:Issued: 2023 Sep 26 1342 UTC :Product: documentation at http://www.sidc.be/products/bul #--------------------------------------------------------------------# # SIDC Weekly bulletin on Solar and Geomagnetic activity # #--------------------------------------------------------------------# WEEK 1186 from 2023 Sep 18 Solar Active Regions (ARs) and flares --------------- There were 22 active regions visible throughout the week (NOAA ARs 3424 ro 3446). They all had relatively simple alpha or beta magnetic field configuration, except for NOAA AR 3435 (beta-delta), 3436 (beta-gamma), 3438 (beta-gamma), 3441 (beta-gamma), 3442 (beta-gamma), 3443 (beta-gamma) and 3445 (beta-delta). There were 10 M-class flares during the week, from NOAA AR 3435, 3443, 3436 and 3445. The strongest was an M8.7 from NOAA AR 3435, peaking at 12:54 UTC on 21 September. Coronal mass ejections --------------------- There were numerous CMEs per day during the week. In particular, five CMEs with a possible Earth directed component were observed on 17 September 13:25 UTC, 18 September 11:12 UTC, 20 September 14:10 UTC, 21 September 13:36 UTC and 22 September 02:24 UTC (all times referred to the first image of the CME visible in LASCO-C2). Coronal Holes --------------------- Several small coronal holes were visible during the week, but none of them were significant. Proton flux levels --------------------- the 10 MeV GOES proton flux was below the threshold throughout the week. Electron fluxes at GEO --------------------- The greater than 2 MeV electron flux was fluctuating above and below the 1000 pfu threshold, as measured by GOES 16. The 24 hour electron fluence was at moderate levels. Solar wind --------------------- The Solar wind conditions were dominated by the arrival of ICMEs. Two of them arrived on 18 September (the corresponding CMEs were from the previous week, on 14 and 16 September), preceded by a shock. The interplanetary magnetic field increased 22 nT then, with Bz down to -17nT and the solar wind speed reached 690 km/s (probably mixed with the influence of the high speed solar wind from small coronal holes). Then the conditions returned to slow solar wind, until 24 September when the shock and ICME corresponding to the CMEs of 21 and 22 September arrived to the Earth, causing the interplanetary magnetic field to increase to 33 nT and Bz down to -27nT, the solar wind speed reached 490 km/s. Geomagnetism --------------------- Geomagnetic conditions reached major storm levels globally (Kp 7) during the arrival of ICMEs on 19 September and minor storm levels locally (K_Bel 5). They were then mostly unsettled the rest of the week until the arrival of the shock and ICME on 24 September, when geomagnetic conditions reached moderate storm levels globally (Kp 6) and minor storm levels locally (K_Bel 5). --------------------------------------------------------------------------- DAILY INDICES DATE RC EISN 10CM Ak BKG M X 2023 Sep 18 170 130 155 031 C1.0 0 0 2023 Sep 19 189 164 166 040 C1.2 3 0 2023 Sep 20 /// 179 156 018 B9.4 1 0 2023 Sep 21 /// 198 168 012 C1.1 1 0 2023 Sep 22 239 215 176 010 C1.6 4 0 2023 Sep 23 /// 210 173 010 C1.2 1 0 2023 Sep 24 /// 189 174 021 C1.5 2 0 --------------------------------------------------------------------------- # RC : Sunspot index (Wolf Number) from Catania Observatory (Italy) # EISN : Estimated International Sunspot Number # 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 SUMMARY DAY BEGIN MAX END LOC XRAY OP 10CM Catania/NOAA RADIO_BURST_TYPES 19 0345 0355 0401 ////// M1.1 F 70/3435 II/2 19 0923 0938 0944 ////// M1.8 70/3435 19 2001 2014 2021 ////// M4.0 70/3435 20 1411 1419 1425 ////// M8.2 70/3435 21 1242 1254 1302 ////// M8.7 70/3435 22 0225 0336 0656 ////// M1.2 F 70/3435 22 1553 1623 1646 ////// M1.4 73/3443 22 1706 1715 1720 ////// M1.5 73/3443 III/2 22 2225 2300 2313 N02W03 M1.9 SF 73/3443 III/2 23 2014 2043 2100 ////// M1.5 ///3436 24 0317 0328 0336 S12E22 M4.4 1N 77/3445 24 1451 1500 1505 ////// M1.0 73/3443 III/2II/1 #--------------------------------------------------------------------# # Solar Influences Data analysis Center - RWC Belgium # # Royal Observatory of Belgium # # # # Website http://www.sidc.be. # # E-mail sidc-support@oma.be # # To unsubscribe http://www.sidc.be/registration/unsub.php # # # # Legal notices: # # - Intellectual Property Rights: # # http://www.astro.oma.be/common/internet/en/data-policy-en.pdf # # - Liability Disclaimer: # # http://www.astro.oma.be/common/internet/en/disclaimer-en.pdf # # - Use and processing of your personal information: # # http://www.astro.oma.be/common/internet/en/privacy-policy-en.pdf # #--------------------------------------------------------------------#