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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2014 Sep 24 1232 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 Sep 2014	142	016
25 Sep 2014	146	011
26 Sep 2014	150	010

Bulletin

Solar flaring activity has been moderate. An isolated M2.3 flare was produced by NOAA AR 2172 peaking at 23:16 UT. It was associated with a dimming as well as type II radio burst detections (Learmonth estimated shock speed 790-1250 km/s). A corresponding CME observed by STEREO B COR2 departing the west limb (as seen from STEREO B) does not appear to be fast nor very wide. SOHO/LASCO data for the relevant time slot just became available and records the CME in C2 data from midnight onwards. This imagery confirms the small angular width (roughly about 120 degrees) and indicates a primary direction towards the east. With the small recorded speeds (plane of the sky projected speed around 300 km/s) even a glancing blow seems unlikely. With background Xray flux around the B6 level and NOAA AR 2171 the only significant potential flaring source we expect flaring at C-level although their is a fair chance for another M flare from this region as it continues to evolve and grow in size. Another asymmetric halo CME was detected with first appearance in SOHO/LASCO coronagraph images at 19:00 UT, for which Cactus has sent out a corresponding alert. Despite a data gap in STEREO B EUVI 193 data between 18:16UT and 21:26 UT the start of the eruption (from the same active region as the previous two partial/asymmetric halo CME's) was recorded just before the data gap, as well as the post flare loops just after the data gap. The event is thus judged to be backsided. Solar wind speed dropped further during the first half of the reporting period to a minimum of close to 370 km/s around 19:00 UT. It increased afterwards to around 420 km/s presently. The total magnetic field slightly increased to above the 7 nT level with periods of Bt 8nT and negative BZ around -7nT. Unsettled to active geomagnetic conditions have been recorded (NOAA Kp 3-4, local hourly K Dourbes 1-4). Similar solar wind conditions and quiet to unsettled geomagnetic conditions with possible active periods are expected to continue over the next days.

Today's estimated international sunspot number (ISN): 076, based on 08 stations.

Solar indices for 23 Sep 2014

Wolf number Catania	///
10cm solar flux	138
AK Chambon La Forêt	021
AK Wingst	014
Estimated Ap	014
Estimated international sunspot number	088 - Based on 23 stations

Noticeable events summary

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

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