Halo CME Mail Date: Fri, 6 Apr 2001 18:06:07 -0400 (EDT) From: Gareth Lawrence Subject: Full halo CME on 20010406 ------------------------------------------------------------------------ UCMEO 93001 10406 2300/ 10406 61930 92118 0001/ 360// 223// 41103 10406 61848 92024 23121 09415 1112/ 99999 PLAIN BT LASCO and EIT observed a full halo CME on 2001/04/06. The event was first observed in C2 at 19:30 UT as a bright wide front in the SE. The C2 occulting disk was surrounded by 19:54 although emission over the N pole was faint. The bright front first appeared in C3 at 19:42 with the C3 occultor surrounded by 20:18. The plane of sky speed of the fastest region of the front was measured as 1103 km/s at PA 120 (W) with no significant deceleration through both coronagraphs. Note that this speed was inferred fronm the limited data available at the time of writing The most probable source of the CME was an X5.6 X-ray flare in AR 9415, plus other associated activity. GOES records the flare between 19:10 and 19:31 UT with peak emission at 19:21. The flare was observed in EIT from 18:48 to 20:24 with peak emission at 19:24. An EIT wave was observed during the event, as was dimming. As with an ealier halo CME associated with an X-ray flare in AR 9415, a large CME was observed by EIT with the greater part of the ejection apparently originating rather nearer the limb. This is consistent with the bright front over the SE limb and fainter emissions elsewhere, but again the EIT data shows enough activity on the disk to suggest that the CME may have a significant Earth-directed component. Images and movies of this event are available at: ftp://ares.nrl.navy.mil/pub/lasco/halo/20010406 Best wishes, Gareth Lawrence. ++ | Gareth Lawrence, E-mail:grl@ajcannon.nascom.nasa.gov | | SOHO-LASCO Operations Scientist, | | CUA, Mail Code 682.3, | | NASA Goddard Space Flight Center, Phone: +1-301-286-2941 | | Building 26, Room G-1, +1-301-286-3447 | | Greenbelt, MD 20771. Fax: +1-301-286-0264 | ++