Subject: SOHO/LASCO HALO CME 110922a

UCMEO 93001 10922 1630/
10922 61124 91422 0801/ 079// 223// 31290
10922 61009 81148 17808 11302 1112/
99999

PLAIN

SOHO/LASCO observed an asymmetric HALO CME on September 22, 2011.
This event is first seen in C3 at 14:22 UT where the event was in
progress and leading edge at 27 Rsun.  LASCO C2 and C3 missed the start
of the event while in a DSN contact gap period. The LASCO data will be
recovered for this event.

No time/height measurements can be made with LASCO at this time.


SDO/AIA 193 shows a long duration flare beginning 10:09 - 11:48 UT from a
region on the limb in the NE at [N08, E78].  This AR was recently registered
as AR 11302.  The flare produced a CME with dimming and wave extending over the
east hemisphere.  On disk in the northwest were 2 flares of AR 11295 at
09:57 (M1.1) and 10:21 UT which show emission and possibly related.
NOAA reports a X1.4 Xray flare of AR 11302 beginning 10:29-11:44 UT.

STEREO EUVI B 195 shows AR11302 on disk near center in NW quadrant with
a flare at 10:06-12:06 UT and a full disk wave following in the beacon data.
COR2 B shows a full symmetric halo at 11:25 UT.
Time/height measurements from COR2 B beacon data at 4 points with speed of
1289.7 km/sec at PA 283 degrees.

EUVI A shows flare at 09:55 UT and flare at 1025 UT from AR 11295 in NE and a
dimming (possible filament eruption) in SSW at 11:05-13:15 UT with emission.
COR2 A sees a full symmetric halo beginning 11:24 UT.
Time/height measurements from COR2 A beacon data at 5 pts with speed of
1219.7 km/sec at PA 74 degrees.
 
This is most probably the cause of the HALO event seen in LASCO.
   
The observation of this event is considered 'FAIR'. This CME is determined a FRONTSIDED event.

Images and movies and time/height information for this event is available on the web at:

http://umbra.nascom.nasa.gov/lasco/observations/halo/2011/110922a/

Best regards,

Kevin Schenk
Solar Heliospheric Observatory
EIT and LASCO Operations
NASA-Goddard Space Flight Center, USA

BT