There is no data available on the purpose of the flight or the experiments performed. Below there is a link to the only known reference.
Balloon launched on: 2/25/1999 at 10.48
Launch site: European Space Range, Kiruna, Sweden
Balloon launched by: Centre National d'Etudes Spatiales (CNES)
Balloon manufacturer/size/composition: Montgolfier Infrared 45.000 m3
End of flight (L for landing time, W for last contact, otherwise termination time): 2/25/1999
Campaign: THESEO (Third European Stratospheric Experiment on Ozone) take place during 1998-99 to improve the understanding of the causes of ozone depletion over Europe and other mid-latitude regions. It involved more than 400 scientists from over 20 countries.
Balloon burst at launch
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