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Bulletin quotidien sur l'activité solaire et géomagnétique du SIDC

Publié: 2021 Apr 25 1241 UTC

Prévisions SIDC

Éruptions solaires

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

Géomagnétisme

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

Moniteur de Flux de Proton

Quiet

	Flux de 10 cm	Ap
25 Apr 2021	079	019
26 Apr 2021	080	011
27 Apr 2021	081	006

Bulletin

Number of B-class and one C-class flares were reported during last 24 hours. Majority of the flaring activity originated from the Catania sunspot group 89 (NOAA AR 2820). The C2.6 flare (peaked at 01:35 UT on April 25) originated from the Catania sunspot group 87 (NOAA AR 2816). The flare was associated with the EUV wave, coronal dimmings and rather narrow CME as seen in the available SOHO/LASCO C2 and STEREO/COR2 observations. We expect the present level of the solar flaring activity to persist in the coming hours. We expect B-class and C-class flares while M-class flares are, although possible, not very probable. There were no Earth directed CMEs observed during last 24 hours and the proton flux levels remained at background values.

The greater than 2MeV electron flux was most of the time above the 1000 pfu threshold, and it is expected to stay so in the coming hours. The 24h electron fluence is at moderate level and is likely it will stay so in the next 24 hours.

The solar wind speed is presently about 480 km/s and the interplanetary magnetic field magnitude is about 7 nT. The in situ observations show arrival of the shock wave at about 22:27 UT on April 24. The sudden increase of the interplanetary magnetic field strength (from 5 to 10 nT), was simultaneous with the density, solar wind velocity and temperature increase. The shock wave was driven by the partial halo CME first seen in the SOHO LASCO C2 field of view at about 06:12 UT on April 22. The CME was associated with C3.8 flare (peaked at 04:35 UT) that originated from the Catania sunspot group 87 (NOAA AR 2816) at that moment situated at the center of the solar disc. The CME arrived to Earth about half a day earlier then expected. This discrepancy is possibly due to uncertainty in the estimation of the halo and partial halo CME speeds. Arrival of the shock wave induced disturbed geomagnetic conditions (Kp=4 and K=5, reported by Dourbes and NOAA respectively) from about midnight until 04 UT this morning. The geomagnetic conditions are presently unsettled to quiet and we expect them to stay so in the coming hours.

Estimation du nombre international de taches solaires (ISN) pour aujourd'hui : 053, sur la base de 20 stations.

Indices solaires pour 24 Apr 2021

Nombre de Wolf, observé par Catania	///
Flux solaire à 10 cm	079
AK Chambon La Forêt	023
AK Wingst	008
Ap estimé	008
Nombre international de taches solaires estimé	055 - Basé sur 32 stations

Résumé des événements marquants

Données fournies par le Solar Influences Data analysis Center© - SIDC - Traité par SpaceWeatherLive

Toutes les heures sont indiquées en UTC

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