Halo CME Mail

Date: Mon, 26 Jul 2004 12:13

From: Guillermo Stenborg

Subject: 'Full' Halo CME on 2004/07/25, frontsided



UCMEO 93001 40726 1615/
40725 61430 82318 0001/ 360// 233// 31228
40725 61318 81643 43004 10652 1222/
99999
 
PLAIN
 
BT 

LASCO/EIT observed a 'full' Halo CME on 2004/07/25. The event
was first seen in C2 at 14:30 UT developing as an extremely 
bright loop front, preceded at 13:31 UT by a faint kind-of 
asymmetric loop front (quickly surpassed by the loop front). By 
15:30 UT, faint extensions in the western hemisphere, and even 
fainter ones on the N Pole surround the C2 occultor. A fainter 
second front is seen to appear later above the SW Limb in C2, 
at 15:54 UT. Gusty outflow follows at PA around 225. The event 
is first seen in C3 at 15:18 UT above the SW Limb. By 15:52 UT, 
faint extensions already surround the C3 occultor. For reference, 
the mean plane-of-sky speeds at several PA is given below (based 
only on C3 data): 

PA 005:   814 km/s
PA 145:  1228 km/s 
PA 224:  1081 km/s
PA 262:  1167 km/s

GOES recorded by the time a couple of M- and one C-class X-ray 
flares on NOAA AR 0652:
C2.1 (N04W29) between 13:18 - 13:32 UT; Peak at 13:25 UT
M2.2 (N04W30) between 13:37 - 13:55 UT; Peak at 13:49 UT
M1.1 (N08W33) between 14:19 - 16:43 UT; Peak at 15:14 UT

Among significant features observed in Fe XII running difference 
images it is worth to mention: i) a moderate brightening at 13:26 UT 
on NOAA AR 0652, signature of the C2.1 X-ray flare; ii) a strong 
brightening on the same AR at 13:48 UT (signature of the M2.2 X-ray 
flare) with associated ejecta of material toward SW (ejecta that 
seems to disturb -push toward S- some loops on SW of the AR 0652); 
and iii) another couple of brightenings in the same AR peaking by 
15:00 UT and 16:00 UT (most likely signatures of the relatively 
long duration M1.1 X-ray event). Please also note that at 14:48 UT, 
an expanding system of loops develops on the WSW Limb, apparently
with its source just behind the limb (by 16:00 UT post-flare loops 
can be discerned raising from behind the limb).

The event has therefore been determined as a complex 'full' halo 
CME, frontsided. 

Images and movies of the whole set of events will shortly be made 
available at: 

ftp://ares.nrl.navy.mil/pub/lasco/halo/20040725


Best wishes,
	Guillermo Stenborg
  
++
Dr. Guillermo A. Stenborg   
SOHO-LASCO Operations Scientist,                                           
CUA, MC 682.3, Bldg 26, Rm 001,   F: +1-301-286-0264         
NASA Goddard Space Flight Center,
Greenbelt, MD 20771.              P: +1-301-286-2941

e-mail: stenborg@kreutz.nascom.nasa.gov
++