LASCO Activity Report for
February 2, 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

2005/02/01 (Tuesday)

06:06 UT  N West 	Very faint blob-like front starts to be visible at 
			~ 4.69 solar radii (PA ~ 315). An infalling structure 
			can be seen by the time, a little bit to N.

	  LASCO/EIT observed a complex 'full' Halo Event on 2005/02/01. 
	  Here is the report:

11:06 UT  N East	Very big and bright loop front. Close inspection shows
			that at least two different features are present: i) a
			ragged loop front developing toward NE (hereafter 
			Feature #1), and ii) a wider loop front, a little 
			behind, initially spanning from the N Pole up to the 
			E Limb with its brightest part above E (hereafter 
			Feature #2). By 11:30 UT, faint and diffuse extensions
			surround completely the C2 occulting disk. Feature #1 
			is first seen in C3 at 11:18 UT above the NE Limb,
			surrounded by a faint a diffuse envelope that, in the
			next frame at 11:42 UT, seems to extend all the way
 			from the E Limb, N Pole, up to the NW Limb; it 
			gradually subsides in the next frames. Feature #2 
			appears above the E Limb at 11:42 UT. By 12:42 UT, 
			the C3 occulting disk appears completely surrounded 
			by a rather circular front, which seems to be related 
			to Feature #2 rather than to Feature #1. The mean
			plane-of-sky speed (based on C3 data) of different 
			parts of the complex event is given below:
		      - LE of the faint and diffuse envelope surrounding 
			Feature #1 at PA 040 : 1300 km/sec (slightly 
			decelerated),
		      - LE of Feature #1 at PA 046 : 1046 km/sec (slightly
			decelerated),
		      - LE of Feature #2 at PA 112 : 700 km/sec (too ragged 
			the LE to have a precise measurement), and
		      - LE of the circular front that surrounds the C3 
			occulting disk by 12:42 UT at PA 298 : 495 km/sec 
			(too ragged the LE to have a precise measurement).
			No significant X-ray activity was reported by GOES by 
			the time. EIT 195 running difference images show no
			significant activity on the disk. However, signatures 
			of a backsided CME above the NE Limb starting at 
			10:36 UT can be clearly seen. In summary, the event 
			has therefore been determined as a complex Full Halo
			event, most probably backsided. Please keep in mind 
			that the global appearance of the event is given by 
			the contribution of at least two different components
			(apparently both backsided).

12:06 UT  S West	During the development of one of the components of the
			halo event, a small system of loops develops along the
			streamer. All along the day, the whole structure is
			being shifted toward the S Pole.   

17:54 UT  E Limb	In the halo aftermath, an elongated and ragged loop 
			front that fades very close to the inner edge of C3.
			System of faint loops moving outward superposed in the
			LOS, until early on next day.

18:30 UT  N East	Expanding loop front. By ~ 20:58 UT, a ragged loop 
			front develops moving faster, and thus disturbing the
			development of the previous loop front. Gusty outflow
			follows well into next day. Some infalling material
			on E Limb.

2005/02/02 (Wednesday)

03:54 UT  S Pole	Continuous development of a system of diffuse and
			expanding loop fronts.

05:30 UT  W Limb	Spray-like front followed at 06:54 UT by a bright 
			loop front developing slightly toward WNW. Only this
			loop front is discernible in C3.

10:30 UT  NN East	Diffuse and elongated loop front that fades throughout
			C2. Another one at 12:06 UT developing toward the N
			Pole.