Viewing archive of Wednesday, 27 September 2023

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2023 Sep 27 1233 UTC

SIDC Forecast

Solar flares

C-class flares expected, (probability >=50%)

Geomagnetism

Active conditions expected (A>=20 or K=4)

Solar protons

Quiet

	10cm flux	Ap
27 Sep 2023	159	012
28 Sep 2023	159	011
29 Sep 2023	159	010

Solar Active Regions and flaring

Solar flaring activity over the past 24 hours was at low levels. The largest flare was a C4.7-flare, with peak time 05:46 UTC on September 27, produced by an as yet unnumbered region rotating over the south-east limb. There are currently 6 numbered active regions on the visible disk. NOAA AR 3435 (beta-delta) and NOAA AR 3445 (beta-gamma) are both mostly stable, NOAA AR 3449 (beta-gamma) has emerged in the north- east quadrant producing 4 C-class flares and NOAA AR 3448 has decayed into a plage region, all other regions have simple alpha or beta magnetic field configurations. The solar flaring activity is likely to remain at low levels over the coming days with C-class flares expected, M-class flares possible and a low chance for isolated X-class flaring.

Coronal mass ejections

No Earth directed CMEs have been observed in the last 24 hours. Coronagraph data is still unavailable for the filament eruption reported on the 25 September. Any possible impact on Earth would consider to be minor.

Solar wind

In the last 24 hours, the interplanetary magnetic field fluctuated between 1 nT and 8 nT and the Bz was mostly negative going down to – 5 nT. The solar wind speed increased on September 26 up to around 531 km/s and has gradually been decreasing since 23:20 UTC on September 26. The phi-angle has been switching between the positive sector (directed away from the Sun) and negative sector. Slow solar wind conditions are expected in the next 24 hours, with a possibility of a slight enhancement on the 28 September due to filament eruption on the 25 September.

Geomagnetism

The geomagnetic conditions over the past 24 hours reached minor storm levels globally (Kp 5 +) and locally (K Bel 5) at the start of the period and decreased to quiet to active conditions by the end of the period. Quiet to active conditions are expected in the next 24 hours.

Proton flux levels

The greater than 10 MeV proton flux was at background level over the last 24 hours and is expected to remain so in the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES-16 stayed below threshold value. The greater than 2 MeV electron flux is expected to increase above the threshold in the next 24 hours. The 24h electron fluence became elevated but remained at nominal levels and is expected to remain at nominal levels in the next 24 hours.

Today's estimated international sunspot number (ISN): 137, based on 14 stations.

Solar indices for 26 Sep 2023

Wolf number Catania	143
10cm solar flux	165
AK Chambon La Forêt	035
AK Wingst	024
Estimated Ap	029
Estimated international sunspot number	151 - Based on 29 stations

Noticeable events summary

Provided by the Solar Influences Data analysis Center© - SIDC - Processed by SpaceWeatherLive

All times in UTC

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