Solar Influences Data Center (SIDC) / RWC Belgium Royal Observatory of Belgium E-mail: Pierre.Cugnon@oma.be http://sidc.oma.be SIDC WEEKLY BULLETIN -------------------- WEEK 108 from 2003 Jan 20 SOLAR ACTIVITY -------------- Several active regions produced M class flares during the week. NOAA AR 0269, Catania number 30, just appearing at the eastern limb, produced an M1.9 flare on January 21. M1.2 flare was produced by the NOAA AR 0260 (Catania number 20) on January 22. NOAA AR 0266, Catania number 25, produced three M-flares (M1.0 and M2.5 on January 23, M1.9 on January 24). Then situation became more quiet as just several C-flares happened at the end of the week in NOAA ARs 0266 and 0268, Catania numbers 25 and 29 respectfully. Several CMEs were associated with these flares, but they did not seem to be directed to the Earth. The only exception is perhaps the partial halo CME first registered by SOHO/LASCO at 04:54 UT on January 24. It was associated with the M1.9 flare in NOAA AR 0266, Catania number 25, which at this time was situated close to the central meridian. This partial halo CME was, however, very faint and slow (the mean plane-of-sky speed for this event was 283 km/s). Two large coronal holes were dominant solar structures all the week and determined the geomagnetic situation. One of them was the southern polar coronal hole with low-latitude extensions; another one - a transequatorial coronal hole. At the end of the week these coronal holes have rotated out from the central meridian. GEOMAGNETIC ACTIVITY -------------------- During the whole week the geomagentic conditions were disturbed reflecting the Earth position inside fast flows from two large coronal holes (see above). Kp index reached 5 in the morning of January 20 when the Earth has entered the flow from the southern polar coronal hole. Late on January 22 Kp index reached 5 again as the Earth entered the interaction region between two fast flows from these coronal holes. Then Kp index was often rising to 4 (up to 5 on January 25) responding to the fast solar wind periods with predominantly negative north - south interplanetary magnetic field component Bz. Energetic protons flux was low during the whole week. --------------------------------------------------------------------------- DAILY INDICES DATE RC 10CM Ak BKG M X 2003 Jan 20 161 138 018 B4.2 0 0 2003 Jan 21 146 134 021 B5.4 1 0 2003 Jan 22 135 130 021 B3.4 1 0 2003 Jan 23 104 136 017 B4.2 2 0 2003 Jan 24 121 130 022 B4.4 1 0 2003 Jan 25 /// 129 025 B3.2 0 0 2003 Jan 26 /// 125 022 B2.6 0 0 # RC : Sunspot index from Catania Observatory (Italy) # 10cm: 10.7 cm radioflux (DRAO, Canada) # Ak : Ak Index Wingst (Germany) # BKG : Background GOES X-ray level (NOAA, USA) # M,X : Number of X-ray flares in M and X class, see below (NOAA, USA) --------------------------------------------------------------------------- NOTICEABLE EVENTS DAY BEGIN MAX END LOC XRAY OP 10CM TYPE Cat NOAA NOTE 21 1459 1526 1552 S07E90 M1.9 380 30 0269 EIT derived location 22 0435 0444 0450 N15W05 M1.2 1F 20 0260 23 0442 0448 0456 M1.0 25 0266 23 1228 1243 1249 S22E17 M2.5 1N 76 II/2 25 0266 24 0312 0327 0340 S22E10 M1.9 1N 97 II/3,III/2 25 0266