Subject: Partial Halo Event on 2008/04/26, frontsided

UCMEO 93001 80428 1450/
80426 61430 80318 0001/ 360// 113// 30475
80426 61354 81438 10908 ///// 1112/
99999

PLAIN


LASCO/EIT observed an at least Partial Halo Event on 2008/04/26. The event
was first seen in C2 as a diffuse brightening above the ENE Limb at 14:30
UT. It develops as an expanding ragged loop front immediately followed by
another expanding and bright ragged front. The event covers practically
the whole northern hemisphere in the C2 FOV. A faint expanding loop front
can be seen by the time on SE. The event is first seen in C3 above the NE
Limb at 15:42 UT exhibiting a double front LE. The plane-of-sky speed of
the outermost front at PA 42 is ~ 375 km/sec, while for the second front
is ~ 475 km/sec at PA 75 (determination based on C3 data, both cases).
The HT profiles show practically no acceleration. The outermost front
fades before reaching the end of the C3 FOV.

EIT 195 images show the ejection of a small piece of faint material toward
W starting at ~ 12:36 UT from nearby an AR located around N08E09, followed
by a tiny and gradual expansion of loops. By 14:00 UT, a dimming region
develops toward E jointly with a rather circular wave with epicenter on
the AR. Post-flare loops after 14:00 UT. GOES observed a B3.8 X-ray flare
on N08E09  between 13:54 - 14:38 UT with peak emission at 14:08 UT.

The event has therefore been determined as an at least Partial Halo Event,
frontsided, most likely associated with a prominence eruption and B-class
X-ray flare.

Images and movies of the event will be shortly made available at:

http://umbra.nascom.nasa.gov/lasco/observations/halo/2008/080426/

Best regards

Guillermo Stenborg

..............
BT