Untitled

Judge, D. L.; McMullin, D.; Ogawa, Hiromitsu; Hovestadt, D.; Klecker, B.; Hilchenbach, M.; Möbius, E.; Canfield, L. R.; Vest, Robert E.; Watts, R. N.; Tarrio, Charles S.; Kühne, M.; Würz, Peter

doi:10.1023/a:1004929011427

“…The ESP is a transmission grating and photodiode instrument similar to the SOHO/SEM (Judge et al, 1998). ESP has four channels centered on 18.2, 25.7, 30.4, and 36.6 nm that are each approximately 4 nm in spectral width.…”

Section: Eve Instrumentationmentioning

confidence: 99%

Extreme Ultraviolet Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Overview of Science Objectives, Instrument Design, Data Products, and Model Developments

Woods

¹

,

Eparvier

²

,

Hock

³

et al. 2010

View full text Add to dashboard Cite

The highly variable solar extreme ultraviolet (EUV) radiation is the major energy input to the Earth's upper atmosphere, strongly impacting the geospace environment, affecting satellite operations, communications, and navigation. The Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO) will measure the solar EUV irradiance from 0.1 to 105 nm with unprecedented spectral resolution (0.1 nm), temporal cadence (ten seconds), and accuracy (20%). EVE includes several irradiance instruments: The Multiple EUV Grating Spectrographs (MEGS)-A is a grazingincidence spectrograph that measures the solar EUV irradiance in the 5 to 37 nm range with 0.1-nm resolution, and the MEGS-B is a normal-incidence, dual-pass spectrograph that measures the solar EUV irradiance in the 35 to 105 nm range with 0.1-nm resolution. To provide MEGS in-flight calibration, the EUV SpectroPhotometer (ESP) measures the solar EUV irradiance in broadbands between 0.1 and 39 nm, and a MEGS-Photometer measures the Sun's bright hydrogen emission at 121.6 nm. The EVE data products include a near real-time space-weather product (Level 0C), which provides the solar EUV irradiance in specific bands and also spectra in 0.1-nm intervals with a cadence of one minute and with a time delay of less than 15 minutes. The EVE higher-level products are Level 2 with the solar EUV irradiance at higher time cadence (0.25 seconds for photometers and ten seconds for spectrographs) and Level 3 with averages of the solar irradiance over a day and over each one-hour period. The EVE team also plans to advance existing models of solar EUV irradiance and to operationally use the EVE measurements in models of Earth's ionosphere and thermosphere. Improved understanding of the evolution of solar flares and extending the various models to incorporate solar flare events are high priorities for the EVE team.

show abstract

“…Almost 15 years later the characteristics of the helium cone could again be studied more thoroughly and systematically using a sensitive time-of-flight spectrometer on the ACE spacecraft in near Earth orbit at L1 , and the Nozomi space probe to Mars (Yamamoto & Tsuruda 1998). Furthermore, simultaneous observations of the UV ionization rate of He are now available from the Solar EUV Monitor (SEM) in the CELIAS instrument package on SOHO Judge et al 1997). Here we report in some detail on results of these investigations, concentrating on ACE and Ulysses measurements of pickup helium, the most comprehensive pickup He data set to date.…”

Section: Introductionmentioning

confidence: 99%

Observations of the helium focusing cone with pickup ions

Gloeckler

¹

,

Möbius

²

,

Geiss

³

et al. 2004

A&A

Self Cite

View full text Add to dashboard Cite

Abstract. The helium gravitational focusing cone has been observed using pickup He + , first during the solar minimum in [1984][1985] with the AMPTE/IRM spacecraft, and again in more detail from 1998 to 2002 with ACE and in 2000 with Nozomi. Five traversals of the cone allow us to obtain an accurate determination of the ecliptic longitude of the interstellar wind flow direction, λ = 74.43 • ± 0.33 • , while observations of pickup He ++ with Ulysses give us an estimate, relatively free of instrumental systematic uncertainties, of the neutral He density, n He = 0.0151 ± 0.0015 cm −3 , in the Local Interstellar Cloud. From best fits to the measured velocity distributions of pickup He + using time-stationary models we deduce the radial dependence and magnitude of electron-impact ionization rates that cannot presently be measured, and find this to be an important ionization process in the inner ( < ∼ 0.5 AU) heliosphere. We obtain excellent model fits to the 1998 cone profile using measured or deduced rates and known interstellar He parameters, and from this conclude that cross-field diffusion of pickup He + is small. Furthermore, we find no evidence for extra sources of He in or near the cone region. Best fits to the velocity distributions of He + are obtained assuming isotropic solar-wind-frame distributions, and we conclude from this that the scattering mean free path for pickup He + in the turbulent slow solar wind is small, probably less than 0.1 AU. We argue that application of 3D, time-dependent models for computation of the spatial distribution of interstellar neutral helium in the inner heliosphere may lead to excellent fits of short-term averaged pickup He + data without assuming loss rates that are significantly different from production rates.

