LASCO Activity Report for
January 18, 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

2005/01/14 (Friday)

05:30 UT  WS West	Faint front along streamer. It fades throughout C3.

06:54 UT  SS West	Kind of diffuse and elongated front that quickly fades.

11:30 UT  WS West	Ragged front along streamer that fades throughout C3.

17:06 UT  WS West	Ragged front along streamer. Very faint (rather) 
			circular extensions around the C2 occulting disk by
			around 18:30 UT. No visible signatures in C3. GOES 
			reported an M1.0 X-ray flare on NOAA AR 10718 (S06E02)
			between 16:02 - 16:14 UT with peak emission at 16:06 UT.
			EIT 195 images show, by 16:12 UT, a brightening on
			both sides of the neutral line of the AR, followed by
			an small dimming region to N of the AR.
	  

2005/01/15 (Saturday)

	NOTE:   LASCO did not show evidence of any halo-like event associated 
		with the X1.2 X-ray flare on NOAA AR 10720 (N14E08) that 
		occurred between 00:22 - 01:02 UT with peak emission at 
		00:43 UT.

06:30 UT  N Pole	Very bright loop front above the N Pole. A faint and
	  (HALO)	diffuse envelope (shock?) can be seen all around the 
			loop front. By 06:54 UT, the C2 occulting disk is
			completely covered, the LE of the event on N being
			already out of the C2 FOV. The event is first seen in 
			C3 at 16:42 UT above the N Pole, the C3 occulting disk
			being completely covered by 07:42 UT. It develops 
			pretty fast: the LE on N crossed the end of the C3 
			FOV by ~ 09:42 UT. The mean plane-of-sky speed of the 
			LE (outermost front of the diffuse envelope ahead of 
			the loop-like feature) at PA 002 was ~2150 km/sec 
			(as measured on C3 in only 3 frames, then out of the
			FOV). For the sake of completeness, the mean plane-of-
			sky speed of the LE of the loop-like feature at PA 0 
			was ~1850 km/sec (based on C3 data, only 3 frames).
			GOES reported multiple M-class flares and a couple of
			X-ray flares on NOAA AR 10720 during the day. In
			particular, an M8.6 X-ray flare occurred at N16E04
			between 05:54 - 07:17 UT with peak emission at 06:38 
			UT, is the one most likely associated to the signatures
			observed on C2/C3, which happened just after a compact
			M8.4 X-ray flare on the same AR (N14E06) between 
			04:26 - 04:36 UT with peak emission at 04:31 UT. EIT 
			195 images show signatures of the event along and N 
			of the (east-west) neutral line of AR 10720 between 
			06:00 - 07:13 UT. An intensity disturbance (wave) is 
			seen mainly to N and NW of the AR, including the
			activation of a large filament channel (FC). In 
			summary, the event has therefore been determined as 
			an asymmetric 'full' halo event, frontsided. 
			Expanding loop-like structures follow on NNW, most 
			likely related to continued X-ray activity on AR 10720.

14:54 UT  WS West	Bright ragged loop front with apparently twisted 
			trailing structure. GOES reported an M3.2 X-ray flare
			on NOAA AR 10718 (S08W12) between 14:08 - 14:39 UT
			with peak emission at 14:23 UT. EIT 195 images show
			a wave on disk toward S, SW, and NW of the AR after
			a brightening at 14:36 UT.

23:06 UT  N-NW-E Limb	Very bright loop front covering practically the whole 
	  (HALO)	NW quadrant. The next C2 frame (23:30 UT) shows the 
			C2 occulting disk completely covered. Early on next day 
			a proton storm can be seen developing in the C2 FOV 
			(also C3). The event is first seen in C3 at 23:18 UT
			above the NW Limb extending from the W up to past the 
			N Pole. It is shown as a bright loop front surrounded 
			by a fainter and diffuse envelope (shock?). By 23:42 
			UT, the C3 occulting disk is completely covered. By 
			01:42 UT (on next day), the LE on NW already crossed 
			the outer edge of the C3 FOV. The mean plane-of-sky 
			speed of the LE (outermost front of the diffuse 
			envelope ahead of the loop-like feature) at PA 329 
			was ~2890 km/sec (as measured on C3 in only 2 frames, 
			as it is two difficult to discern the feature tracked 
			in the following frame, if not already out of the 
			FOV). For the sake of completeness, the mean plane-of-
			sky speed of the LE of the loop-like feature at PA 329
			was ~2400 km/sec (based on C3 data, only 3 frames).
			GOES reported an X2.6 X-ray flare during a long 
			duration X-ray event on NOAA AR 10720 (N15W05) between
			22:25 - 23:31 UT with peak emission at 23:02 UT (on
			2005/01/15), most likely associated to the signatures 
			observed on C2/C3. EIT 195 images show a strong
			brightening on the aforementioned AR starting at ~ 
			22:36 UT, peaking by 23:12 UT (there is a small EIT 
			data gap between 22:36 UT - 23:12 UT due to the C3
			Polarization sequence taken during that time). FC to 
			NW of the AR is blown away during the gap. In summary,
			the event has therefore been determined as an asymmetric
			'full' halo event, frontsided. 
	  

