Subject: SOHO/LASCO HALO CME 120927 BACKSIDED

UCMEO 93001 20927 1730/
20927 61012 81442 2422/ 243// 323// 41546
20927 60925 81055 ///// 11574 1112/
99999

PLAIN

SOHO/LASCO observed a HALO CME on September 27, 2012.  Event is first seen
in C2 at 10:12 UT as a loop surfacing over the Southwest limb with cavity
and core. The event expands to a full asymmetric halo CME by 10:36 UT.
The event continues into the C3 field beginning 10:42 to 14:42 UT leaving
the C3 field at 30 Rsun in the West.

Time/height measurements were marked to 3 points in C2 with speeds 
of 1527.5 Km/sec at position angle 226 degrees. The event is marked to 10 points 
in C3. Speeds average through both fields to 1534.0 Km/sec at PA 2439 degrees.  
Acceleration -30.19 m/sec^2.

SDO/AIA : n/a

STEREO: Beacon data
COR2 A, 10:24 UT asymmetric halo with cavity and core in the West .
Preliminary time/height measure gives 1247.1 km/sec velocity at LE.
EUVI A 195, 09:25-10:55 UT.  CME erupts shortly before a large flare.  The
AR is located on disk at [S31, W158]. Event produces a dimming and nice wave,
and finishes with bright post loop arcade.
This appears to be the activity of NOAA numbered region AR11574.
COR2 B, 10:25 UT partial halo east/southeast.
Preliminary time/height measure gives 1489.9 km/sec velocity at LE.
EUVI A 195, shows a flare with CME on limb in SE 09:36-10:56 UT.  Post arcade
rises over limb.

The observation of this event is considered 'GOOD'. This CME is determined a BACKSIDED 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/2012/120927/

Best regards,

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

BT