or partial-field images. The initial results presented here demonstrate the importance of this wide-field imaging experiment for a good coordination between SOHO and ground-based solar telescopes, as well as for science planning. [less ▲]

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See detailImaging the solar corona in the EUV
Delaboudiniere, J.-P.; Stern, R. A.; Maucherat, A. et al

in Advances in Space Research (1997), 20

The SOHO (SOlar and Heliospheric Observatory) satellite was launched on December 2nd 1995. After arriving at the Earth-Sun (L1) Lagrangian point on February 14th 1996, it began to continuously observe the ... [more ▼]

The SOHO (SOlar and Heliospheric Observatory) satellite was launched on December 2nd 1995. After arriving at the Earth-Sun (L1) Lagrangian point on February 14th 1996, it began to continuously observe the Sun. As one of the instruments onboard SOHO, the EIT (Extreme ultraviolet Imaging Telescope) images the Sun's corona in 4 EUV wavelengths. The He II filter at 304 AË images the chromosphere and the base of the transition region at a temperature of 5 - 8 x 10^4 K; the Fe IX-X filter at 171 AË images the corona at a temperature of ~ 1.3 x 10^6 K; the Fe XII filter at 195 AË images the quiet corona outside coronal holes at a temperature of ~ 1.6 x 10^6 K; and the Fe XV filter at 284 AË images active regions with a temperature of ~ 2.0 x 10^6 K. About 5000 images have been obtained up to the present. In this paper, we describe also some aspects of the telescope and the detector performance for application in the observations. Images and movies of all the wavelengths allow a look at different phenomena present in the Sun's corona, and in particular, magnetic field reconnection. [less ▲]

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See detailEIT: Extreme-Ultraviolet Imaging Telescope for the SOHO Mission
Delaboudinière, J.-P.; Artzner, G. E.; Brunaud, J. et al

in Solar Physics (1995), 162

The Extreme-ultraviolet Imaging Telescope (EIT) will provide wide-field images of the corona and transition region on the solar disc and up to 1.5 Ro above the solar limb. Its normal incidence multilayer ... [more ▼]

The Extreme-ultraviolet Imaging Telescope (EIT) will provide wide-field images of the corona and transition region on the solar disc and up to 1.5 Ro above the solar limb. Its normal incidence multilayer-coated optics will select spectral emission lines from Fe IX (171 Å), Fe XII (195 Å), Fe XV (284 Å), and He II (304 Å) to provide sensitive temperature diagnostics in the range from 6 × 10[SUP]4[/SUP] K to 3 × 10[SUP]6[/SUP] K. The telescope has a 45 x 45 arcmin field of view and 2.6 arcsec pixels which will provide approximately 5-arcsec spatial resolution. The EIT will probe the coronal plasma on a global scale, as well as the underlying cooler and turbulent atmosphere, providing the basis for comparative analyses with observations from both the ground and other SOHO instruments. This paper presents details of the EIT instrumentation, its performance and operating modes. [less ▲]

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