  The determination of delay times of solar wind conditions at the sunward
libration point to effects on Earth is investigated using mutual information.
This measures the amount of information shared between two timeseries. We
consider the mutual information content of solar wind observations, from WIND,
and the geomagnetic indices. The success of five commonly used schemes for
estimating interplanetary propagation times is examined. Propagation assuming a
fixed plane normal at 45 degrees to the GSE x-axis (i.e. the Parker Spiral
estimate) is found to give optimal mutual information. The mutual information
depends on the point in space chosen as the target for the propagation
estimate, and we find that it is maximized by choosing a point in the nightside
rather than dayside magnetosphere. In addition, we employ recurrence plot
analysis to visualize contributions to the mutual information, this suggests
that it appears on timescales of hours rather than minutes.
