Halo CME Mail Date: Wed, 19 Sep 2001 16:33 From: Gareth Lawrence Subject: Partial Halo CME on 2001/09/18, most probably frontsided ------------------------------------------------------------------------ UCMEO 93001 10919 2130/ 10918 61654 92342 2901/ 160// 213// 30332 10918 61524 91548 14915 09620 1212/ 99999 PLAIN BT LASCO and EIT observed a partial halo CME on 2001/09/18. The event was first observed in C2 at 16:54 UT as a narrow bright loop front in the NE. By 19:30 UT this front spanned some 230 deg over the N Pole from PA 290 to PA 160. The front first appeared in C3 at 19:42 UT with maximal coverage of the C3 occultor by 20:18 UT. The plane of sky speed of the front was measured as 332 km/s at PA 30 (NE) with significant acceleration through both coronagraphs' fields of view. Note that only C3 data out to ~15 Rs was used to obtain this estimate as a subsequent event made it difficult to identify the same feature beyond this The CME was most probably associated with an M1.3 X-ray flare in AR9620 between 15:31 and 15:43 UT with peak emission at 15:48. EIT also observed this flare between 15:24 and 15:48, peaking at 15:36. SEC places the flare at N15E49 and the region dirctly to the N was significantly affected. A dimming was observed in association with this event, but no wave. The timing of the flare is consistent with the slow plane-of-sky speed of the CME, especially early on in C2. Images and movies of this event are available at: ftp://ares.nrl.navy.mil/pub/lasco/halo/20010918a and one of the C3 movies shows the interaction with the subsequent event. 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 | ++