Fast CME

2021/07/15

The MLSO K-Cor instrument observed a fast CME on July 15, 2021 beginning at 21:18:39 UT. The CME was moving at ~1100 km/sec as it left the K-Cor field of view. Trajectory plot shown on left (click to enlarge). The apparent width of the CME is ~270 degrees in the K-Cor subtraction images and may be wider. The largest GOES X-ray flare recorded at this time is a B7 flare, but it is not clear that it is associated with this event, which is consistent with the event originating on the far side of the solar disk. No increase is seen in the GOES proton flux.

The event appears to have originated from the far side of the Sun as seen from STEREO-A. It appears from behind the east limb of the Sun in STEREO-A EUV1 data. The CME is ~90 degrees wide (or wider) in the EUVI 195 data. An 'EIT' wave is also seen in the EUVI data, originating from behind the east limb and moving westward. STEREO-A is located -45 degrees heliographic longitude on July 15, 2021.

LASCO C2 first observed the CME at 21:36 UT. The event is a full halo in LASCO C2 as seen in the attached images.

The K-Cor CME observations show a black/white ‘fringing’ pattern in the subtraction images, as indicated by the red oval in this K-Cor image [insert thumbnail and link to K-Cor image with the red oval]. This pattern is most likely due to high winds at the observatory that day, that buffeted the spar and caused motions that can produce this fringing pattern in K-Cor images.


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