SOHO/LASCO Halo CME 20260118

Halo Alert: halo-message.20260118

UCMEO 93001 60119 1715/
60118 61800 82048 1001/ 100// 333// 51154
60118 61727 81809 21422 14341 1112/
99999

PLAIN

SOHO/LASCO HALO CME January 18, 2026

C2 Start Time: 18:00 UT

C3 Start Time: 18:18 - 21:42 UT

Type of CME:
Full HALO CME — FRONTSIDE
pa1: 100      pa2: 100       Total Width: 360 degrees

Velocity Measurements:

C2 3 points 1104.3 km/sec @ PA 100
C3 7 points 1141.9 km/sec @ PA 100
Average through both fields: 1154.5 km/sec Acceleration: 33.45 m/sec^2.

COMMENT: A full HALO event can be seen in LASCO C2/C3 in the Southeast
                     quadrant @ 18:00 UT. NOAA reports that the CME is associated with
                     a X1.9 class solar flare in the Southeast quadrant located at [S14,E22].
                    SDO/AIA 193 shows opening lines commencing @ 17:27 UT in the Southeast
                    quadrant along with post-eruption arcades and dimming. An SEP event is
                    associated with the solar flare; starting at 22:50 UT, the proton event is greater
                    than the SWPC 10 MeV Warning Threshold.

STEREO BEACON Data
                 COR2 A shows a full HALO CME starting @ 17:53 - 19:38 UT.
                 Preliminary time/height measure shows 3 points - 1053.2 km/sec @ 108 deg.

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/2026/260118/

Best Regards,

--Taylor Lanier

BT

[Images from the original alert message are omitted here]

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SOHO/LASCO C2 Diff	SOHO/LASCO C3 Diff	SDO AIA 193 Angstrom

GOES-19 CORR1	SDO/AIA 193 Angstrom	STEREO/COR2 AHEAD

SOHO/LASCO C2	SOHO/LASCO C3	GOES-19 SUVI 131 Angstrom