Ten sunspot groups were reported by Catania today. The Catania sunspot group 17 (NOAA AR 1959) developed the beta-gamma configuration of its photospheric magnetic field and produced four C-class flares yesterday. The strongest flare of the past 24 hours was the C3.6 flare peaking at 22:49 UT
on January 20 in the Catania sunspot group 20 (no NOAA number yet). We expect flaring activity on the C-level from these two groups, with an M-class flare possible but not very likely.
The above-mentioned C3.6 flare was accompanied by a halo CME first visible in the SOHO/LASCO C2
field of view at 22:12 UT. The bulk of the CME erupted toward the east, but there were weak extensions to form a full halo. The projected plane-of-the-sky speed of the CME was around 1000 km/s (with a big
uncertainty due to a not well-formed front). SDO/AIA data show that the CME was associated with coronal dimmings and a post-eruption arcade. Only the CME-driven shock may arrive at the Earth on January 24, although it is unlikely. In case of the shock arrival, the geomagnetic conditions are not
expected to go above active (K = 4). Another halo CME (this time a partial one) was first observed in the SOHO/LASCO C2 field of view at 15:24 UT on January 20. The CME had the angular width of around 230 degrees and the speed around 550 km/s. STEREO/EUVI B data show that the CME was associated with a far side eruption (as seen from the Earth) with the source region located around S15E170. This CME will therefore not arrive at the Earth and have no geomagnetic consequences. The interplanetary
magnetic field (IMF) magnitude reached 10 nT in the past hours, indicating the arrival of the interaction region between the slow and the fast solar wind flows. The IMF Bz component is increased but fluctuating between positive and negative values. Currently the solar wind speed is still low (between 300 and 350 km/s), but the arrival of the fast flow from the low-latitude coronal hole in the northern hemisphere is still expected today. Active geomagnetic conditions will be possible.
Equipment: Coronado 90 + SBIG 8300s + LX75
Time UT: 19:00
Exposure 0.8 sec.
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