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Instrument: SWAN : Solar Wind Anisotropies
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Associated Platforms

Spectral/Frequency Information
Wavelength Keyword: Ultraviolet
Number Channels: 1
Spectral/Frequency Coverage/Range: 115-180 nm
Spectral/Frequency Resolution: 0.001 nm

Related Data Sets
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The SWAN (Solar Wind ANisotropies) instrument is one of twelve instruments
onboard SOHO (SOlar Heliospheric Observatory) satellite. It is a collaboration
between Finnish Meteorological Institute and Service d'Aeronomie. Technical
Research Centre of Finland was responsible for the construction, mechanics,
thermal design, and central processor of the instrument itself.

A solar Lyman alpha radiation is scattered by hydrogen atoms, which flow into
the solar system. The scattered radiation is called interplanetary Lyman alpha
radiation. SWAN observes interplanetary Lyman alpha radiation from all
directions of the sky. Usually SWAN observes three radiation maps of the whole
sky per week. In each map the radiation is strongest near the inflow direction
of the interstellar hydrogen gas. However, the overall picture of the sky has
changed considerably from the solar minimum 1996 to the solar maximum.
Theoretical results have shown that this kind of a change can be caused by the
solar wind proton flux which varies according to the distance to the
heliospheric current sheet.

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Online Resources

Instrument Logistics
Data Rate: 0.2 kbps
Instrument Start Date: 1995-12-02
Instrument Owner: Finnish Meteorological Institute
Service d'Areonomie, France