Halo CME Mail Date: Wed, 22 May 2002 15:50 From: Gareth Lawrence Subject: Full Halo CME on 2002/05/22, frontsided ------------------------------------------------------------------------ UCMEO 93001 20522 2000/ 20522 60326 90742 0001/ 360// 223// 41496 20522 60300 90424 35619 ///// 2222/ 99999 PLAIN BT LASCO and EIT observed a full halo CME on 2002/05/22. The event was first observed in C2 at 03:26 UT as a faint loop front over the SE limb; by 04:06 UT the C2 occulting disk was surrounded by a thick bright front in the W extending over both poles and fainter extensions in the E. The front first appeared in C3 at 03:42 UT with full coverage of the C3 occultor by 04:18 UT. The plane of sky speed of the front was measured as 1496 km/s at PA 237 (SE) with very slight deceleration through the coronagraphs' fields of view. The CME was most probably associated with a large, bright, fast eruptive prominence that EIT observed between 03:00 - 04:24 UT, in the region of the disk centred on S19W56. GOES notes a disappearing filament between 03:18 - 05:00 UT and a C5.0 X-ray flare between 03:18 - 05:02 UT with peak emission at 03:54 UT, from S30W34. Neither an EIT wave nor a dimming were observed in association with this event. Images and movies of this event are available at: ftp://ares.nrl.navy.mil/pub/lasco/halo/20020522 and please note that two other large events have been deliberately included in the movies. The first is a CME seen in the NE from 2002/05/21 21:50 and is probably associated with a M1.5 X-ray flare in AR9960, N17E38. The second is a CME seen in the SW from 2002/05/21 23:50 and is probably associated with a C9.7 X-ray flare in AR9948, S25W64. Due to the extents of the CMEs and the positions of their apparent source regions there is reason to believe that either or both might have a small earth-directed component; however both are likely to be overtaken by this third event, which is the fastest of the three. The full halo CME and be seen running into the later partial halo CME in the outer region of the C3 field of view, and the first partial halo CME is significantly slower. We therefore consider that a single complex ejecta at 1AU is the most likely outcome of these three events. For reference the speeds of the two partial halo CMEs average to 863 km/s and 1333 km/s . Best wishes, Gareth Lawrence. ++ | Gareth Lawrence, E-mail:grl@kreutz.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 | ++