LASCO Activity Report for
July 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

2005/07/20 (Wednesday)

	
08:54 UT  W Limb	Faint, (initially) loop-like front that quickly fades.

08:54 UT  EN East	Initially bright front develops as an asymmetric loop
			front.

	15:00 - 17:00 UT	No LASCO C2 images. 
				High cadence C3 PBs images for the Faraday
				Rotation Study with Cassini Campaign.

17:07 UT  N Pole	Faint and diffuse front followed at 18:30 UT by another
			one on NNE.

21:30 UT  N Pole	A faint and diffuse wide loop front develops, moving 
			apparently faster than previous event.

2005/07/21 (Thursday)

	
03:54 UT  Halo		The event was first seen in C2 at 03:54 UT as a very
			bright loop-like front spanning all above the NW, N 
			Pole, NE, and E Limb. Faint and diffuse extensions can 
			be seen all around the C2 occulting disk, though they 
			are extremely faint above the S Pole. The main loop 
			front develops in the C2 FOV toward N with its legs
			apparently anchored on the W and ESE limbs. The event 
			is first seen in C3 at 04:18 UT, very bright on NE,
 			with faint and diffuse circular extensions already
			surrounding completely the C3 occulting disk. The mean-
			plane-of-sky speed for different features of the event 
			at several position angles is given below (based on C3
			data):
			- LE of the diffuse front at:
			PA 000: 1484 km/sec
			PA 035: 1471 km/sec
			PA 180: 1230 km/sec (LE rather faint and diffuse)
			PA 275: 1160 km/sec (LE rather faint and diffuse)
			- LE of the bright loop front developing mainly 
			toward NE, at PA 040: 1160 km/sec
			showing practically no acceleration (in all cases).
			GOES reported extremely low X-ray activity during the 
			day (A-class). The disk of the Sun is spotless. 
			Likewise, EIT 195 images do not show any significant
			activity on the disk. Only likely signature of the 
			event is an extremely faint intensity disturbance that
			seems to propagate all above the limb in the northern
			hemisphere starting at around 03:24 UT. In summary, 
			the event has therefore been classified as a strong 
			full halo event, backsided. 

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