(Left) From top to bottom the panels show the evolution of the neutral density, the orbit decay, and the observed B_z component for an ICME event on November 20, 2003. In each panel, the red dashed line corresponds to the detection time of the minimum B_z and the green dashed line to the detected end time of the orbit decay. (Right) Histogram showing the time difference between the minimum of the B_z component detected at L1 (from real-time in-situ measurements) and the orbit decay reaching its maximum for all 116 ICME events.