Remote sensing of H from Ulysses and Galileo

We model interplanetary H Lyman-alpha (L alpha) observations from Galileo U VS (Ultraviolet Spectrometer) and EUVS (Extreme Ultraviolet Spectrometer) ( Hord et al., 1992) and the Ulysses interstellar neutral gas (GAS) instrumen t (Witte et al., 1992). EUVS measurements near solar maximum (max) in 1990- 1992 have a peaked brightness maximum upwind due to a rather isotropic sola r wind charge-exchange ionization pattern (A=0-0.25). GAS measurements from solar minimum (min) in 1997 have a plateau in the upwind direction that we model using Ulysses SWOOPS (solar wind plasma experiment) solar min data o n solar wind density and velocity at different heliographic latitudes. The isotropic ionization pattern deduced from EUVS at solar max may be consiste nt with recent SWOOPS results (McComas et al., 2000b, c) that high speed so lar wind is absent at high latitudes during solar max. Galileo and Ulysses L alpha data favor higher H temperatures (15 000-18 000 K) than previous mo dels.