The correspondence of EUV and white light observations of coronal mass ejections with SOHO EIT and LASCO

Abstract

For over two years of operation, the LASCO coronagraph and the EIT imaging telescope have conducted observing campaigns intending to provide continuous coverage of global coronal dynamic phemonena. These compatible observations, which we call the "CME Watch," have been used to further our understanding of CME initiation and propagation, and to provide advance warning of potential Earth-impacting eruptions. This paper includes a discussion of the EUV signatures of CME's in the inner corona and attempts to optimally combine the EUV and white light observations. One result of this effort is the determination that it is highly likely that LASCO definitively observes the vast majority of coronal mass ejections. While previous coronagraph missions have not been sensitive enough to detect weak eruptions, LASCO is capable of imaging even the faint "halo" CME's, which are our most accurate indicator of geospace-impacting eruptions.