SOHO/LASCO HALO CME 120712

UCMEO 93001 20719 1520/
20712 61648 80006 2081/ 207// 123// 21360
20712 61551 81739 20619 11520 1112/
99999

PLAIN

SOHO/LASCO observed a HALO CME on July 12, 2012.  Event is first seen in C2 at
16:48 UT as a symmetric halo. There is only 3 frames in C2 until 17:12 UT where
Lasco safes and closed doors for SOHO spacecraft maneuvers 17:30-2:00 UT.
Once Lasco opened doors to resume observing, the event was in the C3 field
at 23:30 UT out to 27 Rsun.

Time/height measurements were marked at 3 points in C2 with speeds of
1360.4 km/sec at position angle 208 degrees. Speeds calculated through
the C2 field only give a velocity of 1360.4 Km/sec.

SDO AIA 193 shows a flare of AR 11520 located [S19, E06] beginning
16:06-17:39 UT.  A symmetric cme begins slightly before the
flare appears at 15:51 UT.  The event produces a dimming and a wave
on disk.

STEREO: HR data
COR2 A,  16:39 UT, a bright loop expands to an asymmetric halo (east). 
Preliminary time/height measure gives 1290.4 km/sec velocity at LE.
EUVI A 195, 15:45-17:05 UT a cme over the east limb.
COR2 B, 16:54 UT cme expands to an asymmetric halo (west) by 17:54 UT.
Preliminary time/height measure gives 1547.9 km/sec velocity at LE.
EUVI B 195, 16:05-17:00 UT cme over west limb.

NOAA reports an X1.4 Xray flare 15:37-016:49-17:30 UT from AR 11520 at location [S19,E06]

The observation of this event is considered 'POOR'. This CME is determined FRONTSIDED.

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

http://umbra.nascom.nasa.gov/lasco/observations/halo/2012/120712/

Best regards,

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

BT