Stereoscopic analysis of STEREO/SECCHI data for CME trajectory determination

►The coronagraphs on the twin Solar TErrestrial RElations Observatory (STEREO) spacecraft allow stereoscopic viewing of coronal mass ejections (CMEs). ►The technique of tie-pointing and triangulation is used to determine the trajectories (velocity and propagation angle) of CMEs. ►CMEs are optically thin and the images from the two spacecraft show different apparent leading edges and the error cause by this is analyzed. ►The ranges where the technique is reliable and where it is not are discussed.