:Issued: 2010 May 25 1405 UTC :Product: documentation at http://www.sidc.be/products/bul #--------------------------------------------------------------------# # SIDC Weekly bulletin on Solar and Geomagnetic activity # #--------------------------------------------------------------------# WEEK 490 from 2010 May 17 SOLAR ACTIVITY ------------ There was a filament disappearance between May 21 and May 22 in the northern hemisphere. This is evident from H-alpha images from Kanzelhoehe solar observatory (Austria). The on disk signatures in SOHO/EIT were faint. STEREO.B/SECCHI COR2 show a cloud ejected to the NW from the point of view of STEREO.B, this is well above the ecliptic. A B1.4 long duration flare peaked at 18:01UT on May 23. A coronal dimming and post-flare loops are visible in the neighbourhood where the filament disappeared on May 21-22. A halo CME came into view of SOHO/C3 at 19:42 UT. STEREO.B/SECCHI COR2 indicates that the cloud intersects with the ecliptic. It is a slow CME however, with an projected estimated speed of 220 km/s. The source region was not identified as a sunspot or active region. On May 23, the source region was situated near the central meridian. A coronal hole in the nothern and the southern hemisphere was visible. The central meridian was reached on May 15 by the northern one and on May 16 by the southern one. GEOMAGNETIC ACTIVITY ------------------- The co-rotating interaction region associated with the coronal hole in the northern hemisphere arrived on May 19. The Kp reached once 4, early May 20. The presence of the southern coronal hole could not be determined from ACE-data. The influence of those coronal holes was limited. The conditions became again quiet on May 21. The partial halo CME might arrive on May 26-27. --------------------------------------------------------------------------- DAILY INDICES DATE RC EISN 10CM Ak BKG M X 2010 May 17 000 000 69 009 A1.6 0 0 2010 May 18 000 000 69 008 A1.5 0 0 2010 May 19 000 000 69 011 A1.6 0 0 2010 May 20 000 000 69 016 A1.7 0 0 2010 May 21 013 009 71 005 A2.0 0 0 2010 May 22 027 013 73 004 A2.9 0 0 2010 May 23 /// 015 75 002 A2.9 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 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 # #--------------------------------------------------------------------#