LASCO Activity Report for
July 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

2005/07/15 (Friday)

00:54 UT  ES East	Faint jet-like front preceding an elongated loop-like 
			front at 02:30 UT. The loop front fades throughout C3.

02:30 UT  W Limb	Bright loop front developing slightly toward WSW. Much
			gusty outflow continues all above the W Limb.

08:30 UT  ES East	Very diffuse and elongated loop-like front.

09:06 UT  WN West	Diffuse brightening just appearing, develops as a
			not-well-defined front. It is followed at 09:54 by a
			ragged loop front developing toward W.

11:54 UT  WN West	Bright and ragged loop front developing as a nice
			balloon-type CME (with twisted inner structure).
			Gusty outflow continues.

16:06 UT  W Limb	Elongated and bright front developing slightly toward 
			WSW. Gusty outflow continues.

20:06 UT  WN West	Faint front just appearing. It develops as a bright 
			loop front, followed (at 20:54 UT) by a wider and 
			bright loop front which in turn is followed by a bright 
			inner structure. By 22:30 UT, faint extensions
			(apparently deflected structures) can be seen above the 
			S Pole. The event is seen in C3 at 21:18 UT above the 
			WNW Limb with faint extensions developing then above
			the S Pole (they do not seem to surround the occulter).
			EIT 195 images show, starting at around 19:13 UT, the
			slow expansion of a system of loops on WNW (apparently
			anchored barely behind the limb on NOAA AR 10786). By 
			20:48 UT, the expansion accelerates. GOES reported a 
			long duration C6.5 X-ray flare above NOAA AR 10786
			(almost behind the limb) starting at 20:08 UT (Source:
			BBSO Active Region Monitor). In brief, the event is
			clearly a limb event. Its associated shock gives the
			appearance to the event of, at least, a faint partial
			halo.

2005/07/16 (Saturday)

00:06 UT  W Limb	Small front develops as a relatively bright and ragged
			loop front slightly toward WSW. Gusty outflow continues.
			EIT show a strong CME signature with source region 
			nearby AR 10790 by the end of previous day.

01:32 UT  EN East	Slow development of a faint system of loops along 
			streamer. Pseudo-continues outflow superposed in the 
			LOS.

13:54 UT  WN West	Initially bright ragged front that quickly fades in
			the gusty outflow.

19:31 UT  E Limb	Extremely faint front starts to be discernible above 
			the E Limb in C2 (though it is difficult to precise the
			exact time) partly superpose with the pre-existent
			development of a faint system of loops on ENE. Our front
			develops then in C2 as a very faint (and slow) full halo
			CME (though extremely faint on W). It is first seen in 
			C3 just appearing above the E Limb at 23:18 UT (the 
			part of the event on W, if any, is not discernible in
			C3). By 06:42 UT, the event is already barely discernible
			(the LE on W just by 11.5 solar radii). No clear
			signatures of any frontsided event can be seen on EIT 
			195 images by the time.

2005/07/17 (Sunday)

00:06 UT  S East	Slow development of a faint system of wide and 
			expanding loops. Difficult to give an exact time of
			first appearance.

00:54 UT  W Limb	Fan-like front immediately followed a little bit to N
			by a diffuse and elongated loop-like front. They fade
			throughout C3.

04:06 UT  W Limb	Ragged loop front that fades throughout C3.

07:32 UT  W Limb	Bright and narrow front followed at 09:54 UT by a 
			bright and ragged front. By 10:34 UT, an initially
			bright ragged loop front follows, developing slightly
			toward WNW. The three fronts are then quickly surpassed
			by the following halo event.

11:30 UT  N west	Very strong loop-like front partly superposed with
			previous event (see entry at 07:32 UT). By 11:54 UT,
			faint loop-like extensions can be seen all above the 
			S Pole, the C2 occulting disk being completely covered 
			by 12:06 UT. By that time, the LE of the event on W is
			already past the outer edge of the C2 FOV, while the 
			halo extensions on E are just above the limb. Much 
			gusty outflow then on the W-WNW Limb. The event is 
			first seen in C3 at 12:18 UT, as a very bright loop 
			front on NW surrounded by faint and diffuse extensions
			that almost cover completely the C3 occulting disk
			(which is then fully surrounded by 12:42 UT). The mean
			plane-of-sky speed of the LE of the event (outermost
			front) at several PA is given below (based on C3 data):
			. PA 049: 1060 km/sec
			. PA 232: 1340 km/sec
			. PA 304: 1453 km/sec
			. PA 350: 1364 km/sec
			showing practically no acceleration (in all four cases).
			GOES reported multiple B-class activity during the day 
			on NOAA ARs 10790 (in average at S10W90) and 10789 (in
			average at N13W90) plus an impulsive C4.3 X-ray flare 
			on AR 10790 (S10W90) that peaked at 06:29 UT. They do 
			not seem to be directly associated with the big halo
			under analysis, as observed in the EIT 195 images. EIT
			195 running difference images show signatures of a big
			CME with source region behind the limb (most likely
			nearby the actual location behind the disk of the 
			already gone 10786). It starts to be clearly seen by
			10:50 UT as the expansion of a loop front above the WNW
			limb, which seems to break up by 11:36 UT. A big
			intensity disturbance to N and S above the limb (as 
			well as partly on the most western part of the disk) 
			can be seen afterward. In summary, the event has
			therefore been classified as a strong and asymmetric 
			full halo event, backsided. Note that after ~14:00 UT,
			a slight and gradual increase of energetic particles
			hitting the CCD can be seen in C2 images.

13:54 UT  W Limb	In the aftermath of the Halo CME, the slow development
			of a faint system of loops can be seen. Difficult to
			give an exact time of first appearance.

2005/07/18 (Monday)

	  Much gusty outflow on ENE and ESE since late on previous day.

00:30 UT  WN West  	Faint loop front in the gusty outflow.	

Time of the last C2 image under analysis: 12:06 UT.