:Issued: 2010 Dec 21 0853 UTC :Product: documentation at http://www.sidc.be/products/bul #--------------------------------------------------------------------# # SIDC Weekly bulletin on Solar and Geomagnetic activity # #--------------------------------------------------------------------# WEEK 520 from 2010 Dec 13 SOLAR ACTIVITY ------------- The strongest solar event in this period was a C5.3 flare from active region NOAA 11135 on Dec 15. Other noteworthy activity was a long duration C2.3 flare on Dec 14 from NOAA 11134. >From Dec 15-16 onwards, the complex of NOAA active regions 11131, 11133 and 11134 in the Northern solar hemisphere rotated behind the solar limb, resulting in a downward trend in all solar indices (F10.7, GOES X-ray curves and the LYRA and SWAP curves). An SIDC all quiet alert was issued from Saterday Dec 18 onwards. GEOMAGNETIC ACTIVITY ------------------- Geomagnetic activity was low this week and characterized by the passage of a high speed solar wind stream. The solar wind started the period at about 400 km/s and went up over 600 km/s on Dec 14. After that, a gradual decrease was observed down to again 400 km/s by the end of the period. Geomagnetic activity was strongest on Dec 14 and early Dec 15 with up to 1 episode of K=4. For the rest of the period geomagnetic activity was typically at K=2 levels. --------------------------------------------------------------------------- DAILY INDICES DATE RC EISN 10CM Ak BKG M X 2010 Dec 13 048 026 88 010 B1.1 0 0 2010 Dec 14 033 015 90 019 B1.0 0 0 2010 Dec 15 /// 008 87 010 A9.9 0 0 2010 Dec 16 023 015 84 008 A8.9 0 0 2010 Dec 17 011 007 82 006 A6.7 0 0 2010 Dec 18 011 000 81 003 A5.1 0 0 2010 Dec 19 /// 000 81 004 A4.3 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 # #--------------------------------------------------------------------#