2005/01/16 (Sunday)

	Data degraded since early in the day by snowstorm (proton event).
	Degradation becomes more mportant by the end of the day.

00:06 UT  E Limb	Faint system of wide loop fronts developing slightly
			toward ESE in the aftermath of previous halo.

05:30 UT  N East	Brightening along streamer preceding an elongated 
			and expanding loop-like structure.

16:54 UT  N West	Expanding 'curved' feature develops being 'pushed'
			toward N. It fades throughout C3.
  

2005/01/17 (Monday)

09:30 UT  N West	Very bright loop front on the NW quadrant surrounded 
	  (HALO)	by a very tenuous and diffuse excess intensity, which 
			in fact, can be guessed (though barely) in previous 
			frame at 09:06 UT. By 09:54 UT, the LE on NW already 
			exited the C2 FOV, the occulting disk being completely
			covered. Please note that at that time, a new bright 
			and ragged front appears above the NW Limb. The 
			snowstorm associated with the proton event reported 
			to start on previous day is still present on the C2/C3
			images, becoming progressively more important (by 
			around 12:30 UT) until making the C2 images completely
			degraded by 14:07 UT (14:19 UT for C3). 
			The event is first seen in C3 at 09:42 UT above the 
			NW Limb. It is shown as a bright loop front surrounded 
			by a fainter and diffuse envelope (shock?). The 
			next frame at 10:20 UT shows i) the diffuse envelope, 
			ii) the loop front, and iii) a much brighter ragged
			front, most likely the C3 counterpart of the front
			appearing in C2 at 09:54 UT. The C3 occulting disk is
			completely covered by that time, i.e., at 10:20 UT. 
			The outermost LE of the 'complex' event  reaches the 
			end of the C3 FOV by 11:42 UT. The mean plane-of-sky
			speed of the LE of the outermost front of the diffuse
			envelope [i.e., feature described as i)] at PA 326 was
			about 2185 km/sec (as measured on C3 in only 4 frames).
			On the other hand, the mean plane-of-sky speed of the
			apparently fastest outermost feature belonging to the
			bright loop [i.e., feature described as iii)] at PA 263
			was 2350 km/sec (based on C3 data, only 4 frames). 
			Given the superposition of structures during the
			development of the complex event, it is difficult to 
			give a reliable value for the speed of the feature
			described as ii).
			GOES reported a long X-ray duration event on NOAA AR
			10720: an X3.8 X-ray flare (N15W25) between 06:59 - 
			10:07 UT with peak emission at 09:52 UT, associated 
			to the signatures observed on C2/C3; just after a 
			compact C3.9 X-ray flare (N15W21) between 06:06 - 
			06:15 UT with peak emission at 06:10 UT. EIT 195 images
			show a steady increase in intensity on the AR 10720 
			since around 07:48 UT, peaking at 09:48 UT. Inspection 
			of running differences show an 'intensity peak' at 
			08:00 UT followed by expanding loop-like structures
 			toward NW. By 09:36 UT the loops on NW of the AR open 
			and then disappear followed by a wave to NNE, N, and 
			NW of the AR. Another CME signature can be seen after
			09:48 UT (time of the strongest brightening): wave to
			NNE, NW, W, SW, and SSW on disk plus NW, W, SW, SSW
			off-limb. In summary, the event has therefore been
			determined as an asymmetric and complex 'full' halo
			event, frontsided. 


	NOTE: 	Please note that GOES recorded previously two M2-class flares
		(peak emissions on 2005/01/16 @ 22:03 UT and on 2005/01/17 @
		03:21 UT). No clear signatures of associated CME can be seen 
		in LASCO data.

	LASCO Data strongly degraded after proton event.

2005/01/18 (Tuesday)

	LASCO Data still strongly degraded (snowstorm) by proton event on
	previous day associated to the X3.8 X-ray flare and Complex Full Halo
	event (last C2 image at the time of writing: 12:55 UT).