:Issued: 2010 May 04 1338 UTC :Product: documentation at http://www.sidc.be/products/bul #--------------------------------------------------------------------# # SIDC Weekly bulletin on Solar and Geomagnetic activity # #--------------------------------------------------------------------# WEEK 487 from 2010 Apr 26 SOLAR ACTIVITY -------------- The visible solar disk was spotless until April 29 when sunspot group NOAA number 11063 (Catania 66) was reported. On May 1 sunspot group NOAA 11064 appeared, but these sunspot groups didn\\\'t produce any flare beyond the B level. Flaring activity was low the whole week, on April 30 - May 1 there were two C-class flares associated with an unnumbered active region rotating into the solar disk. There was an important coronal hole facing the Earth on April 30. GEOMAGNETIC ACTIVITY -------------------- The geomagnetic conditions were quiet until April 29 when unsettled periods were observed due to a weak coronal hole solar wind stream. On May 2 the fast solar wind from another coronal hole arrived to the Earth. This solar wind stream arrived earlier and stronger than predicted and caused a major geomagnetic storm with Kp reaching 6 and lasting over a day. --------------------------------------------------------------------------- DAILY INDICES DATE RC EISN 10CM Ak BKG M X 2010 Apr 26 000 000 76 002 A3.5 0 0 2010 Apr 27 000 000 75 007 A3.1 0 0 2010 Apr 28 023 003 76 004 A3.1 0 0 2010 Apr 29 000 000 76 006 A4.4 0 0 2010 Apr 30 012 007 79 004 A5.1 0 0 2010 May 01 /// 010 78 004 A5.0 0 0 2010 May 02 /// 008 80 034 A5.8 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 # #--------------------------------------------------------------------#