CME, Flare and Particle Event
Click on the images for larger/full field versions. |
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LASCO C3 image of the CME which is heading for earth. |
EIT 195 Å image of the post-CME loops associated with the
flare |
Caption: Solar activity picked up on 24 September 2001, with a large coronal mass ejection starting at 09:36 UT, an X2.6 X-ray flare (peaking at 10:38 UT), and a solar energetic particle event that started at about 12UT was still going strong 30 hours later.
Particle events show up as "snow" in the real-time images from LASCO and EIT, and can also be seen as a "byproduct" by the CELIAS/MTOF Proton Monitor "flare monitor" page (see links below).
The particles affect other instruments as well, and the Coronal Diagnostic Spectrometer (CDS) ramped down their dectector high voltages on Monday, to minimize instrument degradation (with these levels of particle radiation, their observations are next to useless). Another instrument, the Ultraviolet Coronagraph Spectrometer (UVCS) was monitoring the situation closely.
The shock front arrived at SOHO around 19:50 UT on 25 September, along with an even larger flux of high-energy particles. This caused an instrument anomaly for one of the particle instruments (COSTEP - Comprehensive Suprathermal and Energetic Particle Analyzer). Another instrument (UVCS - Ultraviolet Coronagraph Spectrometer) chose to safe their instrument to reduce wear on their detector.
The shock was clearly visible in the data from the CELIAS/MTOF Proton Monitor on their "shockspotter" page - although the automatic shockspotter algorithm didn't flag this event due to the geometry of this particular event (it was detected, but not at a high enough confidence level to warrant a flag).
Related links:
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Instruments: |
LASCO (Large Angle and Spectrometric Coronagraph); |
Taken: | 24 September 2001 |
Picture credits: |
SOHO/LASCO and SOHO/EIT (ESA & NASA) |
