The Freja Ultraviolet Imager

Murphree, J. S.; King, Robert A.; Payne, Tamara; Smith, K. A.; Reid, David; Adema, J.; Gordon, B.; Wlochowicz, R.

doi:10.1007/978-94-011-0299-5_2

Cited by 10 publications

(9 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previously flown satellite imaging experiments have demonstrated the suitability of the vacuum ultraviolet spectral region for remote sensing observation of auroral precipitation (Frank et al, 1981;Anger et al, 1987;Frank and Craven, 1988;Murphree et al, 1994). In the wavelength region 120-190 nm, a downwardviewing imager is minimally contaminated by scattered sun light from clouds and the ground and the radiance of the aurora observed in a nadir viewing geometry can be distinguished from the high latitude dayglow.…”

Section: Introductionmentioning

confidence: 99%

Summary of quantitative interpretation of IMAGE far ultraviolet auroral data

Frey

Mende

Immel

et al. 2003

Space Science Reviews

View full text Add to dashboard Cite

Direct imaging of the magnetosphere by instruments on the IMAGE spacecraft is supplemented by simultaneous observations of the global aurora in three far ultraviolet (FUV) wavelength bands. The purpose of the multi-wavelength imaging is to study the global auroral particle and energy input from the magnetosphere into the atmosphere. This paper describes the method for quantitative interpretation of FUV measurements. The Wide-Band Imaging Camera (WIC) provides broad band ultraviolet images of the aurora with maximum spatial resolution by imaging the nitrogen lines and bands between 140 and 180 nm wavelength. The Spectrographic Imager (SI), a dual wavelength monochromatic instrument, images both Doppler-shifted Lyman-α emissions produced by precipitating protons, in the SI-12 channel and OI 135.6 nm emissions in the SI-13 channel. From the SI-12 Doppler shifted Lyman-α images it is possible to obtain the precipitating proton flux provided assumptions are made regarding the mean energy of the protons. Knowledge of the proton (flux and energy) component allows the calculation of the contribution produced by protons in the WIC and SI-13 instruments. Comparison of the corrected WIC and SI-13 signals provides a measure of the electron mean energy, which can then be used to determine the electron energy flux. To accomplish this, reliable emission modeling and instrument calibrations are required. In-flight calibration using early-type stars was used to validate the pre-flight laboratory calibrations and determine long-term trends in sensitivity. In general, very reasonable agreement is found between in-situ measurements and remote quantitative determinations.

show abstract

Section: Introductionmentioning

confidence: 99%

Summary of quantitative interpretation of IMAGE far ultraviolet auroral data

Frey

Mende

Immel

et al. 2003

Space Science Reviews

View full text Add to dashboard Cite

show abstract

“…Its temporal resolution was 20 s, one image per satellite spin, and the exposure time 1 s. With Viking the development of the global aurora could be followed with higher temporal resolution than ever before. The imagers on Freja (Murphree et al, 1994) had much better spatial and temporal resolution than Viking, but, due to the much lower altitude of the orbit, Freja did not give the global overview. Freja had apogee at 1800 km and Viking at 14,000 km.…”

Section: Instruments On Satellitesmentioning

confidence: 97%

Fine structure of optical aurora

Sandahl

Sergienko

Brändström

2008

Journal of Atmospheric and Solar-Terrestrial Physics

View full text Add to dashboard Cite

“…Table 2 summarizes this comparison to the Polar Ultraviolet Imager (UVI) instrument LBH long and 1356 filters 14 , the Spectrographic Imager 1356 channel (SI13 16 ) and Wideband Imaging Camera (WIC 15 ) both on the IMAGE mission. For reference, the WIC has the same mirror design as those used on the Viking 18 , Freja 19 , and Interball 20 missions. Also, the Polar VIS Earth Camera 8 is of similar optical design as the Polar UVI without a filter wheel in that both use off-axis three mirror imaging optics.…”

Section: Comparison With Existing Designsmentioning

confidence: 99%

Compact FUV camera concept for space weather applications

Spann

2005

Solar Physics and Space Weather Instrumentation

View full text Add to dashboard Cite

Far ultraviolet (FUV) images of Earth from space have proven invaluable in revealing contextual phenomena associated with space weather in the high latitude auroral regions and in the mid and equatorial regions. Images of this nature can be used to investigate compelling questions associated with the interaction of the ionosphere/mesospheremagnetosphere-solar wind.Observations using images that lead to quantitative analyses are required to significantly advance the state of knowledge with regard to the affects of space weather and the interaction between and within these regions of Geospace. Current available image data sets are sufficient for qualitative analysis and morphological investigations, and while quantitative analyses are possible, they are difficult and limited to few events at best 1,2 . In order to qualitatively access the time, spatial, and causal phenomena on global scales, simultaneous images of various FUV emissions with a combination of better spatial, temporal and spectral resolution and sensitivity than currently available are required.We present an instrument concept that is being developed to improve the spatial, temporal and spectral resolution and sensitivity needed to perform the quantitative analysis that enable significant advancement in our understanding of the impact of space weather on Geospace. The approach is to use the "self-filtering" concept 3 that combines the imaging and filtering functions and thus reduces the size of the 4-mirror off-axis optical system. The optical and filter design will de described. IntroductionThis paper describes a camera design, referred to as "compact camera" that in principle improves the spatial, temporal, and spectral resolution and sensitivity needed to perform quantitative analysis of earth observations in the far ultraviolet. These observations are required in order to enable significant advancement in our understanding of the impact of space weather on Geospace.Far ultraviolet (FUV) images of Earth from space have proven invaluable in revealing contextual phenomena in the high latitude auroral regions and in the mid and equatorial regions. Images of this nature can be used to investigate compelling questions associated with the interaction of the ionosphere/mesosphere-magnetosphere-solar wind. To significantly advance the state of knowledge with regard to the interaction between and within these regions of geospace, observations that lead to quantitative analyses are required. Current available image data sets are sufficient for qualitative analysis and morphological investigations, and while quantitative analyses are possible, they are difficult and limited to few events at best 1,2 . In order to qualitatively access the time, spatial, and causal phenomena on global scales, simultaneous images of various FUV emissions with a combination of better spatial, temporal and spectral resolution and sensitivity than currently available are required.The coupling between the Magnetosphere and Ionosphere, as reflected in the fluctuating acceleration pot...

show abstract

The Freja Ultraviolet Imager

Cited by 10 publications

References 20 publications

Summary of quantitative interpretation of IMAGE far ultraviolet auroral data

Summary of quantitative interpretation of IMAGE far ultraviolet auroral data

Fine structure of optical aurora

Compact FUV camera concept for space weather applications

Contact Info

Product

Resources

About