:Issued: 2026 Mar 03 1606 UTC :Product: documentation at http://www.sidc.be/products/bul #--------------------------------------------------------------------# # SIDC Weekly bulletin on Solar and Geomagnetic activity # #--------------------------------------------------------------------# WEEK 1313 from 2026 Feb 23 Solar Active Regions (ARs) and flares --------------- Solar flaring activity was generally low throughout the week, with predominantly C-class flares and one M-class flare. The strongest flare was an M2.3 flare from the east limb (SIDC Flare 7072), peaking at 15:59 UTC on February 25. The number of active regions on the visible disk increased during the week, from one at the beginning of the week to seven by March 01. Early in the week, SIDC Sunspot Group 799 (magnetic type beta) emerged and then decayed into a plage by February 24. SIDC Sunspot Group 800 (magnetic type alpha), rotated onto the disk on February 25. By mid-to-late week, the most complex region was SIDC Sunspot Group 803 (NOAA Active Region 4380), which after rotating onto the visible disk from the east limb, was classified as beta-gamma and subsequently showed a gradual decrease in magnetic complexity. Additional regions rotated onto the disk or emerged during the week, contributing to the increase in the number of active regions on the visible disk by the end of the period. Coronal mass ejections --------------------- A coronal mass ejection (SIDC CME 629) was observed in LASCO/C2 coronagraph data starting at around 07:00 UTC on February 25. The CME was directed primarily to the north from Earth's perspective and was most likely associated with a filament eruption observed around 06:00 UTC on February 25 near the central meridian in the mid-latitude northern hemisphere. The bulk of the ejecta was expected to miss Earth and a glancing blow could not be excluded around February 28. No clear arrival signatures attributable to this CME were identified in near-Earth solar wind observations during the period covered by this report. Coronal Holes --------------------- A recurrent, negative polarity, equatorial coronal hole (SIDC Coronal Hole 147) was the dominant feature early in the week, driving a high-speed stream that influenced near-Earth space. In addition, a small, mid-latitude, positive polarity coronal hole (returning SIDC Coronal Hole 151) was reported crossing the central meridian during the week. Proton flux levels --------------------- The greater than 10 MeV proton flux remained below the 10 pfu threshold throughout the week. Electron fluxes at GEO --------------------- The greater than 2 MeV electron flux measured by GOES 18 and GOES 19 was generally around or above the 1000 pfu threshold during most of the week, with brief intervals below the threshold. The 24-hour electron fluence was at normal levels early in the week and was predominantly at moderate levels from midweek through the end of the week. Solar wind --------------------- Solar wind conditions transitioned from enhanced conditions early in the week to mostly slow solar wind conditions by the end of the week. The week began under the continuing influence of a high-speed stream associated with SIDC Coronal Hole 147, with elevated solar wind speeds typically between 560 and 740 km/s early in the period. Interplanetary magnetic field values were generally up to around 10 nT, with the Bz component fluctuating between about -9 nT and 9 nT at the beginning of the week. As the week progressed, the high-speed stream influence waned and solar wind speeds decreased toward a slow solar wind regime, reaching roughly 370 to 450 km/s late in the week. Geomagnetism --------------------- Geomagnetic activity was elevated at the beginning of the week, with unsettled to active levels and minor storm intervals occurring between 21:00 UTC on February 22 and 00:00 UTC on February 23 and between 03:00 UTC and 06:00 UTC on February 23 (NOAA Kp reaching 5- to 5; locally K BEL up to 5). After this, geomagnetic conditions were mostly quiet to unsettled, with occasional active intervals both globally and locally. --------------------------------------------------------------------------- DAILY INDICES DATE RC EISN 10CM Ak BKG M X 2026 Feb 23 036 008 108 028 B2.9 0 0 2026 Feb 24 000 006 120 018 B7.6 0 0 2026 Feb 25 045 015 125 019 B8.8 1 0 2026 Feb 26 040 034 130 019 B5.9 0 0 2026 Feb 27 044 046 139 010 B6.3 0 0 2026 Feb 28 /// 058 141 010 C1.0 0 0 2026 Mar 01 /// 084 147 010 B6.8 0 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 25 1535 1559 1609 ////// M2.3 ///4380 #--------------------------------------------------------------------# # 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 # #--------------------------------------------------------------------#