:Issued: 2010 Oct 25 1457 UTC :Product: documentation at http://www.sidc.be/products/bul #--------------------------------------------------------------------# # SIDC Weekly bulletin on Solar and Geomagnetic activity # #--------------------------------------------------------------------# WEEK 512 from 2010 Oct 18 SOLAR ACTIVITY -------------- Solar activity was low during the whole week. Only 4 C-flares were produced by active region NOAA11112, mainly on Oct.18 and 19. Thereafter, this active region decayed until it disappeared at the West limb on Oct. 21. A few other H-type spots were present but without any significant flaring activity. The only other noteworthy solar event was a filament ejection and associated semi-halo CME that took place near central meridian early on Oct. 22. A trans-equatorial coronal hole passed the central meridian on Oct.21 and was probably the source of a geomagnetic disturbance at the end of the week. GEOMAGNETIC ACTIVITY -------------------- Geomagnetic activity was at quiet levels from Oct.18 until Oct.22. During that time period, the solar wind speed remained at a low speed of about 400km/s. Temporary negative excursions of the Bz component of the interplanetary magnetic field caused temporary unsettled conditions on Oct.19. Then, in the second half of Oct.22, the solar wind speed jumped to 680 km/s, due to a fast solar wind stream associated with the above-mentioned coronal hole. This caused unsettled to active geomagnetic conditions during two days, on Oct. 23 and 24, with short minor geomagnetic storm intervals mainly on Oct. 23. By th end of the week, the solar wind speed was slowly declining and the geomagnetic activity decreased to unsettled levels. --------------------------------------------------------------------------- DAILY INDICES DATE RC EISN 10CM Ak BKG M X 2010 Oct 18 /// 039 91 008 B1.1 0 0 2010 Oct 19 /// 046 87 007 B1.3 0 0 2010 Oct 20 062 033 84 006 A9.8 0 0 2010 Oct 21 048 024 84 004 A5.8 0 0 2010 Oct 22 /// 023 82 007 A7.1 0 0 2010 Oct 23 053 029 84 029 A6.7 0 0 2010 Oct 24 /// 034 82 020 A8.5 0 0 # RC : Sunspot index (Wolf Number) from Catania Observatory (Italy) # EISN : Estimated International Sunspot Number # 10cm : 10.7 cm radioflux (DRAO, Canada) # Ak : Ak Index Wingst (Germany) # BKG : Background GOES X-ray level (NOAA, USA) # M,X : Number of X-ray flares in M and X class, see below (NOAA, USA) --------------------------------------------------------------------------- NOTICEABLE EVENTS DAY BEGIN MAX END LOC XRAY OP TENCM TYPE Cat NOAA NOTE #--------------------------------------------------------------------# # Solar Influences Data analysis Center - RWC Belgium # # Royal Observatory of Belgium # # Fax : 32 (0) 2 373 0 224 # # Tel.: 32 (0) 2 373 0 491 # # # # For more information, see http://www.sidc.be. Please do not reply # # directly to this message, but send comments and suggestions to # # 'sidctech@oma.be'. If you are unable to use that address, use # # 'rvdlinden@spd.aas.org' instead. # # To unsubscribe, visit http://sidc.be/registration/unsub.php # #--------------------------------------------------------------------#