The 2005 January 20 CME first appeared at 06:54:05 UT at a height of
4.48 Rs in the C2 field of view. The LASCO image had already begun to
be contaminated by the SEPs arriving at the SOHO spacecraft. The later
two images in the C3 FOV do not show the CME leading edge well. The
measured heights therefore may not correspond to the leading edge, but
to some brighter innner parts, thus underestimating the speed. The
speed given here therefore is to be taken as a lower limit. A detailed
analysis of the event including the EIT data can be found in Gopalswamy et al. (2005), which estimates
a sky-plane speed of 3242 km/s at 06:54 UT.