Far Ultraviolet Imaging from the Image Spacecraft. 3. Spectral Imaging of Lyman-∝ and OI 135.6 nm



Two FUV Spectral imaging instruments, the Spectrographic Imager (SI) and the Geocorona Photometer (GEO) provide IMAGE with simultaneous global maps of the hydrogen (121.8 nm) and oxygen 135.6 nm components of the terrestrial aurora and with observations of the three dimensional distribution of neutral hydrogen in the magnetosphere (121.6 nm). The SI is a novel instrument type, in which spectral separation and imaging functions are independent of each other. In this instrument, two-dimensional images are produced on two detectors, and the images are spectrally filtered by a spectrograph part of the instrument. One of the two detectors images the Dopplershifted Lyman-α while rejecting the geocoronal ‘cold’ Ly-α, and another detector images the OI 135.6 nm emission. The spectrograph is an all-reflective Wadsworth configuration in which a grill arrangement is used to block most of the cold, un-Doppler-shifted geocoronal emission at 121.567 nm. The SI calibration established that the upper limit of transmission at cold geocoronal Ly-α is less than 2%. The measured light collecting efficiency was 0.01 and 0.008 cm2 at 121.8 and at 135.6 nm, respectively. This is consistent with the size of the input aperture, the optical transmission, and the photocathode efficiency. The expected sensitivity is 1.8 x 10-2 and 1.3 x 10-2 counts per Rayleigh per pixel for each 5 s viewing exposure per satellite revolution (120 s). The measured spatial resolution is better than the 128 x 128 pixel matrix over the 15° x 15° field of view in both wavelength channels. The SI detectors are photon counting devices using the cross delay line principle. In each detector a triple stack microchannel plate (MCP) amplifies the photo-electronic charge which is then deposited on a specially configured anode array. The position of the photon event is measured by digitizing the time delay between the pulses detected at each end of the anode structures. This scheme is intrinsically faster than systems that use charge division and it has a further advantage that it saturates more gradually at high count rates. The geocoronal Ly-α is measured by a three-channel photometer system (GEO) which is a separate instrument. Each photometer has a built in MgF2 lens to restrict the field of view to one degree and a ceramic electron multiplier with a KBr photocathode. One of the tubes is pointing radially outward perpendicular to the axis of satellite rotation. The optic of the other two subtend 60° with the rotation axis. These instruments take data continuously at 3 samples per second and rely on the combination of satellite rotation and orbital motion to scan the hydrogen cloud surrounding the earth. The detective efficiencies (effective quantum efficiency including windows) of the three tubes at Ly-α are between 6 and 10%.


