Over the last 24 hours, 2 M-class flares were produced by a currently unnumbered region at the northeast limb: an M2.1 flare peaking at 15:26UT, and an M1.4 flare peaking at 21:26UT. NOAA 2157 and 2158 produced 2 C-class flares each. The strongest was a C9.5 flare peaking at 02:24UT in NOAA
2157. Both of these regions have no longer a delta structure, but spots of opposite magnetic polarity are still close together. Based on the currently available imagery, no CMEs seem to have been associated to these flares. M-class flares are expected, with a chance on an X-class event.
On 11 September around 23:00UT, ACE observed a shock in the solar wind. Wind speed abruptly changed from about 350 to 480 km/s. Bz oscillated between -14 and +11nT. This was the arrival of the halo CME related to the M4-flare from 9 September. The impact resulted in active geomagnetic conditions (Dourbes), while Kp reached minor geomagnetic storm levels. Also the proton flux slightly increased. The arrival of the halo CME from the X1 flare is expected for later today. Pending the orientation of the CME’s magnetic field, this may result in a major geomagnetic storm, with locally severe geomagnetic storming possible.
Equipment: Coronado 90 + Imaging Source DMK + LX75
Processing: Photoshop, Avistack 300 frames
Time UT: 16:00
Exposure 1/500 sec.