Neutral hydrogen density profiles derived from geocoronal imaging Ostgaard, N., Mende, S.B., Frey, H.U., Gladstone, R. The geocorona is produced when solar Lyman alpha radiation is resonance scattered by neutral hydrogen in the exosphere. Measurements of the geocoronal brightness from space can therefore be used to derive the density profile of neutral hydrogen sorrounding the Earth. The Geocorononal Imager (GEO) which is part of the FUV imaging system onboard the IMAGE satellite, is designed to measure the geocoronal Lyman alpha emissions. In this paper we present radial density profiles of the neutral hydrogen in the magnetosphere derived from the GEO data of Lyman alpha column brightness. The variable solar Lyman alpha flux is obtained from the UARS/SOLSTICE measurements and the scattered solar Lyman alpha emissions from interplanetary hydrogen is obtained from a model. At high altitudes (>3 RE) we assume that the exosphere can be considered as an optical thin medium. Assuming that the hydrogen density profile can be expressed as a double exponential it is shown that the Lyman $\alpha$ column brightness can be converted to hydrogen density profiles in each local time sector. Our results show the same shape but indicate higher hydrogen density >5 RE than has been reported earlier. Our results are valid >3 RE. _______________ Presented at the 2002 Spring A.G.U. Meeting, Washington, D.C., U.S.A., 28-31 May 2002