LASCO Activity Report for
May 20, 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.

2004/05/19 (Wednesday)

03:26 UT  W Limb	Faint `V-shaped` feature starting at ~ 3.30 solar radii.

03:26 UT  WS West	Ragged loop front followed at ~ 06:26 UT by a twisted
			structure. They fade throughout C3. Gusty outflow.
			Another twisted structure by ~21:26 UT (though the 
			time of first appearance is difficulte to give exactly).

08:26 UT  W Limb	Ragged front just N of previous event developing 
			slightly toward WSW.

09:26 UT  S East	Very faint asymmetric loop front. It is first seen at 
			~ 3.7 solar radii. It fades throughout C3.

11:50 UT  N Pole	Very faint loop front developing slightly toward NNE.
			It is first seen at ~ 3.8 solar radii. It fades in C3.

20:06 UT  NN West 	Big ragged loop front with structured interior. The 
			front spans ~ 105 deg, from PA 280 - 25 by 23:26 UT (C2).
			By 04:26 UT on next day an elongated loop front develops 
			roughly at the central PA of the event.

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.

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

09:50 UT  NN West	Ragged loop front.

11:06 UT  W Limb	Diffuse loop front.