SOHO/LASCO Halo CME 20260111

Halo Alert: halo-message.20260111

UCMEO 93001 60112 2115/
60111 62224 80136 0892/ 089// 333// 51075
60111 62154 82316 21389 ///// 1222/
99999

PLAIN

SOHO/LASCO HALO CME January 11, 2026

C2 Start Time: 22:24 UT

C3 Start Time: 22:54 – 02:18 UT

Type of CME:
Partial HALO CME — BACKSIDE
pa1: 89      pa2: 89       Total Width: 360 degrees

Velocity Measurements:

C2 3 points 1034.3 km/sec @ PA 89
C3 7 points 1189.0 km/sec @ PA 89
Average through both fields: 1075.3 km/sec Acceleration: 68.48 m/sec^2.

COMMENT: A partial HALO event can be seen in LASCO C2/C3 in the Southeast
                      quadrant @ 22:24 UT. NOAA reports that the CME is associated with
                      a M3.3 class solar flare in the Southeast limb located at [S13,E89].
                     SDO/AIA 193 shows opening lines associated with the long duration
                      event starting @ 21:54 UT in the Southeast limb along with post-eruption
                     arcades where supra-arcade downflows can also be seen.

STEREO BEACON Data
Due to data gaps from 19:38 - 02:53 UT, preliminary time/height measurements could not be performed at this time.

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/2026/260111/

Best Regards,

--Taylor Lanier

BT
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SOHO/LASCO C2 Diff	SOHO/LASCO C3 Diff	SDO AIA 171 Angstrom

[S13,E89]	SDO/AIA 193 Angstroms Diff	STEREO/COR2 AHEAD

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