Latest issue
:Issued: 2010 Apr 03 1250 UTC

roduct: documentation at
http://www.sidc.be/products/presto
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# FAST WARNING 'PRESTO' MESSAGE from the SIDC (RWC-Belgium) #
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A B7.4 flare peaking at 09:54 UT was detected today in the Catania
sunspot group 56 (NOAA AR 1059) located around S25W05. It was
accompanied by a post-eruption arcade, coronal dimmings, possibly an EIT
wave and a partial halo CME (angular width around 210 degrees). The CME
was first detected at 10:33 UT (by LASCO) and at 09:54 UT (by
SECCHI/COR2 on STEREO A). The CME was moving at a projected
plane-of-the-sky speed of around 250 km/s (according to the LASCO data).
Using some reasonable assumptions on the CME geometry, the true radial
CME speed can be estimated to be around 600 km/s. The arrival of the
corresponding ICME (possibly an interplanetary flux rope) at the Earth
is thus expected in the morning of April 6. The flux rope orientation as
inferred from the SOHO/EIT and SOHO/MDI data is ESW, although it may
change during propagation. STEREO A and B data indicate that the bulk of
the CME was propagating to the south of the ecliptic (according to the
COR2 data). If the flux rope will arrive at the Earth, we expect a
strong geomagnetic disturbance. Currently, the Earth is inside a slow
solar wind flow (460 km/s) with average (5 nT) interplanetary magnetic
field magnitude. Geomagnetic conditions are expected to remain quiet in
the coming hours.
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