STCE Newsletter

1. Bumper cars
2. Review of Solar and Geomagnetic Activity
3. International Sunspot Number by SILSO
4. PROBA2 Observations
5. Noticeable Solar Events
6. Geomagnetic Observations in Belgium
7. Review of Ionospheric Activity
8. The SIDC Space Weather Briefing
9. Upcoming Activities

Bumper cars

NOAA 14566 (SIDC sunspot group 992 - https://www.sidc.be/services/event-chains/sunspots ) rotated onto the solar disk on 1 November as a small but wide bipolar sunspot group. Hardly a day later, a new active region started rapidly developing just behind (east of) the trailing portion of NOAA 14566, and by noon on 3 November, the leading portion had already bumped into the trailing main spot of NOAA 14566. As this new group grew in size and new magnetic flux emerged, several delta structures (two sunspots of opposite magnetic polarity very close together within the same penumbra) developed. This can be seen in the SDO/HMI images underneath with white light (top) and magnetograms (bottom). In the magnetograms, white denotes areas of positive magnetic polarity (magnetic field lines coming out of the Sun), black indicates areas of negative magnetic polarity (field lines returning to the Sun). Movies can be found in the online version of this newsitem at https://www.stce.be/news/842/welcome.html , running from 3 to 9 November at a cadence of 1 image per hour.

The complex magnetic structure of NOAA 14566 can also be seen in the overlay underneath, where an extreme ultraviolet image (SDO/AIA 171) is laid over a white light image (SDO/HMI). Both images were taken on 8 November at 13:00 UTC, and the combination shows the loops over NOAA 14566 as well as its connections with nearby smaller and or decaying groups such as NOAA 14569 to the west and NOAA 14568 to the east. "Bumper car" regions are well known for their ability to produce strong flares. One of the best examples is the 9 August 2011 event when -in an almost identical scenario- a strong flare was produced reaching a maximum intensity of nearly X10 (X6.9 in the old, uncorrected GOES scales). Eventually, it would turn out to be one of the strongest flares of the entire solar cycle 24. Movies and descriptions of this event can be found in the STCE's "Best of... 2011" space weather highlights overview at https://www.stce.be/news/353/welcome.html

It's no surprize then that space weather forecasters kept their eyes on rapidly evolving NOAA 14566. Its complex magnetic structure and the presence of the delta structures quickly increased the flare production of this active region. Yet, despite the size of the main spot, the flare activity remained mostly at C-class level, with only a handful of low-level M-class flares recorded. On 7 and on 8 November, the number of produced C-class flares was respectively 26 and 28 (from the daily NOAA event reports - https://www.spaceweather.gov/products/solar-and-geophysical-event-reports ), and almost exclusively produced by NOAA 14566. These values belong to some of the highest observed (per day!) so far this solar cycle. The left portion of the table underneath shows the days ranked according to the highest number of C-class flares, limited to days with 25 or more C-class events and for the current solar cycle (SC25) only. Note that double flares for the same event ("a flare with a double peak") are counted as one flare only.

In the right portion of the table, days are ranked according to the highest number of M- and X-class flares (summed). It only mentions those days with 14 or more M- and X-class flares, with the top day reaching 23 flare events on 29 December 2024 - that's basically 1 M- or X-class flare every hour!... Usually, for such high flare numbers, multiple flare-active sunspot groups are required ("Various" in the table). Occasionally, one active region is up to the task, such as NOAA 14366 early February this year. On 1 and 2 February 2026, it produced resp. 19 and 17 moderate and "extreme" flares, eventually becoming one of the most flare productive groups this solar cycle (see the table https://www.stce.be/sites/default/files/field/image/Afbeelding27.png at the STCE SC25 tracking page at https://www.stce.be/content/sc25-tracking#flares ). Note also the on-the-average 30% difference in the 10.7 cm solar radio flux between the left (about 150 sfu) and right (about 200 sfu) portion of the table. The radio flux is a parameter used in atmospheric drag calculations for satellite orbits, and expressed in solar flux units (sfu - https://www.stce.be/educational/acronym#S). Note also the lack of C-class flares in the right-hand portion of the table. Indeed, when the Sun is so actively flaring, it drives the background soft-x rays (SXR) flux to levels approaching M-class level, thus obscuring any C-class flares that are happening. This can be seen in the comparison underneath, with the upper graph showing the SXR flux evolution early February 2026 and the lower graph showing the SXR evolution early November 2026.

