LASCO Activity Report for
September 03, 2004 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

2004/09/02 (Thursday)

	  N West	Gusty outflow.

	  ES East	Infalling material.

01:31 UT  W Limb	Blob-like front becomes discernible.

09:30 UT  WN West	Diffuse and elongated ragged loop front.

14:54 UT  W Limb	Small ragged front developing slightly toward WSW. It
			fades throughout C2.

17:30 UT  WS West	System of elongated ragged loop fronts.

2004/09/02 (Friday)

00:30 UT  NW    Extremely faint and diffuse front surrounding almost the C2
		occultor. SEE description of event reported to start at 00:40 UT.

00:30 UT  WSW	Bright ragged feature. SEE description of event reported to 
		start at 00:40 UT.

00:40 UT  SE	Almost circular front develops as a 'full' halo CME. The 'halo'
 		event (hereafter Event #1) was first observed in C2 above the 
		SE Limb extending up to the SW Limb. Please note that already 
		by 00:30 UT an extremely faint and diffuse front is also seen
		surrounding almost completely the C2 occultor. Closer inspection
		of the development of this faint front shows that what at first
		glance seemed only one front are in fact two: one moving out
		mainly toward NW (Event #2), and another one developing mainly
		toward SE (Event #3). Starting also at 00:30 UT a ragged feature
		(brighter than the other features described above) develops
		toward WSW - SW (Event #4), which is followed at 03:06 by a
		twisted feature. Also at that time, an elongated ragged feature
		can be seen developing toward NE (Event #5).The five events are
		first seen in C3 by 01:42 UT: Event #1 just barely seen above 
		the SW Limb, Event #2 (on NW) and #3 (on SE) further out, Event
		#4 above the WSW Limb as a bright ragged feature, and Event #5
		just above the NE Limb.  
 		For reference, the mean plane-of-sky speed for the LE of the
		different events is shown below (based on C3 data):
		Event #1: PA 128 --> 412 km/sec (practically no acceleration)
		Event #2: PA 291 --> 484 km/sec (very diffuse LE)
		Event #3: PA 086 --> 599 km/sec (very diffuse LE)
		Event #4: PA 241 --> 388 km/sec (practically no acceleration)
		Event #5: too difficult to track it accurately, but its
		speed is in the 350-450 km/sec range.
		GOES did not record any significant X-ray activity by the time. 
		On the other hand, EIT Fe XII images show the lift-off of a 
		filament located around equatorial latitudes, past half way to
		the W Limb, starting at around 18:00 UT. This signature is 
		likely to be the EIT counterpart of either what we called Event
		#4 or the twisted feature coming behind. Other than that, there
		is no other visible signature on the disk that could be related
		to the other events mentioned above. By the time of writing is
		not clear whether Events #2 and #3 are related to any of the
		other two events or are monster of a diferent nature. As for
		Event #1, it has therefore been determined as a 'full' HALO CME,
		backsided. 

10:30 UT HALO   Another 'full' Halo CME starts developing.