Viewing archive of Saturday, 27 July 2013

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2013 Jul 27 1348 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
27 Jul 2013	112	013
28 Jul 2013	114	003
29 Jul 2013	115	004

Bulletin

Catania sunspot group 35 (NOAA AR 1800) keeps the beta-gamma configuration of its photospheric magnetic field. It produced several weak C-class flares in the last 12 hours. We expect more C-class flares from this active region, with M-class flares possible but very unlikely. A partial halo CME (angular width around 135 degrees, principal angle 215 degrees) was detected by SOHO/LASCO yesterday first appearing in the LASCO C2 field of view at 18:36 UT. It was accompanied by the C1.5 flare peaking at 19:28 UT situated just behind the south-west limb (a post-eruption arcade was detected by SDO/AIA). The CME speed was around 500 km/s according to the CACTus software. Due to the CME source region position behind the limb, we do not expect the CME-associated interplanetary disturbance to arrive at the Earth. SDO/AIA observed a filament eruption accompanied by coronal dimmings and a post-eruption arcade in a bipolar magnetic region situated between Catania sunspot groups 35 and 44 (NOAA ARs 1800 and 1805). It was associated with the C1.8 flare peaking at 21:49 UT yesterday. There is no indication in the SOHO/LASCO and STEREO/COR data that this eruption was accompanied by a CME. The Earth is currently inside the trailing part of the fast solar wind stream. The wind speed is around 440 km/s and the interplanetary magnetic field magnitude is around 5-6 nT. Although Dourbes reported an interval of active geomagnetic conditions earlier today (K = 4 between 6 and 9 UT) in response to the passage of the fast flow, we expect quiet to unsettled geomagnetic conditions in the coming hours.

Today's estimated international sunspot number (ISN): 049, based on 07 stations.

Solar indices for 26 Jul 2013

Wolf number Catania	097
10cm solar flux	110
AK Chambon La Forêt	017
AK Wingst	012
Estimated Ap	014
Estimated international sunspot number	052 - Based on 15 stations

Noticeable events summary

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

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