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Just as solar scientists were ready to start breathing normally again, active region 10486 blasted off yet another mega-flare, starting at 19:29 UT on 4 November 2003. This one saturated the X-ray detectors on the NOAA's GOES satellites; the jury was therefore out for a while on the definitive classification of the flare. Based on the data found on the NOAA SEC's space weather pages (and links therein), speculations ranged from simply well above X20, to X40 or even X50!

A day later, word came from the SEC that their best estimate was X28, with a peak around 19:50 UT. Although the exact number will likely be debated for some time, it is now official: We have a new #1 X-ray flare for the record books.

Earlier flares from the same region are described on this Hot Shot page. Taken together with the breathtaking farewell of region 10486, the last two weeks will stand out for decades in the X-ray flare community.

Saturation of the GOES detectors also happened once earlier in SOHO's history, on 4 April 2001. That flare was reclassified as an X20.

A very preliminary estimate based on just 3 images of the associated CME came out at about 2300 km/second. Although part of the CME is directed towards Earth, we expect to receive only a glancing blow, since the source region is right on the limb of the Sun as seen from Earth.

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Credits: SOHO/EIT (ESA & NASA)

