Comment Section

Tracing the density enhancement visible on the 16th in HI2 backwards, there isn't really a corresponding Halo CME I can see in LASCO. I think what hit the Earth was the flank of an eruption late on the 14th of the west limb, though, at least in the coronograph FOV it doesn't seem fast enough. Nothing much is visible in STEREO B, so most of this is based on STEREO A data. It looks as though the only possibly Earthward CME entered the HI1 FOV in A around 03:00 UT on the 15th, and the only CME I can see in LASCO during that time is the western limb CME at around 22:00:00 on the 14th. (Hess)

Image Data

A combination of SWEPAM and MAG data from the ACE Satellite:

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The blue lines are an approximation of the CME cloud and the red line denotes the shock.