  A new, automated method of detecting coronal mass ejections (CMEs) in three
dimensions for the LASCO C2 and STEREO COR2 coronagraphs is presented. By
triangulating isolated CME signal from the three coronagraphs over a sliding
window of five hours, the most likely region through which CMEs pass at 5 solar
radii is identified. The centre and size of the region gives the most likely
direction of propagation and approximate angular extent. The Automated CME
Triangulation (ACT) method is tested extensively using a series of synthetic
CME images created using a wireframe flux rope density model, and on a sample
of real coronagraph data; including halo CMEs. The accuracy of the angular
difference between the detection and true input of the synthetic CMEs is 7.14
degrees, and remains acceptable for a broad range of CME positions relative to
the observer, the relative separation of the three observers and even through
the loss of one coronagraph. For real data, the method gives results that
compare well with the distribution of low coronal sources and results from
another instrument and technique made further from the Sun. The true three
dimension (3D)-corrected kinematics and mass/density are discussed. The results
of the new method will be incorporated into the CORIMP database in the near
future, enabling improved space weather diagnostics and forecasting.
