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Session 49 - First Results from the Solar and Heliospheric Observatory (SOHO).
Oral session, Tuesday, June 11
The SWAN instrument is a Lyman alpha photometer/imager, which can determine the intensity of UV radiation in the band 110-180 nm in the whole sky with a resolution of 1° and high SNR. Observations of many stars allow an absolute calibraton. In January 96 the first all-sky UV map was obtained. The L alpha emission of the extended geocorona was mapped, as well as the hydrogen cloud around several comets including Hyakutake 1996 B2 . At closest approach from Earth the cometary H enveloppe extended over more than 50° and the evolution was monitored through perihelion.The large scale latitude distribution of the solar wind can be determined from the full Lyman alpha sky map, because it carves a cavity inside the flow of interstellar H through the solar system. Some anisotropy of the solar wind flow are clearly detected, with more solar wind near the solar equatorial plane, as evidenced from the groove present in the sky map near the upwind direction. One pixel is covered with BaF2, excluding radiation below 140 n m, allowing to establish also a full sky map in the range 140-180 nm .
Program listing for Tuesday