:Issued: 2013 May 02 1112 UTC :Product: documentation at http://www.sidc.be/products/bul #--------------------------------------------------------------------# # SIDC Weekly bulletin on Solar and Geomagnetic activity # #--------------------------------------------------------------------# WEEK 643 from 2013 Apr 22 SOLAR ACTIVITY --------------- Solar Flaring activity was dominated by NOAA AR 1726 (Cat 51, beta-gamma-delta) which produced a large number of C-class flares. The biggest event of the period was however only a short-duration M1.0 flare on April 22. NOAA AR 1726 crossed the NE limb on April 26. After that NOAA AR 1731 (Cat 57), at the NE limb was the dominant region with a beta-gamma configuration. Proton >10 MeV fluxes had two excursions, on April 21 09:54 (just before the present reporting period) and again on April 25. The event threshold was however never crossed. GEOMAGNETIC ACTIVITY --------------------- A recurrent coronal hole in the Southern hemisphere drove the geomagnetic activity during the period. The solar wind speed, as measured by the ACE satelleite, was 250 km/s in the beginning of the period and rose monotonically up till 550 km/s on late April 25 till April 27. Towards the end of the period, the solar wind speed decreased again to 400 km/s. The associated co-rotating interactive region pushed up the solar wind density and IMF on April 24 and April 25. Local K-index (Chambon La Foret) and NOAAs estimated Kp index reached values 4. Several halo CME alerts were issued by CACTus during the period but none of these was Earth-directed. --------------------------------------------------------------------------- DAILY INDICES DATE RC EISN 10CM Ak BKG M X 2013 Apr 22 /// 032 113 006 B3.7 1 0 2013 Apr 23 /// 028 118 008 B4.9 0 0 2013 Apr 24 /// 031 115 024 B5.6 0 0 2013 Apr 25 /// 044 119 014 B7.3 0 0 2013 Apr 26 /// 027 122 018 B6.9 0 0 2013 Apr 27 /// 026 127 009 B8.4 0 0 2013 Apr 28 /// 023 132 009 B6.9 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 SUMMARY DAY BEGIN MAX END LOC XRAY OP 10CM RADIO BURST TYPES Catania NOAA 22 1022 1029 1031 ////// M1.0 III/3V/3 1726 #--------------------------------------------------------------------# # 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 # #--------------------------------------------------------------------#