Review of Solar and Geomagnetic Activity

Solar Active Regions (ARs) and flares

Solar flaring activity was very low to low at the beginning of the week and increased to moderate levels during the second half of the week. Over the course of the week, eighty-five C-class flares and seven M-class flares were recorded. In total, eight active regions were observed on the visible solar disk.
SIDC Sunspot Group 992 (NOAA Active Region 4566) was the main driver of the flaring activity throughout the week and produced all M-class flares. The region rotated onto the visible solar disk from behind the east limb at the beginning of the week and remained the largest and most magnetically complex region (magnetic type beta-gamma-delta) on the visible solar disk through the whole week.
The largest flare was an M3.5 flare (SIDC Flare 8823), peaking at 18:33 UTC on November 5. Type II radio emission was detected at 18:28 UTC during this flaring activity. The remaining six M-class flares ranged from M1.1 to M1.9.

Coronal mass ejections

Several coronal mass ejections (CMEs) were detected in the available coronagraph imagery over the past week, but no clearly Earth-directed CMEs were identified. A slow and faint CME (SIDC CME 741) was observed in SOHO/LASCO-C2 coronagraph imagery from around 15:30 UTC on November 3, directed primarily towards the east from Earth's perspective. No clear source was identified on the visible solar disk, suggesting a possible backside origin. The CME was not expected to impact Earth.
A narrow CME (SIDC CME 742) was first observed in SOHO/LASCO-C2 coronagraph imagery at 19:12 UTC on November 5, directed predominantly towards the east from Earth's perspective. It was associated with the M3.5 flare (SIDC Flare 8823) produced by SIDC Sunspot Group 992. No impact at Earth was expected.
A glancing-blow arrival associated with SIDC CME 740, which lifted off the Sun on November 1, was expected around November 5. However, no clear ICME arrival signature was identified in the available solar wind data.

Coronal Holes

A recurrent negative polarity coronal hole (SIDC Coronal Hole 149) started to cross the central meridian around November 3. The associated high-speed stream started to influence the near-Earth solar wind environment from November 6.

Proton flux levels

The greater than 10 MeV proton flux, as measured by GOES-18 and GOES-19, remained below the 10 pfu threshold throughout the week.

Electron fluxes at GEO

The greater than 2 MeV electron flux, as measured by GOES-18 and GOES-19, crossed the 1000 pfu alert threshold several times during the week, mainly until November 6 and again from November 8.
The 24-hour electron fluence was mostly at moderate levels during the first part of the week and decreased to normal levels towards the end of the period.

Solar wind

At the beginning of the week, solar wind parameters reflected the waning influence of a high-speed stream associated with the equatorial positive polarity coronal hole SIDC CH 179. The solar wind speed gradually decreased from around 450 km/s to approximately 350 km/s by November 5. The interplanetary magnetic field remained weak, below 8 nT, and the magnetic field orientation was predominantly in the positive sector, with the field directed away from the Sun.
From November 6 onwards, solar wind conditions became slightly disturbed due to the arrival of a high-speed stream associated with the negative polarity coronal hole SIDC CH 149. The solar wind speed gradually increased from around 350 km/s to values exceeding 800 km/s on November 8. The interplanetary magnetic field reached values up to about 15 nT, while its north-south component, Bz, fluctuated between approximately -11 nT and 12 nT, with several southward intervals. The magnetic field orientation switched to the negative sector, with the field directed towards the Sun.
Solar wind conditions remained slightly disturbed under the ongoing influence of the high-speed stream for the remainder of the week.

Geomagnetism

Geomagnetic conditions were quiet to unsettled at the beginning of the week, both globally and locally over Belgium (NOAA Kp = 1 to 3+; K-Bel = 1 to 3). From November 7, geomagnetic activity increased following the arrival of the high-speed stream from the negative polarity coronal hole SIDC CH 149. Minor storm conditions were reached both globally and locally over Belgium on November 7-8, with NOAA Kp reaching 5+ and K-Bel reaching 5. Geomagnetic conditions remained mostly unsettled to active during the remainder of November 8.

International Sunspot Number by SILSO

The daily Estimated International Sunspot Number (EISN, red curve with shaded error) derived by a simplified method from real-time data from the worldwide SILSO network. It extends the official Sunspot Number from the full processing of the preceding month (green line), a few days more than one solar rotation. The horizontal blue line shows the current monthly average. The yellow dots give the number of stations that provided valid data. Valid data are used to calculate the EISN. The triangle gives the number of stations providing data. When a triangle and a yellow dot coincide, it means that all the data is used to calculate the EISN of that day.

PROBA2 Observations

Solar Activity

Solar flare activity fluctuated from low to moderate during the week.
In order to view the activity of this week in more detail, we suggest to go to the following website from which all the daily (normal and difference) movies can be accessed: https://proba2.oma.be/ssa
This page also lists the recorded flaring events.