show abstract

“…Observations of the solar EUV irradiance with higher temporal cadence, as needed to study flares, are severely limited. The SOHO Solar EUV Monitor (SEM, Judge et al, 1998) and GOES/XRS (Garcia, 1994) measurements do provide high time cadence but only in a few broad wavelength bands. EVE's spectrally-resolved observations with a temporal cadence of ten seconds will greatly advance the specification and understanding of the spectral variations during flare events throughout the XUV and EUV spectrum.…”

Section: Eve Objective 1 -Specify Solar Euv Irradiancementioning

confidence: 99%

“…The ESP instrument is a non-focusing, broadband spectrograph with a transmission grating and IRD silicon photodiodes similar to the SOHO/SEM instrument (Judge et al, 1998). In front of the entrance slit is an Al (150 nm) foil filter made by Luxel Corp. to limit the out-of-band light that enters the instrument.…”

Section: Esp Instrumentmentioning

confidence: 99%

“…The extracted emission lines are total irradiances over the lines including the background. There are several broadbands including EVE's photometer measurements and several wavelength bands extracted from the MEGS spectra that simulate bands from other instruments, such as AIA, SOHO/Solar EUV Monitor (SEM) (Judge et al, 1998), and GOES/EUV Sensor (EUVS) (Viereck et al, 2007). For these other instrument bands, their normalized responsivity profiles are convolved with the MEGS spectrum so that the EVE equivalent bands can be more directly compared for calibration and validation purposes.…”

Section: Eve Levelmentioning

confidence: 99%

See 1 more Smart Citation

Extreme Ultraviolet Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Overview of Science Objectives, Instrument Design, Data Products, and Model Developments

Woods

¹

,

Eparvier

²

,

Hock

³

et al. 2010

The Solar Dynamics Observatory

View full text Add to dashboard Cite

The highly variable solar extreme ultraviolet (EUV) radiation is the major energy input to the Earth's upper atmosphere, strongly impacting the geospace environment, affecting satellite operations, communications, and navigation. The Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO) will measure the solar EUV irradiance from 0.1 to 105 nm with unprecedented spectral resolution (0.1 nm), temporal cadence (ten seconds), and accuracy (20%). EVE includes several irradiance instruments: The Multiple EUV Grating Spectrographs (MEGS)-A is a grazingincidence spectrograph that measures the solar EUV irradiance in the 5 to 37 nm range with 0.1-nm resolution, and the MEGS-B is a normal-incidence, dual-pass spectrograph that measures the solar EUV irradiance in the 35 to 105 nm range with 0.1-nm resolution. To provide MEGS in-flight calibration, the EUV SpectroPhotometer (ESP) measures the solar EUV irradiance in broadbands between 0.1 and 39 nm, and a MEGS-Photometer measures the Sun's bright hydrogen emission at 121.6 nm. The EVE data products include a near real-time space-weather product (Level 0C), which provides the solar EUV irradiance in specific bands and also spectra in 0.1-nm intervals with a cadence of one minute and with a time delay of less than 15 minutes. The EVE higher-level products are Level 2 with the solar EUV irradiance at higher time cadence (0.25 seconds for photometers and ten seconds for spectrographs) and Level 3 with averages of the solar irradiance over a day and over each one-hour period. The EVE team also plans to advance existing models of solar EUV irradiance and to operationally use the EVE measurements in models of Earth's ionosphere and thermosphere. Improved understanding of the evolution of solar flares and extending the various models to incorporate solar flare events are high priorities for the EVE team.

show abstract

Untitled

Cited by 184 publications

References 0 publications

Extreme Ultraviolet Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Overview of Science Objectives, Instrument Design, Data Products, and Model Developments

Extreme Ultraviolet Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Overview of Science Objectives, Instrument Design, Data Products, and Model Developments

Observations of the helium focusing cone with pickup ions

Extreme Ultraviolet Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Overview of Science Objectives, Instrument Design, Data Products, and Model Developments

Contact Info

Product

Resources

About