Entrance Slit Exit Slit Intermediate Image Pulse Height Distribution Parallel Light 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Ajello, J. M: 1990, ‘Solar Minimum Ly-α Sky Background Observations from Pioneer Venus Orbiter Ultraviolet Spectrometer: Solar Wind Latitude Variation’, J. Geophys. Res. 95, 14855–14861.ADSCrossRefGoogle Scholar
  2. Anderson, D. E. and Hord, C. W.: 1977, ‘Multidimensional Radiative Transfer — Applications to Planetary Coronae’, Planetary Space Sci. 25, 563–571.ADSCrossRefGoogle Scholar
  3. Anger, C. D., Murphree, J. S., Vallance-Jones, A., King, R. A., Broadfoot, A. L., Cogger, L. L., Creutzberg, F., Gattinger, R. L., Gustafsson, G., Harris, F. R., Haslett, J. W., Llewellyn, E. J., McConnell, J. C., McEwen, D. J., Richardson, E. H., Rostoker, G., Sandel, B. R., Shepherd, G. G., Venkatesan, D., Wallis, D. D. and Witt, G.: 1987, ‘Scientific Results from the Viking Ultraviolet Imager: An Introduction’, Geophys. Res. Lett. 14, 383–386.ADSCrossRefGoogle Scholar
  4. Basu, B., Jasperse, J. R., Strickland, D. J. and Daniell, R. E.: 1993, ‘Transport-Theoretic Model for the Electron-Proton-Hydrogen Atom Aurora’, J. Geophys. Res. 98, 21, 517–521, 532.Google Scholar
  5. Bishop, J.: 1999, ‘Transport of Resonant Atomic Hydrogen Emissions in the Thermosphère and Geocorona: Model Description and Applications’, J. Quant. Spectr. Rad. Transfer 61, 473–491.ADSCrossRefGoogle Scholar
  6. Bush, B. and Chakrabarti, S.: 1995, ‘Analysis of Ly-α and He I 584-Å Airglow Measurements Using a Spherical Radiative Transfer Model’, J. Geophys. Res. 100, 19609–19625.ADSCrossRefGoogle Scholar
  7. Chamberlain, J. W.: 1963, ‘Planetary Coronae and Atmospheric Evaportaion’, Planetary Space Sci. 11, 901–960.ADSCrossRefGoogle Scholar
  8. Eather R. H.: 1967, ‘Auroral Proton Precipitation and Hydrogen Emissions’, Rev. Geophys. Space Phys. 5, 207–285.ADSCrossRefGoogle Scholar
  9. Edgar, B. C., Miles, W. T. and Green, A. E. S.: 1973, ‘Energy Deposition of Protons in Molecular Nitrogen and Application to Proton Auroral Phenomena’, J. Geophys. Res. 78, 6595–6606.ADSCrossRefGoogle Scholar
  10. Frank, L. A. and Craven, J. D.: 1988, ‘Imaging Results from Dynamics Explorer 1’, Rev. Geophys. 26, 249–283.ADSCrossRefGoogle Scholar
  11. Galand, M. and Richmond, A. D.: 1999, ‘Magnetic Mirroring in an Incident Proton Beam’, J. Geophys. Res. 104, 4447–4455.ADSCrossRefGoogle Scholar
  12. Ishimoto, M., Meng, C. I., Romick, G. R. and Huffman, R. E.: 1989, ‘Anomalous UV Auroral Spectra During a Large Magnetic Disturbance’, J. Geophys. Res. 94, 6955–6960.ADSCrossRefGoogle Scholar
  13. Jasperse, J. R. and Basu, B.: 1982, ‘Transport Theoretical Solutions for Auroral Proton and H Atom Fluxes and Related Quantities’, J. Geophys. Res. 87, 811–822.ADSCrossRefGoogle Scholar
  14. Jelinsky, S. R., Siegmund, O. H. W. and Mir, J. A.: 1996, ‘Progress in Soft X-Ray and UV Photocathodes’, Proc. SPIE 2808, 617–625.ADSCrossRefGoogle Scholar
  15. Lampton, M. O., Siegmund and Raffanti, R.: 1987, ‘Delay Line Anodes for MicroChannel Plate Spectrometers’, Rev. Sci. Instrum, 58, 2298–2305.ADSCrossRefGoogle Scholar
  16. Lampton, M.: 1998, ‘A Timing Discriminator for Space Flight Applications’, Rev. Sci. Instrum. 69, 3062–3065.ADSCrossRefGoogle Scholar
  17. Lemaitre, M.-P., Laurent, J., Besson, J., Girard, A., Lippens, C., Muller, C., Vercheval, J. and Ackerman, M.: 1984, ‘Sample Performance of the Grille Spectrometer’, Science 225, 171–172.ADSCrossRefGoogle Scholar
  18. Loewen, E. G. and Popov, E.: 1997, Diffraction Gratings and Applications, Marcel Dekker, Inc., New York, p. 175ff.Google Scholar
  19. Marov, M. Y, Shematovich, V. L, Bisikalo, D. V. and Gerard, J. C.: 1997, Nonequilibrium Processes in the Planetary and Cometary Atmospheres: Theory and Applications, Kluwer Academic Publishers, Dordrecht.CrossRefGoogle Scholar
  20. Meier, R. R.: 1991, ‘Ultraviolet Spectroscopy and Remote Sensing of the Upper Atmosphere’, Space Sci. Rev. 58, 1–185.ADSCrossRefGoogle Scholar
  21. Pryor, W. R., Witte, M. and Ajello, J. M.: 1998, ‘Interplanetary Ly-α Remote Sensing with the Ulysses Interstellar Neutral Gas Experiment’, J. Geophys. Res. 103, 26813–26831.ADSCrossRefGoogle Scholar
  22. Rairden, R. L., Frank, L. A. and Craven, J. D.: 1986, ‘Geocoronal Imaging with Dynamics Explorer’, J. Geophys. Res. 91, 13613–13630.ADSCrossRefGoogle Scholar
  23. Siegmund, O. H. W. and Stock, J.: 1991, ‘Performance of Low Resistance MicroChannel Plate Stacks’, Proc. SPIE 1549, 81–89.ADSCrossRefGoogle Scholar
  24. Siegmund, O. H. W., et al.: 1994, ‘Delay Line Detectors for the UVCS and SUMER Instruments on the SOHO Satellite’, Proc. SPIE 2280 89–100.ADSCrossRefGoogle Scholar
  25. Stock, J. M., Siegmund, O. H. W., Hull, J. S., Kromer, K. E., Jelinsky, S. R., Heetderks, H. D., Lampton, M. L. and Mende, S. B.: 1998, ‘Cross Delay Line MicroChannel Plate Detectors for the Spectrographic Imager on the IMAGE Satellite’, Proc. SPIE 3445, 407–414.ADSCrossRefGoogle Scholar
  26. Strickland, D. J. and Anderson, D. E., Jr.: 1983, ‘Radiation Transport Effects on the OI 1356-AA Limb Intensity Profile in the Dayglow’, J. Geophys. Res. 88, 9260–9264.ADSCrossRefGoogle Scholar
  27. Strickland, D. J., Jasperse, J. R. and Whalen, J. A.: 1983, ‘Dependence of Auroral FUV Emissions on the Incident Electron Spectrum and Neutral Atmosphere’, J. Geophys. Res. 88, 8051–8062.ADSCrossRefGoogle Scholar
  28. Strickland, D. J., Danielle, R. E., Jr., Jasperse, J. R. and Basu, B.: 1993, ‘Transport-Theoretic Model for the Electron-Proton-Hydrogen Atom Aurora: 2. Model Results’, J. Geophys. Res. 98, 21533–21548.ADSCrossRefGoogle Scholar
  29. Torr, M. R., Torr, D. G., Zukic, M., Johnson, R. B., Ajello, J., Banks, P., Clark, K., Cole, K., Keffer, C., Parks, G., Tsurantani, B. and Spann, J.: 1995, ‘A Far Ultraviolet Imager for the International Solar-Terrestrial Physics Mission’, Space Sci. Rev. 71, 329.ADSCrossRefGoogle Scholar
  30. Williams, D. J.: 1987, ‘Ring Current and Radiation Belts’, Rev. Geophys. 25, 570–578.ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2000

Authors and Affiliations

  1. 1.Space Sciences LaboratoryUniversity of California BerkeleyBerkeleyUSA
  2. 2.Centre Spatiale de LiègeLiègeBelgium
  3. 3.University of LiègeLiègeBelgium
  4. 4.Lockheed-Martin Palo Alto Research LaboratoriesPalo AltoUSA
  5. 5.Max Planck Institut fur AeronomieKatlenburg-LindauGermany

Personalised recommendations