Initial ion equatorial pitch angle distributions from medium and high energy 
neutral atom images obtained by IMAGE

J.D. Perez, G. Kozlowski, P. C:son-Brandt, D.G. Mitchell, J.-M. Jahn, 
C.J. Pollock, and X.X. Zhang


Examples of the extraction of equatorial ion pitch angle distributions from
energetic neutal atom images taken by the HENA instrument on June 10, 2000
between 1200 and 1600 UT and MENA on August 12, 2000 at about 1000 UT on board
the IMAGE satellite are presented. The extraction is performed using a method of
deconvolution that expands the unknown equatorial ion pitch angle distribution
in terms of tri-cubic splines, and then finds the expansion coefficients by
requiring that the result fit the data and be as smooth as possible.

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Geophysical Research Letters, Vol. 28, No. 6 , pp. 1155-1158, March, 2001