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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2019 May 11 1230 UTC

SIDC Forecast

Brillamenti solari

Quiet conditions (<50% probability of C-class flares)

Geomagnetism

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

Protoni solari

Quiet

	10cm flux	Ap
11 May 2019	075	029
12 May 2019	074	010
13 May 2019	073	007

Bulletin

X-ray flux remained below C level and with both regions on disk (Catania groups 16 and 17 or NOAA AR 2740 and 2741) simple and inactive, this is expected to remain so.

In the vicinity of Catania group 16 (NOAA AR 2740), located near disk centre, two material eruptions can be seen in EUV images. The first around 18:25UT and the second around 23:55UT. Coronagraph images from STEREO A also confirm two corresponding CMEs. In currently available coronagraph images from Earth perspective the signatures are less clear. SoHO/LASCO C2 shows, from around 3:02UT, a mainly North-East bound CME of which the angular extent is hard to estimate given the faint signature. It could however be classified as partial halo and correspondingly the presence of an Earth directed component must be considered. With the initiation parameters unclear, the interplay between both CME's is hard to assess. Speed is best estimated from STEREO A data and is for both CMEs low, 300-400 km/s. Based on these initiation parameters, a possible arrival of these CME's is not expected before noon, May 15 and 7:00UT, May 16 respectively.

Solar proton flux levels were at background values and are expected to remain so.

Solar wind conditions were nominal until 16:55UT, when a weak shock appeared in Solar wind data. Solar wind speed jumped from 340km/s to only just over 380 km/s. Total magnetic field increased from under 5nT to almost 9 nT. These observed enhancements are probably signatures of the expected May 6 CME. Total magnetic field reached further to 12.5nT and the Bz component saw periods of pronounced negative values down to -11.5nT. The phi angle switched into the positive sector after 6:00UT. Solar wind speed is currently at 350 km/s with Bz around -9.5nT already for about 6 hours. These perturbations in the interplanetary magnetic field are expected to continue over the day before subsiding. Later nominal conditions are expected until May 15 when we may see enhancements related to the May 10/11 CME(s).

Geomagnetic conditions have been active (local K Dourbes 4) with minor storm levels reached at planetary level (NOAA Kp 5). Further active conditions and possibly minor storm episodes are possible in the next 12-24 hours but geomagnetic conditions should ease down to unsettled levels by the end of the period.

Today's estimated international sunspot number (ISN): 031, based on 15 stations.

Solar indices for 10 May 2019

Wolf number Catania	///
10cm solar flux	076
AK Chambon La Forêt	020
AK Wingst	010
Estimated Ap	009
Estimated international sunspot number	028 - Based on 26 stations

Noticeable events summary

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

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