A weekly overview movie (SWAP week 867) can be found here: https://proba2.sidc.be/swap/data/mpg/movies/weekly_movies/weekly_movie_2026_11_02.mp4.

Details about some of this week's events can be found further below.

If any of the linked movies are unavailable they can be found in the P2SC movie repository here: https://proba2.oma.be/swap/data/mpg/movies/.

Thursday November 05

The largest flare of this week was an M3.5, and it was observed by LYRA (top panel) and SWAP (bottom panel). The flare peaked on 2026-Nov-05 at 18:33 UT and occurred in the south-eastern quadrant of the Sun, originating from active region NOAA4566 (SIDC 992).
Find a SWAP movie of the event here: https://proba2.sidc.be/swap/movies/20261105_swap_movie.mp4.

Noticeable Solar Events

DAY	BEGIN	MAX	END	LOC	XRAY	OP	10CM	TYPE	Cat	NOAA
05	1821	1833	1841	S9E35	M3.5	2		II/2	85	4566
07	1226	1243	1248		M1.2					4566
07	1711	1717	1724		M1.4					4566
07	1821	1842	1856		M1.9					4566
08	0733	0746	0754	S8W3	M1.7	1F				4566
08	1529	1537	1549	S7W1	M1.1	1				4566
08	1815	1827	1835		M1.1					4566

LOC: approximate heliographic location	TYPE: radio burst type
XRAY: X-ray flare class	Cat: Catania sunspot group number
OP: optical flare class	NOAA: NOAA active region number
10CM: peak 10 cm radio flux

Geomagnetic Observations in Belgium

Local K-type magnetic activity index for Belgium based on data from Dourbes (DOU) and Manhay (MAB). Comparing the data from both measurement stations allows to reliably remove outliers from the magnetic data. At the same time the operational service availability is improved: whenever data from one observatory is not available, the single-station index obtained from the other can be used as a fallback system.
Both the two-station index and the single station indices are available here: http://ionosphere.meteo.be/geomagnetism/K_BEL/

Review of Ionospheric Activity

VTEC time series at 3 locations in Europe from 2 Nov 2026 till 8 Nov 2026

The top figure shows the time evolution of the Vertical Total Electron Content (VTEC) (in red) during the last week at three locations:
a) in the northern part of Europe(N 61deg E 5deg)
b) above Brussels(N 50.5deg, E 4.5 deg)
c) in the southern part of Europe(N 36 deg, E 5deg)
This top figure also shows (in grey) the normal ionospheric behaviour expected based on the median VTEC from the 15 previous days.

The time series below shows the VTEC difference (in green) and relative difference (in blue) with respect to the median of the last 15 days in the North, Mid (above Brussels) and South of Europe. It thus illustrates the VTEC deviation from normal quiet behaviour.

The VTEC is expressed in TECu (with TECu=10^16 electrons per square meter) and is directly related to the signal propagation delay due to the ionosphere (in figure: delay on GPS L1 frequency).
The Sun's radiation ionizes the Earth's upper atmosphere, the ionosphere, located from about 60km to 1000km above the Earth's surface.The ionization process in the ionosphere produces ions and free electrons. These electrons perturb the propagation of the GNSS (Global Navigation Satellite System) signals by inducing a so-called ionospheric delay.

See http://stce.be/newsletter/GNSS_final.pdf for some more explanations; for more information, see https://gnss.be/SpaceWeather

The SIDC Space Weather Briefing

The SIDC briefing presented by the forecaster on duty giving an overview of space weather from November 2 to 8 : https://www.stce.be/briefings/20261109_SWbriefing.pdf

Upcoming Activities

Courses, seminars and events with the Sun-Space-Earth system and Space Weather as the main theme. We provide occasions to get submerged in our world through educational, informative and instructive activities.

* Nov 23-25, 2026, STCE course: Role of the ionosphere and space weather in military communications, Brussels, Belgium - register: https://events.spacepole.be/event/259/
* Nov 30, 2026, Watching the Sun: a 200-year journey, guided tour Solar Physics, Ukkel, Belgium - register https://events.spacepole.be/category/2/
* Dec 7-9, 2026, STCE Space Weather Introductory Course for Aviation, Brussels, Belgium - register: https://events.spacepole.be/event/262/ - Fully booked

To register for a course and check the seminar details, navigate to the STCE Space Weather Education Center: https://www.stce.be/SWEC
If you want your event in the STCE newsletter, contact us: stce_coordination at stce.be

Website: https://www.stce.be/SWEC