Stereo Satllite sThe STEREO observatory is a NASA mission dedicated to the observation of the Sun from two point of views. One of its instrument, the Heliospheric Imager, is a novel instrument specialised to the observation of Coronal Mass Ejections (CME). It provides images of the heliosphere from 4 to 90 arcdeg in the visible wavelength range, allowing to track CME from the Sun outer corona up to the Earth orbit. STEREO was launched in October 2006 is still operational (


The Centre Spatial de Liège was involved in the design and on-ground calibration of the STEREO Heliospheric Imager, and in particular in its straylight design. The instrument achieved a very high rejection of the Sun brightness (~10^-14) allowing to reach a sufficient signal on noise ratio to detect the faint CME propagation over long distance from the Sun (





stereo instrument s     stereo CME s

 Heliopsheric Imager in the CSL Focal 3 chamber,

ready for straylight test


Example of STEREO Heliospheric Image

of a CME propoagating away from the Sun,

with the Milky Way and some planets (Jupiter, venus)

in background




Contact(s) : Jean-Philippe Halain