Halo CME Mail Date: Tue, 20 Mar 2001 12:25 From: Gareth Lawrence Subject: Partial Halo CME on 2001/03/20 ------------------------------------------------------------------------ UCMEO 93001 10320 1700/ 10320 60326 91542 1801/ 020// 113// 40360 10320 60224 90324 34005 09380 1112/ 99999 PLAIN BT LASCO (and EIT) observed a partial halo CME on 2001/03/20. The event was first observed in C2 at 03:26 UT, as a bright loop front over the W limb. At 04:06 this bright front extended from about PA 240 to PA 310, with fainter extension S to PA180 and N to PA20 making a total span of about 200 deg. The westerly front first appeared in C3 at 04:18. The mean plane-of-sky speed of the leading edge through to about 25 Rs was about 360 km/s at PA 270 (W limb), though the leading edge was noticeably faster through C2 and with discernible deceleration. The CME appears to be associated with two seperate events occuring almost coincidentally. GOES observed an M1.1 X-ray flare in AR 9373 between 02:06 and 02:25 UT and this event was observed by EIT at 02:24, some time after its peak. EIT then observed a small flare (not listed by SEC) and CME plus wave and dimming in AR 9380, somewhat to the E of AR 9373, between 02:36 and 03:12 UT. It appears as though the bright portion of the front may be due to the earlier flare, and the fainter portion due to the later flare and CME. GOES observed a third, slightly later event, which was seen by EIT at 03:24, and some of the material seen ejected after the initial front may be due to this event. Images and movies of this event are available at: ftp://ares.nrl.navy.mil/pub/lasco/halo/20010320 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 | ++