SOHO/LASCO Halo CME 20231207

Halo Alert: halo-message.20231208

UCMEO 93001 31211 2200/
31208 61612 82030 0002/ 360// 213// 30706
31208 ///// ///// ///// ///// /////
99999

PLAIN

SOHO/LASCO HALO CME December 8, 2023

C2 Start Time: 16:12 - 16:24 UT

C3 Start Time: 16:42 - 16:54 UT

Type of CME:
Asymmetric HALO CME — BACKSIDE
pa1: 000    pa2: 360       Total Width: 360 degrees

Velocity Measurements:

C2:   7 points     741.3 km/sec @ PA 311.43
C3:   10 points   689.3 km/sec @ PA 311.38
Average through both(C2/C3) fields: 706.0 km/sec Acceleration: -25.59 m/sec^2

COMMENT: LASCO C2/C3 show a very faint asymmetric halo CME. The CME emerges with a bright core in the NW. The halo CMEs source is a far-sided eruption, evidence of faint field line movement visible beyond the NW limb at 16:10 UT as best seen in SDO AIA 171.

STEREO Beacon Data COR2 A, shows a asymetric halo emerging from all directions with faint lines in the west and very faint lines in the east, starting between 16:23 - 13653UT. Preliminary time/height measurements gives a velocity of 581.6 km/sec @ PA 276.52 using 6 points of measurement.

Preliminary UCMEO velocity and position measurements are delivered first.
Images, movies, and time/height information for this event will be available at:

https://umbra.nascom.nasa.gov/lasco/observations/halo/2023/231208

Best Regards,

--James Tabourne

BT
[Images from original message are omitted here]

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