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SOHO / SWAN Instrument

The Solar Wind Anisotropy instrument SWAN on board the ESA/NASA spacecraft SOHO is in operation since December 15, 1995 shortly after the launch of the spacecraft. It consists of two identical sensor units mounted on the +Z and -Z face of the spacecraft perpendicular to the SUn-pointing axis of SOHO. With their 2-axis periscopes each of them is mapping the Lyman alpha radiation of half the sky inside 24 hours.

Initially the instrument was operated according to a changing operations plan alternating routine full-sky mapping phases with special observations like high-resolution comet measurements, star observations for calibration purposes or solar wind velocity mapping with its inbuilt Doppler-shift filter.

Since 2009 the interactive support from the NASA ground segment at the Goddard Space Flight Center in Greenbelt, Maryland was reduced to save operation costs during the following extended mission. Accordingly SWAN is running in a completely automatical mode repeating its 24-hour full-sky mapping without interruption except for satellite management periods.

Automatic data analysis and status monitoring generates space weather observations and alerts in case of none-nominal behaviour which might need manual intervention.

The data are used for Solar wind monitoring, cometary research and 3-D- analysis of the Solar wind distribution inside the complete Solar system as a function of the Solar cycle phase.

SWAN Instrument Sensor Unit

SOHO / SWAN Sensor Unit FLight Model

Status Monitoring Display

Status Display at the Goddard Ground Segment