martedì 6 luglio 2010

SIDC Weekly Bulletin

:Issued: 2010 Jul 06 1057 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 496 from 2010 Jun 28 

SOLAR ACTIVITY
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Solar activity was quiet throughout the week. Two sunspot groups were reported. Catania sunspot group 93 (NOAA AR 1084) was visible during the whole week, and Catania sunspot group 94 (NOAA AR 1085) was visible on June 29-30. The strongest flare reported during the week was the B1.4 flare peaking at 05:01 UT on June 29.

A large low-latitude extension of the northern polar coronal hole passed the solar central meridian on June 28 - July 1. The fast solar wind stream emanating from this coronal hole arrived at the Earth early on June 30 (see below).

GEOMAGNETIC ACTIVITY
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In the beginning of the week the Earth was located in the trailing part of the fast solar wind stream. The interplanetary magnetic field (IMF) magnitude was at the average level, so no geomagnetic disturbance was produced. The fast stream originated from another low-latitude extension of the polar coronal hole in the northern hemisphere that passed the solar central meridian last week.

Late on June 29, an interaction region between slow and fast solar wind flows was detected by ACE, followed by the fast stream (solar wind speed reached 700 km/s). The fast stream was emanating from the low-latitude extension of the polar coronal hole in the northern hemisphere (see above). No interplanetary sector boundary crossing occurred as both streams originated from solar regions of the same magnetic polarity. The southward IMF component reached 9 nT, although the field direction was oscillating. On June 29-30, disturbed geomagnetic conditions up to the minor storm level (K = 5) were reported by NOAA, and up to the active level (K = 4) by IZMIRAN and Dourbes.

The fast stream continued throughout the rest of the week. The IMF magnitude was weak to average, so only isolated intervals of active geomagnetic conditions (K = 4) were reported by NOAA on July 1 and by IZMIRAN on July 2 and 3.

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DAILY INDICES
DATE           RC   EISN  10CM   Ak   BKG    M   X
2010 Jun 28   011    007   74   010   A4.5   0   0
2010 Jun 29   025    015   74   014   A4.4   0   0
2010 Jun 30   011    007   74   018   A4.3   0   0
2010 Jul 01   011    007   73   015   A4.4   0   0
2010 Jul 02   011    007   73   010   A4.4   0   0
2010 Jul 03   011    008   72   007   A4.3   0   0
2010 Jul 04   ///    008   72   005   A4.2   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


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# Solar Influences Data analysis Center - RWC Belgium                #
# Royal Observatory of Belgium                                       #
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