SOHO/LASCO Halo CME 20120309ab

Halo Alert: halo-message.20120309ab

UCMEO 93001 20309 1730/
20309 60414 90835 2921/ 291// 333// 20863
20309 60327 80433 40317 11429 1112/
99999

PLAIN

SOHO/LASCO observed a HALO CME on March 9, 2012. Event is first seen in
C2 at 04:14 UT as a symmetric halo with a second event in close succession
seen by 04:38 UT. There is a substantial amount of proton emission in the
lasco fields from the March 7 event and makes the leading edge of the halo
difficult to track. The event continues into the C3 field beginning
04:44 to 08:35 UT out to 20 Rsun at last frame before a temporary data gap.

Time/height measurements were marked to 4 points in C2 with speeds of 1029.4 Km/sec
at position angle 292 degrees. The event is marked to 10 points in C3. Speeds average
through both fields to 863.3 Km/sec at PA 292 degrees. Acceleration -40.86 m/sec^2.
A second set of measurements were taken over the east. C2 marked at 4 points with
speeds of 1157.7 km/sec at pa 78 degrees. C3 marked at 6 points. Averaged speeds
through both fields 948.1 km/sec at pa 78. Acceleration of -49.65 m/sec^2.

SDO/AIA 193 shows a flare of AR 11429 located at [N17,W03] beginning 03:27-04:33 UT.
A symmetric wave and dimming begins at 03:39 UT which spans the front of the disk.

STEREO: Beacon data
COR2 B, First seen at 04:25 UT with LE at 5.3 Rsun in the west. An expanding loop CME
with cavity and core develops to a full asymmetric halo over the west hemisphere.
Preliminary time/height measure gives 737.9 km/sec velocity at LE.
EUVI B, 03:36-04:26 UT a cme over the west limb.
COR2 A, Data gap starts at 03:54 UT. n/a
EUVI A, 03:35-03:55 UT (03:55 UT last frame before gap) expanding cme over east limb.

NOAA reports a M6.3 X-ray flare of AR 11429 03:22-04:18 UT.

The observation of this event is considered 'POOR'. 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/2012/120309ab/

Best regards,

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

BT

[Images from the original alert message are omitted here]

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SOHO/LASCO C2 Diff	SOHO/LASCO C3 Diff	SDO/AIA 193 Angstrom

STEREO/COR2 BEHIND Diff	SDO/AIA 193 Angstroms Diff	STEREO/EUVI AHEAD Diff

SOHO/LASCO C2	SOHO/LASCO C3	SDO/AIA 304 Angstrom