Viewing archive of Friday, 18 September 2015

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2015 Sep 18 1230 UTC

SIDC Forecast

Solar flares

M-class flares expected (probability >=50%)

Geomagnetism

Minor storm expected (A>=30 or K=5)

Solar protons

Quiet

	10cm flux	Ap
18 Sep 2015	109	026
19 Sep 2015	109	027
20 Sep 2015	109	015

Bulletin

NOAA 2415 remains magnetically complex, with a weakening delta but also with some new opposite polarity flux emerging in front (to the west) of the main spot. Ten C-class flares were observed, all produced by NOAA 2415. The strongest was a C6.7 peaking at 21:15UT. NOAA2419 showed some interaction with NOAA 2415 during/following a long duration C2.6 flare that started at 04:22UT and peaked at 06:31UT. Some coronal dimming to the west of NOAA 2415 was observed, as well as a Type II radio-burst. Standing-by coronagraphic imagery to evaluate the effects of the associated coronal mass ejection.

More C-class flares are expected, with a chance on an M-class flare from NOAA 2415.

Solar wind speed continued its gradual decline from its initial values near 460 km/s to its current 400 km/s. Bz varied between -6 and +4 nT, being predominantly negative after 21:00UT. The interplanetary magnetic field pointed mostly away from the Sun. Quiet to unsettled conditions were observed, with active episodes around midnight observed in Dourbes.

Quiet to active geomagnetic conditions are expected. Minor geomagnetic storming is possible late on 18 or on 19 September in response to the anticipated arrival of the high speed stream of a transequatorial coronal hole.

Today's estimated international sunspot number (ISN): 069, based on 22 stations.

Solar indices for 17 Sep 2015

Wolf number Catania	081
10cm solar flux	107
AK Chambon La Forêt	014
AK Wingst	014
Estimated Ap	014
Estimated international sunspot number	068 - Based on 24 stations

Noticeable events summary

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

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