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]