SOHO/LASCO Halo CME 20211028

Halo Alert: halo-message.20211028

UCMEO 93001 11028 1840/
11028 61548 91730 2231/ 222// 333// 41609
11028 61518 81551 30526 12887 1112/
99999

PLAIN

SOHO/LASCO HALO CME October 28, 2021

C2 Start Time:     15:48 UT

C3 Start Time:        16:06 - 17:30 UT (in progress)

Type of CME:
Asymmetric HALO CME — FRONTSIDE
pa1: 223      pa2: 222       Total Width: 360 degrees

Velocity Measurements:

C2    3 points    1572.4 km/sec @ PA 222
C3    5 points    1706.7 km/sec @ PA 224
Average through both fields:     1609.2 km/sec Acceleration: 111.05 m/sec^2.

COMMENT:       AIA 193 shows a long duration flare of AR 12887 at location [S26, W05]
            15:18-15:51 UT. The event produces an EUV wave propagating
            across the face of the disk followed by a bright post loop arcade.


            STEREO Beacon Data
            COR2 A, 15:23 - 17:38 UT; shows a CME from the South West.
            Preliminary time/height measure gives 1004.6 km/sec @ 234 degrees.

NOAA/GOES reports a X1.0 class X-ray flare of AR12887 15:17/15:35/15:48 UT.

This is a SEP (Solar Energetic Particle) event.
GOES shows proton flux levels in > 50 MeV exceeds 10 pfu (solar storm levels).

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/2021/211028/

Best Regards,

--Kevin Schenk

BT

[Images from the original alert message are omitted here]