mercoledì 30 marzo 2011

SIDC Weekly Bulletin

:Issued: 2011 Mar 29 1414 UTC
:Product: documentation at http://www.sidc.be/products/bul
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# SIDC Weekly bulletin on Solar and Geomagnetic activity            #
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WEEK 534 from 2011 Mar 21 

SOLAR ACTIVITY
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The proton flux was elevated on Mar 21 and 22. The curve passed slightly and for a very short time the proton event threshold.
The initial increase was probably linked with a back sided CME of Mar 21, 02:54UT. The Earth is magnetically connected with the source site behind the Sun. The Parker spiral has bended magnetic field lines that guide the electrically charged protons. The Earth is near such field lines along which these protons travel. This is a rare but non unprecedented event.
That same day, a long duration C-flare took place. The source region was Cat 35/AR 1176. A long duration event is an indication of an associated CME.
Since the group was at that moment located near the very east of the solar disk, the CME was not Earth directed.
This active region, 1176 had a rather complex magnetic structure: beta-gamma and  was responsible for almost all flaring activity further this week. This group exerted three moderate M-flares on Mar 23-24-25, one a day.
None of the CME's was Earth directed, except for a very slow plasma structure that left the Sun on Mar 25. Since it was very slow, it is probably overtaken by the ambient solar wind. 


GEOMAGNETIC ACTIVITY
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Mar 22-23, we had unsettled conditions probably induced by a small North-South
oriented coronal hole.

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DAILY INDICES
DATE          RC  EISN  10CM  Ak  BKG    M  X
2011 Mar 21  026    015  101  008  B3.8  0  0
2011 Mar 22  061    027  100  009  B4.5  0  0
2011 Mar 23  054    025  105  015  B3.3  1  0
2011 Mar 24  073    036  108  004  B3.2  1  0
2011 Mar 25  127    065  113  004  B4.0  1  0
2011 Mar 26  114    063  115  001  B4.3  0  0
2011 Mar 27  ///    076  117  002  B3.4  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)
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NOTICEABLE EVENTS
DAY BEGIN MAX  END  LOC    XRAY OP TENCM TYPE                      Cat NOAA NOTE
23  0203  0217 0224 S18E70 M1.4          III/2                      35  1176
24  1201  1207 1211 S16E43 M1.0 1F      V/2                        35  1176
25  2308  2322 2330 S12E26 M1.0    170  II/1,IV/1                  35  1176


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# 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                                          #
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