LASCO Activity Report for
January 21, 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

2005/01/20 (Thursday)

00:06 UT  N East	Ragged front along streamer. Barely visible in C3.

03:30 UT  S West	Slow development of a system of loops along the s
			treamer.

04:06 UT  N West	Faint spray-like front.

	LASCO/EIT observed a major proton event most likely associated to
	an X7.9(GOES10)/7.1(GOES12) X-ray flare that started at 06:36 UT and 
	peaked at 07:01 UT. Signatures of a full halo CME can be guessed
	in the highly degraded LASCO data. Here comes the report:

06:54 UT  N west 	Extremely bright loop front above the WNW-NW limb. 
			An intense proton storm starts affecting by that time 
			the LASCO images. The next C2 frame (07:34 UT) shows 
			up 100 % contaminated and therefore practically 
			useless. The same occurs with the following frames 
			(at least up to the time of the last C2 frame at hand,
			i.e., 16:00 UT. The proton event is first seen in C3 
			at 07:54 UT, hiding any potential CME signatures that
			could be present. The next frame allows to guess a 
			ragged loop front all above the SE Limb. By 10:24 UT 
			the C3 occulting disk seems to be completely covered. 
			If, the LE is what I guess it is, the mean plane-of-
			sky speed of that front at PA 141 would be around 
			571 km/sec (based on C3 data). However, given the
			projected development of this guessed halo (apparently
			mainly toward SE), it is difficult to be sure about 
			its association with the X7 X-ray event. Maybe there 
			is a front already farther out on NW, but the 
			degradation of the data prevents telling anything.
			GOES(10) reported an X7.1 X-ray flare on NOAA AR 10720
			(N14W61) between 06:36 - 07:26 UT with peak emission 
			at 07:01 UT. EIT 195 images show between 06:36 - 
			06:48 UT a well-defined loop eruption toward NW above 
			the AR 10720, clearly under way before the X7 flare. 
			At 06:48 UT a strong brightening starts to be seen on 
			the aforementioned AR, peaking in the frame at 
			07:14 UT. Many particle hits by that time. Maximum
			particle counts occur by 07:27 UT. Given the data
			degradation due to the particle hits nothing can be 
			said about potential dimming/wave  associated to the
			event. It is difficult to be sure that the 'halo' 
			guessed in C3 is really a halo or if it is really
			associated with the big event. However, due to the
			location of the source region of the event on the 
			disk, is likely that the associated CME can at least 
			be partly directed toward Earth.

	LASCO Data strongly degraded after proton event, all along the day.
	Some small and/or faint events maybe missing.

09:31 UT  N East	Elongated loop front.

17:06 UT  N West	Very elongated loop front. Apparently, some faint 
			ragged fronts follow. GOES reported a C8.0 X-ray
			flare from NOAA AR 10720 (N19W64) between 16:08 - 
			16:19 UT with peak emission at 16:14 UT. EIT observes
			a compact event between 16:22 - 16:35 UT on NE of the 
			AR, possible wave to NNE, narrow CME off-limb. Couple 
			oc C-class flares follow (peak emission at 18:16 UT and
			21:53 UT).

2005/01/21 (Friday)

	LASCO Data still strongly degraded by proton event, though gradually
	subsiding. Some small and/or faint events maybe missing.

04:58 UT  WN West	Bright and elongated loop front. EIT 195 observes a
			compact brightening to NE of the AR 10720, eruption 
			of a compact loop, and opening of larger, off-limb
			structures between 04:31 - 05:26 UT. GOES reported a
			C6.3 X-ray flare from NOAA AR 10720 (N19W69) between
			04:17 - 04:34 UT with peak emission at 04:27 UT. 
			Couple of C1-class X-ray flares more peaking at 
			06:36 and  06:46 UT on AR 10720.

07:23 UT  S East	Elongated and very narrow diffuse loop-like structure
			that fades close to the inner edge of C3.

10:58 UT  WN West	Another bright and elongated loop front (narrower than
			the previous one).  GOES reported an M1.7 X-ray flare
			from NOAA AR 10720 (N19W81) between 10:10 - 10:19 UT 
			with peak emission at 10:16 UT.