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PLAIN


SOHO/LASCO  HALO CME October 18, 2017  

C2 Start Time:   05:48 UT

C3 Start Time: 06:06 - 10:06 UT  

Type of CME:
Asymmetric HALO CME — BACKSIDE
pa1:  127      pa2:  126       Total Width:  360 degrees

Velocity Measurements:

C2 3 points  1936.3 km/sec @ PA 127
C3 6 points  1618.1 km/sec @ PA 127  
Average through both fields:   1708.2 km/sec  Acceleration:   

COMMENT:    STEREO Beacon EUVI 195 [data gap 03:35-08:05 UT] 
An event in progress at 08:05 UT shows a post loop arcade 
along a filament channel centered at location [S09, E125] 
08:05-13:45 UT.  

SDO AIA 193 shows an eruption 05:33-06:54 UT over the limb 
producing wave material seen on disk across the south hemisphere.
Ejecta is seen 05:36-05:45 UT in both 193 and 304A filters.
 
LASCO.  The event seen in C2 and C3 has 2 parts. The event listed 
above (A) is a full asymmetric HALO in LASCO beginning at 05:48 UT.
The 2nd event (B) close in time beginning 07:48 - 13:30 UT is involved
but is not a HALO in LASCO. 
Preliminary time/height measure gives 1014.7 km/sec @ 080 degrees.
Increased proton flux in seen in the LASCO field of view.

STEREO Beacon Data
COR2 A, [data gap 03:39-07:54 UT]. COR A missed the first HALO event
begging 05:48 in the LASCO C2 telescope.
The 2nd event is seen in COR2 beginning 07:54 - 10:24 UT showing an 
asymmetric HALO CME.  
Preliminary time/height measure gives 952.0 km/sec @ 234 degrees.
 
 
Preliminary UCMEO velocity and position measurements will be delivered first. 
Images, movies, and time/height information for this event will be available at: 

https://umbra.nascom.nasa.gov/lasco/observations/halo/171018/


Best Regards,

--Kevin Schenk

BT