Subject: SOHO/LASCO HALO CME 120928

UCMEO 93001 20928 1214/
20928 60000 80630 3001/ 299// 323// 31035
20927 62246 80024 43109 ///// 2112/
99999

PLAIN

SOHO/LASCO observed a HALO CME on September 28, 2012.  Event is first seen
in C2 at 00:00 UT on the Northwest. A full asymmetric HALO develops with cavity
and core by 00:36 UT.  The event continues into the C3 field beginning
00:18 to 06:30 UT leaving the C3 field at 30 Rsun in the West.
Increased proton flux is seen in the white light images.

Time/height measurements were marked to 4 points in C2 with speeds 
of 1176.2 Km/sec at position angle 300 degrees. The event is marked to 9 points 
in C3. Speeds average through both fields to 1034.8 Km/sec at PA 300 degrees.  
Acceleration -44.42 m/sec^2.

SDO/AIA : 193A and 304A show activation along a filament beginning 9/27 21:24 UT
The filament is located on disk in the Northwest at [N09, W31] west of and
adjacent to AR11577. The filament erupts and a dual ribbon flare is produced
22:42-00:24 UT with a dimming and a wave across the west hemisphere.
The event finishes with bright post arcade.

STEREO: Beacon Data
COR2 A, 17:40-02:25 UT data gap. partial halo over the East.  CME out of the FOV
at first frame.
EUVI A, 15:35-02:55 UT data gap.  n/a.
COR2 B, 15:39-03:24 UT data gap. Partial halo over the West out to edge of FOV.
EUVI B, No EUVI data after 14:46 UT.  n/a.

NOAA reports a C3.7 Xray flare 23:36/23:57/00:34 UT which is associated to the ribbon event.
GOES13 shows a rise in proton flux.  Particles >10MeV peaked above storm levels.

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/2012/120928/

Best regards,

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

BT