SOHO Breaking News: Big Bang from a Very Productive Region (January 20, 2005)

http://sohowww.nascom.nasa.gov/

SOHO Breaking News

Just in: The shock driven by the CME arrived at Earth around 17 UT on
January 21, causing a severe geomagnetic storm (Kp = 8). Norway already
reported beautiful aurora.

Active region NOAA 10720 has turned out to be one of the most flaring
regions of the last few years, with 15 M-class and 5 X-class events
since 14 January. The biggest flare so far came early on 20 January, an
X7.1 that peaked at 7UT (2am EST).

Even before the peak of the flare, energetic protons were pummeling SOHO
as well as other spacecraft. The particles show up as a "snow storm" in
the LASCO and EIT images as they crash into the detectors and deposit
part of their energy.

The SOHO spacecraft experienced minor glitches that could be fixed by
ground controllers, thanks to a clever software upgrade that was
performed in 1999. Without this upgrade, SOHO would have been thrown
into a spacecraft emergency due to the loss of its guide star. With the
improved software, several stars are tracked at the same time, and
losing the primary one is no big deal as long as there are more stars
left to track. During the first few hours of the storm, four stars were
lost.

Still, two of SOHO's instruments (CDS and UVCS) were manually put in
safe mode by turning down high voltages, to avoid negative effects of
the bombardement.

The energetic proton event was the 5th to hit the 'red zone' on the SOHO
CELIAS flare page. The total flux was a bit smaller than the previous
four and was decaying more rapidly. However, based on the flux level of
the highest energy protons ( 100 MeV), this radiation storm was the
strongest since October 1989, according to NOAA SEC. A rare, strong
ground-level event (GLE) was also observed. GLEs are increases in the
ground-level neutrons detected by neutron monitors and are generally
associated with very high energy protons (500 MeV). Elevated neutrons
at ground level means there are high fluxes of energetic protons near
Earth. High energy radiation storms can be particularly hazardous to
spacecraft, and to communication, navigation, and aviation operations at
high latitudes.

Scientists are still debating whether the energetic particles from such
events are accelerated by the flare itself, by the shock front of an
associated coronal mass ejection, or both.