[Heber 1996 b]

Spatial variation of > 106 MeV proton fluxes observed during the Ulysses rapid latitude scan: Ulysses COSPIN/KET results

B. Heber, W. Dröge, P. Ferrando, H. Kunow, R. Müller-Mellin, C. Paizis, A. Raviart and G. Wibberenz.
Spatial variation of > MeV proton fluxes observed during the Ulysses rapid latitude scan: Ulysses COSPIN/KET results. Geophysical Research Letters 23 (12), 1513-1516.


Contents

The authors present measurements of galactic proton fluxes with energies above 106 MeV made by the Kiel Electron Telescope on board the Ulysses spacecraft during the fast scan form the south polar passage in September 1994 to the north pole in August 1995, under solar minimum conditions. To compare the fluxes the authors used data from the HET instrument of the University of Chicago on IMP-8. Comparison of proton fluxes at high latitudes and in the ecliptic shows a 20% higher flux in polar regions. The flux increase is not symmetric with respect to the heliographic equator but rather with respect to a surface shifted by 7° south. In such a coordinate system the latitudinal gradient in both hemispheres has a value of (0.33 ± 0.02)%/deg in the area 30° to 55° S and 20° to 60° N. For latitudes greater than 60° the gradient decreases. Also the radial variation is small compared to the latitudinal variation.


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