Viewing archive of Saturday, 25 September 2021

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2021 Sep 25 1239 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
25 Sep 2021	088	003
26 Sep 2021	088	011
27 Sep 2021	090	025

Bulletin

Named regions present on the visible solar disk are Catania 45/NOAA 2871, Catania 44/NOAA 2872, Catania 43/NOAA 2873, Catania 48/NOAA 2875 and NOAA 2876. Catania 45/NOAA 2871 has been the source of a C.14-class flare. Two new regions should emerge on the visible disk, as seen in Stereo-A. Over the next 24 hours, C-class flares can be expected.

A CME associated with the M1.8 class flare on Sep 23 15:23UT can be expected about Sep 27. A CME associated with the filament eruption on Sep 25 17:12UT is been currently investigated.

The greater than 10 MeV proton flux was at background levels in the past 24 hours, and is expected to stay at nominal levels in the next 24 hours. The greater than 2 MeV electron flux remained below the 1000 pfu alert threshold. Over the next 24 hours, it is expected to increase towards the threshold. The 24h electron fluence was at nominal levels over the past 24 hours. Over the next 24 hours they are expected to remain at those levels, increasing towards moderate levels.

Over the past 24 hours the solar wind speed continued to increase, reaching 575 km/s. The total magnetic field strength had values between 1 and 7 nT, while its Bz component varied between -5 and 5nT. Solar wind parameters are expected to gradually decrease before possibly compound effects from the high sped stream of the coronal hole crossing central meridian on Sep 24, together with the two expected CMEs from Sep 23 can be detected near Earth from late Sep 26.

Geomagnetic conditions were at quiet to unsettled levels, (NOAA Kp 0-2 and K Dourbes 0-3) over the past 24 hours. Quiet to unsettled conditions can be expected over the next 24 hours.

Today's estimated international sunspot number (ISN): 044, based on 20 stations.

Solar indices for 24 Sep 2021

Wolf number Catania	071
10cm solar flux	088
AK Chambon La Forêt	014
AK Wingst	008
Estimated Ap	007
Estimated international sunspot number	056 - Based on 26 stations

Noticeable events summary

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

All times in UTC

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