LASCO Activity Report for
May 21, 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

LASCO will be participating with the coronal holes/streamer boundary study 
of UVCS/SUMER/CDS during May 17th through 23rd. It introduces only slight
modifications to the LASCO synoptic observation plan:

For C2: 6 hr cadence in orange filter pB (02:54 - 08:54 - 14:45 - 20:54 UT)
For C3: 12 hr cadence in orange filter pB (10:42 - 22:42 UT)


SOHO Telemetry Submode changed to Submode 5 on 2004/04/13 at 16:00 UT 
(SUMER began observing on 2004/04/14). SUMER campaign runs until 2004/06/17.
In other words, LASCO synoptic observation plan cadence remains the same
but the EIT CME watch images will be reduced to half-resolution (512x512)
during that period.

2004/05/20 (Thursday)

00:26 UT  W Limb	Ragged front that fades close to the inner edge of C3.
			CME signature in EIT Fe XII images right on W limb
			starting at ~ 23:12 UT on previous day.
			 
02:26 UT  N East	Big and bright ragged loop front, cavity, and trailing
			material. The mean plane-of-sky speed was ~ 437 km/s
			at PA 40 deg (based in C3 data), showing slight
			acceleration. The front spans ~ 70 deg from PA 7 - 77
			by 04:50 UT (C2). EIT Fe XII images show a filament
			eruption starting at ~01:25 UT, nearby (north of) NOAA 
			AR 0615, and developing toward NE.

04:26 UT  N West	Elongated loop front in the trailing material (at 
			roughly the central PA) of the event reported to start 
			at 20:06 UT on previous day.

05:26 UT  E Limb	Kind of 'reconexion' event. Separation point at ~ 3.5
			solar radii (material moving in both directions, i.e., 
			outward and falling down).

09:50 UT  NN West	Ragged loop front moving slightly toward N of event
			reported to start at 04:26 UT. Gusty outflow.

11:06 UT  W Limb	Diffuse loop front that fades close to the inner edge
			of C3.

17:06 UT  W Limb	Ragged loop front and apparently twisted trailing 
			material. It fades troughout C3.

23:26 UT  N West	Ragged expanding feature. Difficult to give an exact
			time of first appearance. No clear leading edge.
			Some structured outflow (faint) into next day.
 

2004/05/21 (Friday)

 	12:30 - 18:00 UT	Temporary DSN data Gap.