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Largest solar flare so far in Cycle 24

On August 9 at 08:05 UT, SWAP and LYRA onboard PROBA2 recorded a solar flare of class X6.9, the strongest so far in the current solar cycle. At the time of the flare, PROBA2 was offpointed to the west limb, close to where the flaring active region was located, so that part of the event could be observed off-limb.

X6.9 flare on August 9 2011 observed by SWAP X6.9 flare on August 9 2011, observed by LYRA

The flare was also associated with an enhanced proton flux, which was measured near Earth (see GOES data) and with 2 coronal mass ejections which were seen as type II radio burst by the radio station in Humain, Belgium. The strongest CME was later seen propagating in Earth direction (so-called ’halo CME’) in coronagraphs like SOHO/LASCO. Its average speed was measured as 1631.7 Km/sec.

The whole event was also observed in many different wavelengths, and high resolution, by SDO/AIA (see e.g. movie in 131A). But unfortunately blooming and diffraction highly affect the observations of the flaring site. As the CMOS detector of SWAP does not suffer from blooming, and thanks to its large FOV, SWAP and AIA data are complementary for the analysis of such strong flares.

The link to the enhanced SWAP movie is given here. More information on the space weather effects of this flare can be read in the news item on the SIDC website.

See online : Enhanced SWAP movie