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EP: Extraterrestrische Physik

EP 3: Sonne und Heliosph
äre

EP 3.6: Talk

Monday, March 18, 2002, 17:50–18:05, HS 15

The Ulysses fast latitude scan at solar maximum:COSPIN/KET observations — •Bernd Heber¹, Alain Raviart², Philippe Ferrando², Constantinos Paizis³, Giovanna Sarri³, Arik Posner⁴, Horst Kunow⁴, Reinhold Müller-Mellin⁴, and Gerd Wibberenz⁴ — ¹Fachbereich Physik, Universität Osnabrück, Germany — ²DAPNIA/Service d’Astrophysique, CEA Saclay, France — ³CNR-IASF, Milano Italy — ⁴IEAP, CAU, Kiel, Germany

Ulysses, launched in October 1990, began its second out of ecliptic orbit in December 1997, and its second fast latitude scan in September 2000. In contrast to the first perihelion in 1994/1995, solar activity now is close to maximum. It is important to note that, in addition to the difference in solar activity, prior to or during the second scan the solar magnetic field reversed. While the first latitude scan mainly gave a snapshot of the spatial distribution of galactic cosmic rays, the second one is dominated by temporal variations. Solar particle increases are observed at all heliographic latitudes, including events that produce >250 MeV protons and 50 MeV electrons. Using >50 MeV proton observations from the EPHIN instrument, this time we find no significant latitudinal gradients. Furthermore, the differences between the two scans are also reflected in charge sign dependent variations.