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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2015 Apr 24 1230 UTC

SIDC Forecast

Brillamenti solari

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

Geomagnetism

Quiet (A<20 and K<4)

Protoni solari

Quiet

	10cm flux	Ap
24 Apr 2015	137	006
25 Apr 2015	133	011
26 Apr 2015	129	013

Bulletin

Solar flaring activity was at low levels with several low C flares occurring over the past 24 hours. Most of these originated from Catania group 39 (NOAA region 2326). This region also produced the largest flare of the period, a C7.3 flare peaking at 12:03 UT in the decay phase of yesterdays M1.1 flare from Catania group 28 (NOA 2322). Further C flares were recorded from Catania groups 33 and 44 (NOAA 2325 and 2333 respectively). The most significant evolution was witnessed in Catania group 39 (NOAA 2326) which was also the most active region of the period. Also groups 37 and 38 (NOAA 2331 and 2327) showed some growth over the period. We expect C flaring over the next days. An asymmetric full halo CME is visible in SoHO/LASCO coronagraph data. In C3 data it is visible from 10:06UT (April 23) onwards departing the western limb. Reported projected speeds vary between 500 and 1000 km/s. The CME is related to the M1.1 flare peaking at 10:07 UT originating from Catania group 28 (NOAA 2322) located behind the western limb. An off limb darkening is visible at that time in SDO/AIA 193 images. The event is thus a limb event and even rather a backsided event than a frontsided event. It is believed not to have any influence on Earth. Solar wind conditions continued to stabilize at nominal levels. Solar wind speed decreased from 440 km/s to 380 km/s. Total magnetic field was in the 4-6nT range with Bz variable in the +-4nT range. Magnetic field phi angle was stable in the outward sector. Geomagnetic conditions were quiet to unsettled (NOAA Kp 0-3 and local K Dourbes 0-2). The CME of April 18 is no longer expected to arrive, and hence nominal wind conditions and quiet to unsettled geomagnetic conditions are expected for the next 48 hours. There is, however, a possibility that a possible sector boundary change may slightly enhance solar wind conditions.

Today's estimated international sunspot number (ISN): 064, based on 17 stations.

Solar indices for 23 Apr 2015

Wolf number Catania	165
10cm solar flux	141
AK Chambon La Forêt	010
AK Wingst	006
Estimated Ap	006
Estimated international sunspot number	084 - Based on 30 stations

Noticeable events summary

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

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