SDO-EVE EUV spectrograph optical design and performance

Crotser, David A.; Woods, Thomas N.; Eparvier, F. G.; Triplett, Matthew; Woodraska, D.

doi:10.1117/12.732592

Cited by 18 publications

(21 citation statements)

References 3 publications

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“…This is done by first rebinning the non-constant RH data (between 30 and 130 nm) to a constant wavelength spacing of 0.005 nm, before convolving the RADYN and RH profiles with the instrumental profile of EVE, given by a Gaussian of FWHM 0.085 nm (see Crotser et al 2007), and then resampling the data to replicate EVEʼs wavelength bin size of 0.02 nm. Measurements of the line centroid variations are performed by both Gaussian fitting and intensity-weighted means.…”

Section: Description Of Simulations and Methodsmentioning

confidence: 99%

Modeling of the Hydrogen Lyman Lines in Solar Flares

Brown

Fletcher

Kerr

et al. 2018

ApJ

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The hydrogen Lyman lines (91.2 nm < λ<121.6 nm) are significant contributors to the radiative losses of the solar chromosphere, and they are enhanced during flares. We have shown previously that the Lyman lines observed by the Extreme Ultraviolet Variability instrument onboard the Solar Dynamics Observatory exhibit Doppler motions equivalent to speeds on the order of 30 km s −1 . However, contrary to expectations, both redshifts and blueshifts were present and no dominant flow direction was observed. To understand the formation of the Lyman lines, particularly their Doppler motions, we have used the radiative hydrodynamic code, RADYN, along with the radiative transfer code, RH, to simulate the evolution of the flaring chromosphere and the response of the Lyman lines during solar flares. We find that upflows in the simulated atmospheres lead to blueshifts in the line cores, which exhibit central reversals. We then model the effects of the instrument on the profiles, using the Extreme Ultraviolet Variability Experiment (EVE) instrumentʼs properties. What may be interpreted as downflows (redshifted emission) in the lines, after they have been convolved with the instrumental line profile, may not necessarily correspond to actual downflows. Dynamic features in the atmosphere can introduce complex features in the line profiles that will not be detected by instruments with the spectral resolution of EVE, but which leave more of a signature at the resolution of the Spectral Investigation of the Coronal Environment instrument onboard the Solar Orbiter.

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Section: Description Of Simulations and Methodsmentioning

confidence: 99%

Modeling of the Hydrogen Lyman Lines in Solar Flares

Brown

Fletcher

Kerr

et al. 2018

ApJ

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“…Westhoff et al (2007) provide more information about the CCDs used with MEGS. Ray-tracing results for the MEGS spectrometers are found in Crotser et al (2004Crotser et al ( , 2007. The MEGS CCDs are twodimensional arrays.…”

Section: Eve Instrumentsmentioning

confidence: 99%

“…These fits of the wavelength scale are verified by ray tracing the optical system (e.g. see Crotser et al 2004Crotser et al , 2007.…”

Section: Wavelength Scalementioning

confidence: 99%

Extreme Ultraviolet Variability Experiment (EVE) Multiple EUV Grating Spectrographs (MEGS): Radiometric Calibrations and Results

Hock

Chamberlin

Woods

et al. 2010

The Solar Dynamics Observatory

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The NASA Solar Dynamics Observatory (SDO), scheduled for launch in early 2010, incorporates a suite of instruments including the Extreme Ultraviolet Variability Experiment (EVE). EVE has multiple instruments including the Multiple Extreme ultraviolet Grating Spectrographs (MEGS) A, B, and P instruments, the Solar Aspect Monitor (SAM), and the Extreme ultraviolet SpectroPhotometer (ESP). The radiometric calibration of EVE, necessary to convert the instrument counts to physical units, was performed at the National Institute of Standards and Technology (NIST) Synchrotron Ultraviolet Radiation Facility (SURF III) located in Gaithersburg, Maryland. This paper presents the results and derived accuracy of this radiometric calibration for the MEGS A, B, P, and SAM instruments, while the calibration of the ESP instrument is addressed by Didkovsky et al. (Solar Phys., 2010, doi:10.1007. In addition, solar measurements that were taken on 14 April 2008, during the NASA 36.240 sounding-rocket flight, are shown for the prototype EVE instruments.

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“…Annual sounding rocket underflights of similar instruments will track longer-term changes in the sensitivity of the EVE instruments. Eparvier et al (2004), Crotser et al (2004Crotser et al ( , 2007, , and Hock et al (2010) provide more details about LASP's MEGS and its calibration results.…”

Section: Eve Instrumentationmentioning

confidence: 99%

“…The wavelength coverage of all instruments is shown in Figure 3, along with the solar-cycle minimum spectrum obtained with the prototype EVE onboard a sounding rocket flight on 14 April 2008 (Chamberlin et al, 2009). Eparvier et al (2004), Crotser et al (2004Crotser et al ( , 2007, , Didkovsky et al (2007Didkovsky et al ( , 2010, and Hock et al (2010) provide details of the optical designs for the EVE instruments, but a brief overview of the instruments is included here.…”

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

et al. 2010

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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.

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SDO-EVE EUV spectrograph optical design and performance

Cited by 18 publications

References 3 publications

Modeling of the Hydrogen Lyman Lines in Solar Flares

Modeling of the Hydrogen Lyman Lines in Solar Flares

Extreme Ultraviolet Variability Experiment (EVE) Multiple EUV Grating Spectrographs (MEGS): Radiometric Calibrations and Results

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

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