Halo CME Mail

Date: Mon, 1 Nov 2004 10:42

From: Guillermo Stenborg

Subject: Complex frontsided activity on 2004/10/30; 'full' halo CME



UCMEO 93001 41101 1430/
41030 61654 80218 0001/ 360// 623// 20670
41030 61618 81637 42813 10691 1122/
99999
 
PLAIN
 
BT 

LASCO/EIT observed complex frontsided activity on 2004/10/30, one
of the events giving origin to an asymmetric 'full' halo CME. 
A brief description of the main events seen on LASCO images follows:

- 05:30 UT, on WNW, a faint and big ragged front already under 
development after a LASCO data gap (02:30 - 05:30 UT).   

- 06:54 UT, on W, a bright and wide ragged loop front. By 07:31 UT, 
faint circular extensions are discernible all above the E - SE - S 
Limb. The extensions are not discernible in C3. 

- 09:30 UT, a big expanding loop front follows right above the W Limb.

- 12:30 UT, a bright loop front developing mainly toward WSW follows.
Circular extensions on NW and all above the E - SE - E Limb are 
discerned. The extensions are not visible in C3.

- 15:06 UT, a relatively small ragged loop front on W.

- 16:54 UT, another bright ragged loop front developing slightly toward 
WSW. By 17:30 UT, faint circular extensions are discernible above the 
E - SE - E Limb, and also on NW. An even fainter and diffuse front 
seems to develop also on NE. By 18:18 UT, the event looks like a very 
asymmetric 'FULL' HALO CME in C3. Note that the ragged loop front is
first seen in C3 above the W Limb at 17:18 UT. The mean plane-of-sky
speed of the LE at PA 262 was ~670 km/sec (based on C3 data). 

- 18:06 UT, a relatively small and asymmetric loop front.

- 20:30 UT, a diffuse and asymmetric loop front develops slightly toward 
WNW.     
                        
The activity reported is most likely associated to lot of X-ray activity 
on NOAA AR 10691 since late on previous day. In particular, GOES reported
(on 2004/10/30) the following X-ray flares:
- C9.7 (N14W19) between 00:39 - 00:53 with peak emission at 00:49 UT,
- M3.3 (N13W20) between 03:23 - 03:37 with peak emission at 03:33 UT,
- M4.2 (N13W22) between 06:08 - 06:22 with peak emission at 06:18 UT,
- C5.5 (N16W22) between 06:55 - 07:05 with peak emission at 07:01 UT,
- M3.7 (N14W24) between 09:09 - 09:30 with peak emission at 09:28 UT,
- C7.2 (N13W25) between 10:20 - 10:41 with peak emission at 10:35 UT,
- C1.0 (N12W26) between 11:17 - 11:27 with peak emission at 11:22 UT,      
- C2.6 (N12W27) between 13:59 - 14:10 with peak emission at 14:06 UT,      
- M5.9 (N13W28) between 16:18 - 16:37 with peak emission at 16:33 UT 
The last one (M5.9) is the one most likely associated to the HALO CME 
reported to start at at 16:54 UT. Please also note that there was a C3.7 
X-ray flare from NOAA AR 0687 (N13W59) between 12:45 - 13:03 UT with peak 
emission at 12:51 UT.   
         
On the other hand, EIT 195 images show a strong brightening on NOAA AR
10691 starting at 16:24 UT, and an intensity disturbance afterward 
traveling all its way mainly toward SW.

In summary, the event reported to start at 16:54 UT (C2 time) has 
therefore been determined as an asymmetric 'full' halo CME, frontsided.

Movies and images of the event will shortly be made available at: 

ftp://ares.nrl.navy.mil/pub/lasco/halo/20041030


Best wishes,
	Guillermo Stenborg
  

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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
++