Halo CME Mail

Date: Thu, 6 Apr 2000 19:01:23 +0000 (GMT)

From: Simon Plunkett

Subject: Halo CME on 2000/04/04

  ------------------------------------------------------------------------

LASCO and EIT observed a full halo event on 2000/04/04. This is presumably
the cause of the shock that was observed at ACE today. The CME was first
observed in a C2 frame at 16:32 UT, following a data gap of about ninety
minutes. The leading edge of the CME had already left the C2 field of view
at this time. Measurements in C3 indicate a plane-of-sky speed of 984 km/s
at PA 260 (W limb). The event was brightest and most structured over the
West limb, where a bright core was observed behind the leading edge. The
appearance was more diffuse and fainter in the east.

EIT observed a C9 flare in AR 8933 (N18 W58) at 15:24 UT, that was
probably associated with this flare. A large area of dimming between AR
8933 and AR 8935 (S07 W34) was also observed in EIT around the same time.

Images and movies of this event are available at the LASCO ftp server:

ftp://ares.nrl.navy.mil/pub/lasco/halo/20000404.

Apologies for the late delivery of this message. I was on travel earlier
this week and did not see the event until today.

Best wishes,

Simon Plunkett.

++
| Simon Plunkett,              E-mail: plunkett@kreutz.nascom.nasa.gov |
| USRA, 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       |
++