During the first half of September 2005, a period of increased solar activity occurred that rivaled the number and magnitude of flares produced during the “Halloween” storm in October-November of 2003.

The presence of NOAA active region 808 produced a total of 115 flares of GOES C-class or higher, including 26 M-class and 10 X-class flares (see Figure 1 below). The largest of the flares, a GOES X17.0 flare that occurred on September 7, 2005, was the largest flare that has occurred since the X28+ flare on November 4, 2003, and was just smaller than the X17.2 flare that occurred on October 28, 2003. This X17.0 flare was the 4th largest observed X-ray flare since GOES started making flare observations in 1986. Read more about the flares.

See the September 2005 newsletter.