:Issued: 2025 Jul 29 1232 UTC :Product: documentation at http://www.sidc.be/products/bul #--------------------------------------------------------------------# # SIDC Weekly bulletin on Solar and Geomagnetic activity # #--------------------------------------------------------------------# WEEK 1282 from 2025 Jul 21 Solar Active Regions (ARs) and flares --------------- Solar flaring activity was low during the week, with only C-class flares. The strongest flares were a C8.1 flare (SIDC Flare 4939) and a C7.4 flare (SIDC Flare 4944). The C8.1 flare, from beyond the west limb, peaked at 05:45 UTC on July 24. The C7.4 flare, associated with SIDC Sunspot Group 564 (NOAA Active Region 4149, magnetic type beta-gamma), peaked at 01:01 UTC on July 25. There was a total of twenty-four active regions on the visible disk during the week. The most complex were SIDC Sunspot Group 564 (NOAA Active Region 4149) and SIDC 572 (NOAA Active Region 4155), both developing to a magnetic type beta-gamma during the week. Coronal mass ejections --------------------- A few Coronal Mass Ejections (CMEs) were detected during the week. Almost all of them were either events near the west or east limb or backsided and had no impact on Earth. SIDC CME 528 was observed in LASCO/C2 and C3 coronagraph imagery starting from around 15:00 UTC on July 21, lifting off the east limb. No clear source was identified on the visible disk, suggesting a backsided event. A faint partial halo CME (SIDC CME 530) was observed in LASCO/C2 and C3 coronagraph imagery starting from around 08:00 UTC on July 23. The CME was probably associated with a filament eruption in the southwest quadrant seen in SUVI 304 data from around 02:30 UTC on July 23. Coronal Holes --------------------- An elongated, mid-latitude, negative polarity coronal hole (SIDC Coronal Hole 116) has crossed the central meridian between July 19 and July 21. An associated high-speed stream began arriving at Earth in the second half of July 22. A mid-latitude, negative polarity coronal hole (SIDC Coronal Hole 121) started crossing the central solar meridian on July 26. Proton flux levels --------------------- The greater than 10 MeV proton flux was below the 10 pfu threshold throughout the week. Electron fluxes at GEO --------------------- The greater than 2 MeV electron flux as measured by GOES 18 was mostly above the 1000 pfu threshold during the week. It dropped below the 1000 pfu threshold between approximately 20:00 UTC on July 22 and 13:00 UTC on July 24. The 24-hour electron fluence was at high levels at the beginning of the week and gradually decreased until it reached nominal levels around 17:00 UTC on July 23 and remained so for the following 24 hours. It then increased to moderate levels for the rest of the week. Solar wind --------------------- The solar wind parameters (ACE) were enhanced starting from the second half of July 22, under the influence of the high-speed stream associated with the negative polarity coronal hole (SIDC Coronal Hole 116). The solar wind speed peaked at 780 km/s on July 24, the interplanetary magnetic field values were between 4 nT and 24 nT, the Bz component varied between -14 nT and 17 nT. A gradual return to a slow solar wind regime followed. The solar wind conditions were slightly enhanced again on July 26 under the waning influence of the high-speed stream from the negative polarity coronal hole (SIDC Coronal Hole 116) and a possible, but less certain, ICME arrival associated with the Coronal Mass Ejection (SIDC CME 530) that lifted off around 08:00 UTC on July 23. The solar wind speed reached values around 610 km/s, the interplanetary magnetic field reached values up to 11 nT and the southward component of the interplanetary magnetic field dropped to -9 nT. Through the end of the week, solar wind parameters reflected mostly slow solar wind conditions. Geomagnetism --------------------- The global geomagnetic conditions briefly reached minor storm conditions (NOAA Kp 5) on July 22 and July 23, under the influence of the high-speed stream associated with the negative polarity coronal hole (SIDC Coronal Hole 116). Geomagnetic conditions globally and locally were mostly at quiet to unsettled levels (NOAA Kp 1 to 3, K BEL 1 to 3) during the rest of the week, with isolated active intervals (NOAA 4, K BEL 4) in the second half of July 26. --------------------------------------------------------------------------- DAILY INDICES DATE RC EISN 10CM Ak BKG M X 2025 Jul 21 178 145 143 004 C1.3 0 0 2025 Jul 22 134 114 145 015 C1.0 0 0 2025 Jul 23 118 112 150 032 B9.8 0 0 2025 Jul 24 131 122 148 020 B8.3 0 0 2025 Jul 25 211 159 148 012 B8.3 0 0 2025 Jul 26 /// 152 143 017 B7.1 0 0 2025 Jul 27 /// 142 145 004 B8.7 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 NONE #--------------------------------------------------------------------# # 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 # #--------------------------------------------------------------------#