LASCO Activity Report for
January 19, 2005 SOHO Science Daily Meeting

Event times are first frame seen in C2 camera unless otherwise noted.
These are preliminary observations for the daily SOHO science discussions.
Final analysis is reported on the Lasco CME list.
An archive of these reports is available.

Points Of Interest

2005/01/18 (Tuesday)

	LASCO Data still strongly degraded (snowstorm) by proton event on
	previous day associated to the X3.8 X-ray flare and Complex Full 
	Halo event. Until around 16:51 is practically impossible to discern 
	anything. Then, gradually subsiding.

17:14 UT  N West	Expanding loop front followed at 19:42 by a bigger
			expanding front.

17:37 UT  N East	Expanding ragged loop front that fades close to the 
			inner edge of C3.

2005/01/19 (Wednesday)

	LASCO/EIT observed a couple of events on 2005/01/19 that, considered
	together, look like an asymmetric and complex full halo event. 
	However, closer inspection show that apparently, at least two 
	different events occurred: i) a very asymmetric full halo CME, and 
	ii) a relatively slow asymmetric full halo event.

08:29 UT  N West	The event i) was first seen in C2 at 08:29 UT as a 
			very bright loop front above the NW limb surrounded by 
			a tenuous and diffuse excess intensity. By 09:06 UT, 
			the LE on NW already exited the C2 FOV, trailing 
			material coming out toward WNW followed by gusty 
			outflow. Streamers on NE and SW are pushed away by 
			the event. By that time, an apparently new faint and
09:28 UT  N East	ragged structure [ii)] develops towards NE. Faint
			extensions to E up to the  S Pole surround the C2
			occulting disk by 09:39 UT. Please also note that a
10:54 UT  N West	bright front starts developing toward NW. 
			The event i) is first seen in C3 at 09:16 UT above the 
			NW Limb as a clear loop front surrounded by a faint
			envelope, while event ii) is first seen appearing 
			above the NE Limb by 10:10 UT. By that time, the C3
			occulting disk is completely covered. The mean plane-
			of-sky speed of the different features involved was
			(based on C3 data):
		      * LE of the outermost front of the diffuse envelope
			surrounding the loop front i): ~ 1960 km/sec at PA 321.
		      * LE of the outermost feature of the bright loop i): ~ 
			1855 km/sec at PA 311.
		      * LE of ii) at PA 056: 614 km/sec
			GOES reported the following X-ray events by the time, 
			on NOAA AR 10720:
		      * an M6.7 X-ray flare (N16W53) between 06:58 - 07:55 UT
			with peak emission at 07:31 UT, 
		      * an X1.3 X-ray flare (N15W51) between 08:03 - 08:40 UT
			with peak emission at 08:22 UT, and
		      * an M2.7 X-ray flare (N17W52) between 10:19 - 10:29 UT
			with peak emission at 10:24 UT.
			EIT 195 images show a strong increase in intensity on 
			AR 10720 since around 07:17 UT peaking at 07:29 UT, 
			08:12 UT, and then again at 10:27 UT. After first
			peaking, the brightening is followed by ejection of
			material toward NW until around 09:00 UT. A big wave 
			can be seen mainly to NE, N, NW and SW of the AR. 
			Later, at 10:05 UT, more material can be seen ejected,
			this time mainly toward NE-NNE of the AR. This happen 
			at the same time as an apparently backsided CME on the 
			E Limb. It is difficult to associate temporally any 
			of the signatures seen in EIT with the event ii) 
			observed in C2/C3. Even though, considering the events
			on NOAA AR 10720, the X-ray flares, and the signatures 
			in C2/C3, the event can be be determined as a very
			asymmetric and complex 'full' halo event, frontsided. 

11:16 UT  EN East	Bright spray-like front.

14:02 UT  ES East 	Elongated and aparently twisted structure with a 
			diffuse front.