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Geocoronal imaging with Dynamics ExplorerThe ultraviolet photometer of the University of Iowa spin-scan auroral imaging instrumentation on board Dynamics Explorer-1 has returned numerous hydrogen Lyman alpha images of the geocorona from altitudes of 570 km to 23,300 km (1.09 R sub E to 4.66 R sub E geocentric radial distance). The hydrogen density gradient is shown by a plot of the zenith intensities throughout this range, which decrease to near celestial background values as the spacecraft approaches apogee. Characterizing the upper geocorona as optically thin (single-scattering), the zenith intensity is converted directly to vertical column density. This approximation loses its validity deeper in the geocorona, where the hydrogen is demonstrated to be optically thick in that there is no Lyman alpha limb brightening. Further study of the geocoronal hydrogen distribution will require computer modeling of the radiative transfer.
Document ID
19870039729
Document Type
Reprint (Version printed in journal)
Authors
Rairden, R. L. (Iowa Univ. Iowa City, IA, United States)
Frank, L. A. (Iowa Univ. Iowa City, IA, United States)
Craven, J. D. (Iowa, University Iowa City, United States)
Date Acquired
August 13, 2013
Publication Date
December 1, 1986
Publication Information
Publication: Journal of Geophysical Research
Volume: 91
ISSN: 0148-0227
Subject Category
GEOPHYSICS
Funding Number(s)
CONTRACT_GRANT: N00014-85-K-0404
CONTRACT_GRANT: N00014-76-C-0016
CONTRACT_GRANT: NGL-16-001-002
CONTRACT_GRANT: NAG5-483
CONTRACT_GRANT: NAS5-24293
CONTRACT_GRANT: NAS5-25689
Distribution Limits
Public
Copyright
Other