:Issued: 2024 Oct 30 1743 UTC :Product: documentation at http://www.sidc.be/products/bul #--------------------------------------------------------------------# # SIDC Weekly bulletin on Solar and Geomagnetic activity # #--------------------------------------------------------------------# WEEK 1243 from 2024 Oct 21 Solar Active Regions (ARs) and flares --------------- Solar flaring activity was at low levels at the start of the week. Activity reached high levels on October 24 and 26 and remained at moderate levels for the rest of the week. There were 22 active regions visible throughout the week. A total of 34 C-class flares, 7 M-class flares and 2 X-class flares were recorded. Throughout the week, most of the flaring activity was produced by NOAA ARs 3869, 3872, 3873 and 3878. The largest flare was an X3.3, with peak time 03:57 UTC on October 24, associated with NOAA AR 3869. Type II and Type IV radio emission were detected at 03:46 UTC on Oct 24 during the flaring activity. The second largest flare was an X1.8 flare, peaking at 07:19 UTC on October 26, produced by NOAA Active Region 3873. This event was also associated with a Type II and Type IV radio burst, detected at 06:29 UTC on October 26. Coronal mass ejections --------------------- Two fast halo CMEs were observed over the week. The first CME was observed in SOHO/LASCO-C2 coronagraph data starting at around 03:48 UTC on October 24, associated with the X3.3 flare from NOAA AR 3869. This CME, primarily directed to the southeast from Earth’s perspective, had an estimated speed exceeding 1300 km/s. While the bulk of the ejecta was expected to miss Earth, a glancing blow was expected to arrive on October 26. A shock associated with this CME was indeed detected in the solar wind at around 15:35 UTC on October 26. The second fast halo CME was recorded at 06:48 UTC on October 26, associated with an X1.8 flare from NOAA AR 3873. This CME also primarily directed to the southeast from Earth’s perspective with an estimated speed of approximately 1500 km/s. Analysis indicated that most of this CME’s ejecta would miss Earth, although a potential glancing blow was expected by October 28. This was confirmed when a shock was detected in the solar wind at around 04:17 UTC on October 28. Coronal Holes --------------------- Two coronal holes crossed the central meridian during the past week. The first, a small equatorial negative polarity coronal hole, fully crossed the central meridian on October 24. The second was a small, negative polarity, low-latitude coronal hole that crossed the central meridian on October 25. Proton flux levels --------------------- The greater than 10 MeV proton flux, as recorded by GOES-18, exceeded the 10 pfu threshold on October 26 at 19:10 UTC and continued rising, crossing the 100 pfu threshold at 09:15 UTC on October 27. This gradual increase began on October 24 at 04:15 UTC. Two halo coronal mass ejections (CMEs), along with strong flaring activity from NOAA AR 3869 and 3873, were likely associated with this particle event. Electron fluxes at GEO --------------------- The greater than 2 MeV electron flux, as measured by GOES 16 and GOES 18, was below the 1000 pfu threshold during the last week. The electron fluence was at normal levels throughout the entire week. Solar wind --------------------- The solar wind parameters reflected slow solar wind conditions at the beginning of the week. The solar wind parameters became slightly disturbed on October 22, likely due to the mild influence of a high-speed stream (HSS) from a positive polarity coronal hole that started to cross the central meridian on October 18. The interplanetary magnetic field (IMF) reached values up to 12 nT, and the solar wind speed increased from around 300 km/s to 430 km/s. After returning to slow solar wind conditions, they became enhanced again on October 26 due to the arrival of an ICME, possibly mixed with a mild HSS influence from a small negative polatiry coronal hole. A shock was detected in the solar wind data around 15:35 UTC on October 26, with the IMF jumping from 14 nT to 22 nT and the solar wind speed rising from 370 km/s to 440 km/s. This shock was likely associated with a halo coronal mass ejection observed early on October 24. Following the ICME's arrival, the IMF reached values up to 26 nT, and the southward component of the IMF fluctuated between -18 nT and 19 nT. Geomagnetism --------------------- Geomagnetic conditions over the past week were quiet to unsettled thoughout most of the week. Active conditions were recorded locally over Belgium (K-BEL: 4) between 15:00-18:00 UTC and 21:00-00:00 UTC on October 22, as well as globally (NOAA Kp: 4- to 4+) between 03:00 and 09:00 UTC on October 24, influenced by a high-speed stream (HSS). The arrival of an ICME led to further active levels reached both globally (NOAA Kp: 4 to 4+) and locally over Belgium (K-BEL: 4) between 18:00 and 00:00 UTC on October 26. --------------------------------------------------------------------------- DAILY INDICES DATE RC EISN 10CM Ak BKG M X 2024 Oct 21 /// 165 164 009 C2.8 0 0 2024 Oct 22 /// 117 176 007 C2.4 0 0 2024 Oct 23 159 119 185 009 C2.0 0 0 2024 Oct 24 /// 139 197 014 C2.1 1 1 2024 Oct 25 /// 176 209 002 C1.8 1 0 2024 Oct 26 /// 229 238 012 C3.6 4 1 2024 Oct 27 /// 240 246 012 C3.2 1 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 24 0330 0357 0428 S05E86 X3.3 SF 67/3869 VI/3III/2II/1IV/2 24 1022 1029 1034 S15E87 M1.2 SF 67/3869 25 0723 0733 0738 S10E75 M1.1 SF ///3873 III/3V/3 26 0557 0623 0632 S11E56 M9.5 3 ///3873 II/2IV/3 26 1136 1150 1157 ////// M2.2 /////// 26 1158 1206 1213 ////// M2.8 /////// 26 1404 1416 1430 S10E50 M1.6 S /////// VI/2 26 0632 0719 0756 S17E64 X1.8 2 ///3873 II/2IV/3 27 2305 2324 2344 ////// M2.8 ///3878 VI/2III/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 # #--------------------------------------------------------------------#