LASCO Activity Report for
May 16, 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

Medoc Campaign started on May 16.

May 12-14: IPS Measurements. During the IPS study, EIT will have regular
synoptics along with half resolution 195 CME watch.

On 2005/05/03 @ 19:06 UT SOHO Telemetry Submode changed to Submode 6.
It will be in Submode 6 until 2005/05/16 @ 12:00 UT. During that time,
EIT 195 CME watch at full resolution (1024x1024).

2005/05/13 (Friday)

	04:52 - 09:52 UT	NO LASCO C2 Data due to IPS "C3 only" 
				timeframe.

17:22 UT  HALO		Nice and bright full halo event. The event was first 
			seen in C2 at 17:22 UT already half way to the end of 
			the C2 FOV and completely surrounding the C2 occulting.
			The event looks brighter all above the NE Limb.
			Unfortunately, the LASCO Electronic Box (LEB) failed
			afterward, and therefore there are no more C2 images
			until 23:22 UT. For the same reason, there is a C3 
			data gap between 17:50 and 22:50 UT, and an EIT 195 
			data gap between 17:37 and 22:57 UT. The event was 
			first seen in C3 at 17:42 UT already as a very 
			symmetric and bright halo. Next C3 frame available was
			taken at 23:12 UT. By that time, the halo event is no
			longer visible in the C3 FOV. A rough estimation of 
			the mean plane-of-sky speed (rough because it was
			determined with the only 2 frames where the halo was
			seen) is as follows (LE defined as the position where 
			the intensity gradient is maximum): 
			- PA 000: ~  794 km/sec
			- PA 090: ~ 1020 km/sec
			- PA 180: ~  927 km/sec
			- PA 270: ~  915 km/sec
			A diffuse front can be seen over the North and South
			Poles ahead of the main structure of the event. If the 
			LE is considered as the outermost part of this diffuse
			front, the mean plane-of sky speed is:
			- PA 000: 1645 km/sec
			- PA 180: 1640 km/sec
			GOES reported a long duration M8.0 X-ray flare on NOAA 
			AR 10759 (N12E11) between 16:13 - 17:28 UT with peak
			emission at 16:57 UT. Associated proton event. The >10
			MeV proton flux exceeded the event threshold around 
			06:00 UT this morning. EIT 195 images show a strong
			brightening that starts to develop by 16:37 UT. A 
			dimming region develops to SW and NE of the AR. Also a 
			an important and symmetric EIT wave with epicenter 
			on the AR develops. In summary, the event has therefore
			been determined as a fast and strong Full Halo CME,
			frontsided, associated with a LDE M-class X-ray event 
			on NOAA AR 10759.

	17:50 - 22:50 UT	Non-recoverable LASCO Data Gap (C2 times)
				due to LEB (LASCO Electronic Box) crash.

2005/05/14 (Saturday)

	04:52 - 09:52 UT	NO LASCO C2 Data due to IPS "C3 only" 
				timeframe.

10:22 UT  N West	Faint elongated and expanding loop front already under
			development after data gap. It fades throughout C3.
			By 18:22 UT a diffuse fan-like front follows.

10:52 UT  N East	Faint elongated and expanding loop front. By 17:52 UT
			a spray-like front follows. It is difficult to say
			whether this event is an independent event or part
			of the event reported in previous entry.

20:56 UT  WS West	Bright and big ragged loop front with apparently
			twisted interior. Faint extensions to N. Early on next
			day, C2 images show an increase of the proton storm 
			(>10 MeV) under development since LDE M-class X-ray 
			event and halo on 2005/05/13. By 06:06 UT on next day,
			the proton storm signature in C2 subsides. EIT 195 
			images show bright ejecta toward SW from nearby AR 
			10758 by 20:37 UT. The CME extends to SSW by 21:10 UT.
			GOES reported a C2.8 X-ray flare form NOAA AR 10758
			between 20:18 - 22:36 UT with peak emission at 
			20:58 UT.

NOTE: 
NOAA AR 10758 produced other several C-class X ray flares during the day:
- C1.1 peaking at 13:26 UT (S10W90)
- C4.0 peaking at 15:06 UT (S09W90)
- C3.5 peaking at 15:57 UT (S10W90)

2005/05/15 (Sunday)

NOTE:
NOAA AR 10758 continue producing C class events until dissapearing behind 
the limb. Last C-class event from 10758 peaking at 09:42 UT

10:26 UT  S West	Ragged front along streamer. By the time, a kind of
			reconexion event develops a little bit to N. A ragged
			loop with the front looking like a ragged blob follows
			by 13:26 UT. Infalling material on W.

21:50 UT  NN West	Slow development of a system of loops. It is difficult
			to give an exact time of first appearance.

23:26 UT  S Pole	Extremely faint and diffuse wide loop front. It fades
			throughout C2. GOES reported a M3.5 X-ray flare from
			NOAA Ar 10763 (S16E15) between 22:27 - 22:42 UT with
			peak emission at 22:36 UT. EIT 195 shows a wave, and a
			dimming region to S, WNW, and W of the AR. A C2.1 X-ray
			flare follows from the same Ar (S16E20) between 23:46 - 
			00:29 (+1) UT with peak emission at 00:03 UT (on 
			May 16). 
NOTE:
Please note that 10763 produced another four C-class X-ray flares earlier in 
the day (if any signature of C2 events associated to them, too faint to 
be discernible).

2005/05/16 (Monday)

03:26 UT  S Pole	Another extremely faint (barely discernible) and 
			diffuse loop front. Brightening on SE that could be 
			part of. Nothing can be discerned in C3. GOES reported 
			an M1.4 X-ray flare from NOAA AR 10763 (S16E18) 
			between 02:33 - 02:50 UT with peak emission at 02:43 
			UT. EIT 195 shows a loop brightening at the center of 
			the AR by 02:48 UT. Loops to S of the AR disappear.