To accurately predict the space weather effects of coronal mass ejection
(CME) impacts at Earth one must know if and when a CME will impact Earth, and
the CME parameters upon impact. Kay et al. (2015b) presents Forecasting a CME's
Altered Trajectory (ForeCAT), a model for CME deflections based on the magnetic
forces from the background solar magnetic field. Knowing the deflection and
rotation of a CME enables prediction of Earth impacts, and the CME orientation
upon impact. We first reconstruct the positions of the 2008 April 10 and the
2012 July 12 CMEs from the observations. The first of these CMEs exhibits
significant deflection and rotation (34 degrees deflection and 58 degrees
rotation), while the second shows almost no deflection or rotation (<3 degrees
each). Using ForeCAT, we explore a range of initial parameters, such as the CME
location and size, and find parameters that can successfully reproduce the
behavior for each CME. Additionally, since the deflection depends strongly on
the behavior of a CME in the low corona (Kay et al. (2015a, 2015b)), we are
able to constrain the expansion and propagation of these CMEs in the low
corona.Comment: accepted in Ap
