LASCO Activity Report for
July 27, 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

2005/07/26 (Tuesday)

03:54 UT  EN East	Jet-like front.

04:54 UT  EN East	Very bright and wide ragged loop front. Faint and 
			diffuse extensions to N and S. As it happened with
			previous event, faint extensions can be seen past the 
			N Pole up to the W Limb by 05:30 UT. An extremely
			weak signal can be seen on SW by 06:30 UT. Signatures
			of the event in the western hemisphere are practically
			non-discernible in C3.  The mean plane-of sky speed of
			the ragged LE at ~ PA 85 was ~ 1290 km/sec, showing
			practically no acceleration. Again, EIT 195 images do 
			not show significant activity on the disk by the time 
			of the event. But it does show a backsided CME above
			the ENE limb starting by 04:24 UT. 

09:30 UT  E Limb	Bright loop front just appearing develops as a very
			bright ragged and wide loop front with faint and diffuse
			extensions to N and S. By 09:54 UT, the LE on E is
			already past the outer edge of the C2 FOV. The brightest
			structure develops toward ESE. The event is first seen 
			in C3 at 09:42 UT, just appearing above the E Limb. 
			By 10:19 UT, faint extension surround the main structure,
			on S well past the S Pole. The angular extent of the
			event at 11:42 UT is about 230 deg (from PA 005 - 235),
			extremely faint on SW. Note that the last C3 image where
			the event can be seen is at 14:18 UT (there is afterward
			a gap between 15:00 - 17:00 UT due to the especial PBs
			images for the Faraday Rotation Study still under way).
			The mean plane-of-sky speed of the ragged LE at PA 082
			was ~1800 km/sec (based on only the first 3 C3 frames
			were the event is seen, as the LE becomes then too faint
			and diffuse for accurate measurements). EIT 195 images 
			do not show significant activity on the disk that could
		 	be related to the event by the time of the event.
			However, it does show signatures of an important (and
			still backsided) CME above the E Limb, first clearly 
			seen at 09:24 UT. In summary, the event has therefore
			been classified as at least a Partial Halo event,
			backsided.

	15:00 - 17:00 UT	No LASCO C2/C3 CME watch images.
				High Cadence C3 PBs subfield images for the
				Faraday Rotation Study with Cassini Campaign.

17:06 UT  E Limb	Asymmetric loop front already under way after gap.

17:06 UT  WN West	Big twisted structure already under way after gap (LE
			past the outer edge of the C2 FOV).

23:30 UT  EN East	In the gusty outflow, a small ragged front becomes
			discernible.

2005/07/27 (Wednesday)

01:31 UT  WN West	Bright and elongated ragged loop front. EIT 195 images
			show signatures of a backsided CME above the ENE limb 
			(developing toward NW) starting at 01:13 UT.

04:54 UT  E Limb	Bright loop front. Faint and diffuse extensions to N 
			and S can be seen by 05:08 UT. By 06:06 UT, the C2
			occulting disk appears fully covered (by that time, 
			the LE on E is already well past the outer edge of C2).
			Prominence material follows the outer front on ENE. 
			Note that by 07:54 UT, a new bright loop-like front
			follows behind the trail of the prominence. The event 
			is first seen in C3 at 05:18 UT as a very bright loop
			front on E, with faint and diffuse extensions to N and 
			S. By 06:18 UT, the C3 occulting disk seems to be fully
			surrounded by these faint extensions (though they are
			very faint on the western hemisphere). The diffuse
			structures on west that made the C2 occulting disk to
			appear covered by 06:06 UT, are first seen in C3 by 
			07:42 UT on W and SW. The mean plane-of-sky speed of 
			the LE of the outermost front at PA ~ 83 was ~ 1960
			km/sec, showing practically no acceleration (based on 
			C3 data). GOES reported an M3.7 X-ray flare on N11E90
			between 04:33 - 05:30 UT with peak emission at 05:02 UT.
 			The source region is still behind the limb and is
			apparently located in the position of the old NOAA AR
			10786. EIT 195 images show the slow and gradual increase
			of a system of loops barely anchored behind the limb
			starting at around 03:48 UT, with a sudden brightening
			increase at 04:36 UT, just on the ENE limb. By 04:48 UT,
			the images show release of prominence material, jointly
			with a strong intensity disturbance all above the 
			eastern limb. A slight intensity disturbance can be 
			seen on the eastern part of the disk afterward. Post-
			plare loops can also be seen developing just above
			the limb. By 07:13 UT, another CME signature develops
			above the ENE Limb (also barely backsided). In summary,
			the event has therefore been determined as a strong
			limb event (barely backsided), with an associated 
			shock that made the event to look like an asymmetric 
			full halo event. The event was associated with an M3.7
			X-ray flare on the apparently old location of the former
			NOAA AR 10786 (barely behind the ENE limb). The location
			of this active region makes the arrival of a CME-
			produced interplanetary disturbance to the Earth
			unlikely.

07:54 UT  EN East	In the trailing material of previous event, a new bright
			and ragged loop-like front can be seen. EIT 195 images
			show by 07:13 UT a CME signature developing above the 
			ENE Limb (barely backsided).

11:06 UT  EN East	Small and bright ragged front in the southern part of 
			the trailing material of previous event. GOES reported
			a C1.7 X-ray flare on N14E88 between 10:31 - 11:30 UT
			with peak emission at 10:55 UT.

Time of the last C2 image under analyis: 12:30 UT.