Solar alert

Issued on 2021 Oct 28 2129 UTC

A halo coronal mass ejection has been observed both by SOHO/LASCO-C2 and STEREO/Corr2 starting today at about 16:00 UT. Its true speed is estimated by Corr2 measurements to be around 650 km/s. NOAA Active Region (AR) 2887 produced an X1 flare at 15:48 UT and is the source of this CME. NOAA AR 2887's position at the central meridian and at the Solar south hemisphere, makes this halo CME almost certainly geo-effective. The arrival time is estimated to be in the first half of 31 Oct.

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