SIDC Weekly Bulletin
Review of past solar and geomagnetic activity.| Source | SIDC (RWC-Belgium) |
| Frequency | Weekly |
| Format | Plain text |
| Mail header | SIDC Weekly Bulletin |
| SIDC code | bul |
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:Issued: 2025 Dec 15 1606 UTC :Product: documentation at http://www.sidc.be/products/bul #--------------------------------------------------------------------# # SIDC Weekly bulletin on Solar and Geomagnetic activity # #--------------------------------------------------------------------# WEEK 1302 from 2025 Dec 08 Solar Active Regions (ARs) and flares --------------- Solar flaring activity was high at the beginning of the week and gradually decreased to low levels by the end of the week. The strongest flare was an X1.1 flare (SIDC Flare 6337), which peaked at 05:01 UTC on December 8 and was associated with SIDC Sunspot Group 713 (NOAA Active Region 4298, magnetic type beta). Several M-class flares were observed between December 8 and December 12, mainly associated with SIDC Sunspot Group 709 (NOAA Active Region 4294), which was the most complex active region on the solar disk during the week, reaching a magnetic complexity of beta-gamma-delta early in the week before gradually decaying and rotating across the west limb. The total number of numbered active regions on the visible disk decreased from nine at the beginning of the week to four by December 14. Coronal mass ejections --------------------- Several Coronal Mass Ejections (CMEs) were observed during the week. All detected CMEs were associated with eruptions near the solar limb and were not expected to have a direct impact on Earth. A wide CME (SIDC CME 606) was observed in LASCO/C2 and C3 coronagraph imagery starting from around 05:20 UTC on December 8, lifting off the west limb and associated with the X1.1 flare. Another CME (SIDC CME 607) was observed in LASCO/C2 coronagraph data starting at 22:36 UTC on December 8. The CME was directed primarily to the west from the Earth's perspective and associated with the M1.2 flare (SIDC Flare 6344), peaking at 22:28 UTC on December 08. Later in the week, a wide CME (SIDC CME 608) was observed in LASCO/C2 and C3 coronagraph imagery starting from around 22:30 UTC on December 10, lifting off the west limb and associated with an M4.4 flare. A slow, wide CME (SIDC CME 609), associated with a prominence eruption observed in AIA 304 data at the southeast limb on December 12, was detected in LASCO/C2 coronagraph imagery starting around 04:00 UTC. Coronal Holes --------------------- An elongated, northern, negative polarity coronal hole (returning SIDC Coronal Hole 142) crossed the central meridian starting on December 10. The associated high-speed stream began influencing near-Earth space from December 12 onward and persisted through the end of the week. 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 measured by GOES 18 and GOES 19 was near or above the 1000 pfu threshold early in the week. Electron flux levels gradually decreased and remained below the 1000 pfu threshold from December 10 onward. The 24-hour electron fluence was at moderate levels early in the week and returned to normal levels by midweek, remaining nominal through December 14. Solar wind --------------------- Solar wind conditions (ACE) transitioned from a slow solar wind regime at the beginning of the week to enhanced conditions, initially due to the arrival of an ICME and subsequently under the influence of a high-speed stream. The ICME arrival was observed late on December 10, marked by an increase in solar wind speed to around 450 km/s, interplanetary magnetic field values reaching up to 18 nT, and a prolonged interval of southward Bz, with minimum values down to -16 nT. From December 12 onward, solar wind conditions were increasingly influenced by the high-speed stream associated with the negative polarity coronal hole (SIDC Coronal Hole 142). Solar wind speeds increased further, peaking near 690 km/s on December 14. Interplanetary magnetic field values varied between 2 nT and 16 nT, while the Bz component fluctuated between -14 nT and 16 nT. Enhanced solar wind conditions persisted through the end of the week. Geomagnetism --------------------- Geomagnetic activity reflected the combined effects of ICME influence and the influence of a high-speed stream later in the week. Global geomagnetic conditions reached moderate storm levels (NOAA Kp 6+) between December 10 and December 11, with locally observed K BEL values up to 6. Following this storm period, geomagnetic conditions remained unsettled to active, with recurrent minor storm intervals (NOAA Kp 5) observed between December 11 and December 13 under the continued influence of the high-speed stream. By December 14, geomagnetic conditions had relaxed to quiet to unsettled levels globally and locally. --------------------------------------------------------------------------- DAILY INDICES DATE RC EISN 10CM Ak BKG M X 2025 Dec 08 /// 166 186 001 C1.4 5 1 2025 Dec 09 182 152 183 004 C1.8 5 0 2025 Dec 10 133 128 168 028 C1.7 5 0 2025 Dec 11 138 115 146 029 C1.0 0 0 2025 Dec 12 144 094 135 033 C1.0 2 0 2025 Dec 13 /// 083 122 018 B7.3 0 0 2025 Dec 14 /// 071 119 008 B6.5 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 08 0033 0036 0039 S15W30 M2.0 1 21/4294 08 0449 0501 0504 S14W52 X1.1 2B 17/4298 III/3 08 0640 0654 0704 N22W09 M1.8 1 ///4304 III/1 08 1242 1305 1321 S17W48 M1.0 SF 21/4294 08 2113 2117 2125 N28W07 M3.1 SF 21/4294 08 2204 2228 2245 N22W27 M1.2 SN 24/4299 09 0037 0058 0117 ////// M2.0 24/4299 09 0134 0138 0142 ////// M1.1 21/4294 II/2 09 0741 0747 0751 S26E45 M1.6 SF 21/4294 VI/2III/2 09 1500 1514 1520 S13W51 M1.5 1 21/4294 09 2313 2327 2336 S17W44 M1.5 SF 23/4296 10 0417 0422 0427 S14W60 M1.2 SF 21/4294 III/2 10 0731 0737 0742 S15W62 M1.9 1N 21/4294 10 0946 0955 1002 ////// M1.0 21/4294 10 1332 1343 1349 S22W62 M1.6 SF 21/4294 III/2II/2 10 2158 2208 2214 S20W66 M4.4 2B 21/4294 V/3II/3 12 0450 0505 0514 ////// M2.0 23/4296 III/2CTM/1II/3 12 0527 0544 0553 ////// M1.1 21/4294 #--------------------------------------------------------------------# # 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 # #--------------------------------------------------------------------#
Details
This report is sent once a week, typically on a monday.The weekly bulletin gives an overview of solar and geomagnetic activity of the past week and includes a noticeable solar events list.
Check the ISES code book for information on ISES codes.