Sunspot group AR11339 (AR stands for Active Region) has just rotated onto the Earth facing disk of the Sun. Before coming completely into view the region had produced two M flares in 24 hours (an M4.3 flare on 2-Nov-2011 at 21:52 UT and an M2.5 flare on 3-Nov-2011 at 10:58 UT). Here is another look at AR11339. This video is from the Solar Optical Telescope (SOT) onboard the Hinode spacecraft. (credit:Dr. Tom Berger)
The shape and complexity of an active region’s visible sunspots and magnetic field are the main indicators of its potential activity. These features are hard to see until a region has rotated fully into view but indications were that it had the potential of producing many C flares, a few M and maybe even an X flare. AR11339 has not disappointed! At 20:27 UT, November 3, 2011 it produced an X1.9 solar flare, 20 minutes before the drafting of this post.
This figure shows the GOES X-ray emission over the past 6 hours and 3 days. At the end of each graph the X-rays rise to X1.9 then start to decrease.
It is too early to look at SDO images from the event. We will have to wait and see if this flare had an associated CME (coronal mass ejection) as well as wait to see what else AR11339 might have in store for us.