* 2005/05/28 - 2005/06/05: LASCO Extra PBs for 3D CME Study. No EIT CME Watch during this period (only synoptic). * 2005/05/27: EIT CME watch in 304 between 00:00 - 24:00 UT. * 2005/05/26: EIT CME watch in 304 between 13:34 - 24:00 UT. * Medoc Campaign started on May 16. Since then SOHO is in Telemetry submode 5 (until June 3 afternoon UT). EIT 195 CME watch at half resolution (512x512).
N West Very slow development of a system of faint loops that started to be seen by the end of previous day. Some small and faint blob-like fronts superposed in the LOS (moving faster). 13:27 UT S West Diffuse loop front that initially shows up as a fan- like front. 15:06 UT S West LASCO/EIT observed a full halo event. The event was (HALO) first clearly seen in C2 at 15:06 UT all above the SW Limb and S Pole. However, a thin brightening just above southern edge of the occulting disk can already be guessed in previous frame (i.e., at 14:50 UT). The event develops in the C2 FOV as a bright, wide, and expanding loop front. It superposes in the LOS with the trailing part of a prior (relative narrow) event developing on SW (which first appeared in C2 by 13:27 UT). During its evolution in C2, very faint circular extensions can be discerned covering the occulting disk. Our main event is first seen in C3 just appearing above the SW Limb at 15:42 UT. By 16:18 UT, faint and diffuse circular extensions surround the occulting disk. The plane-of-sky projection of the bulk of the CME develops toward SW. The mean plane-of-sky speed of the event at PA 235 was ~ 575 km/sec, showing a slight deceleration (based on C2 and C3 data; last C3 frame at 17:18 UT, LE at ~ 9.5 solar radii). GOES reported several B-class X-ray flares on NOAA AR 10767 during the day. In particular, a B7.5 X-ray flare (on ~ S09E15) between 13:10 - 15:08 UT with peak emission at 14:20 UT (LDE) is most likely associated with the event recorded by LASCO. EIT 195 running difference images show by 12:36 UT a very faint signature of an apparently backsided CME above the SW Limb (EIT 195 counterpart of the event first seen in C2 at 13:27 UT, not associated with our main event). The EIT 195 CME watch was interrupted then at 12:48 UT to start the CME watch in 304 A (JOP 124: Eruptive Filament in Active Region). EIT 304 images show the eruption of a backsided prominence already above the SW limb at 13:19 UT (EIT 304 counterpart of C2 event at 13:27 UT). Top of post-event arcades visible by 13:36 UT. By 13:48 UT, signatures of our main event start to be visible. In particular, material ejected toward SW from nearby AR 10767. In addition, more material (1) shows up above the SW Limb (a little bit to S of the barely backside prominence ejection). Inspection of the 304 movie seems to indicate that the latter (1) could be related to the ejection from nearby AR 10767. In summary, the event has therefore been determined as a Full Halo Event, frontsided, associated with a LDE B-class X-ray flare from AR 10767 and (apparently) filament ejection. 21:26 UT E Limb Initially faint loop front develops as a wide loop front with faint extensions spanning up to the S Pole. By 22:26 UT, a very faint and diffuse front can be discerned on ENE, moving apparently faster than the loop just mentioned above (it looks like extremely faint circular extensions cover the occulting disk, giving the appearance of a very faint full halo event). This front on ENE is followed at 23:26 UT, by a faint and ragged loop front. Also by 23:26 UT starts to be discernible, above the N Pole, a faint and diffuse loop front. It is difficult to establish the association (if any) between the different features observed. They all fade throughout C3. GOES recorded a C8.6 X-ray flare from NOAA AR 10767 (S08E11) between 20:57 - 22:04 UT with peak emission at 21:39 UT. EIT 304 running difference images show a couple of brightenings on AR 10767 (at 21:13 and 21:36 UT).
00:50 UT SS West Expanding loop front. Note that by 23:50 UT on previous day a thin brightening can already be guessed. It is followed at 02:26 UT by a narrower front moving apparently faster. The event partly superposes in the LOS with some small ragged fronts and gusty outflow under development on WSW. 06:26 UT ES East Ragged loop front followed at 07:26, 08:26, 09:50, and 11:26 UT by similar (though narrrower) fronts. 08:06 UT N West A ragged front develops behind the faint system of loops under development since early on previous day. 08:50 UT S West Asymetric (spray-like) loop front. Difficult to give an exact time of first appearance. Time of the last C2 image analyzed: 12:06 UT.