:Issued: 2009 Dec 07 1347 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 466 from 2009 Nov 30
SOLAR ACTIVITY
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Solar activity was at its lowest level during the whole week.
The Earth was facing the inactive hemisphere of the Sun. Indeed,
over the last 8 Carrington rotations, almost all active regions
appeared in restricted longitude ranges, mostly 200 - 300° and also
0 - 50°. So, all recent active regions were on the far side of the
Sun during this week.
As unique event, a limb CME was observed at the West limb on Dec.3.
A small low-latitude coronal hole rotated in a geoeffective position
late in the week by Dec.5.
Also, on Dec.1st, the transition from GOES10 to GOES14 led to a
jump in the X-ray flux measurements that is only due to a difference
in the sensitivity of the instruments.
GEOMAGNETIC ACTIVITY
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The geomagnetic activity remained quiet over the entire week, with
only a brief unsettled interval on Dec.5, associated to a weak
solar wind disturbance produced by a small low-latitude coronal
hole.
The highlight of this week was an extremely quiet period from Dec.3
to Dec.5, when the solar wind parameters all reached exceptionally
low values: speed < 250km/s, density < 0.3 electron/cm3, temperature
< 20000K and magnetic field strength < 4nT. Given the vanishing
and stable dynamic pressure of the solar wind on the Earth
magnetosphere, the corresponding geomagnetic indices stayed mostly
at Kp=0 in most ground stations from Dec.1 to Dec.5.
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DAILY INDICES
DATE RC EISN 10CM Ak BKG M X
2009 Nov 30 000 000 72 002 A0.0 0 0
2009 Dec 01 000 000 72 000 A1.4 0 0
2009 Dec 02 000 000 71 001 A1.4 0 0
2009 Dec 03 000 000 72 000 A1.4 0 0
2009 Dec 04 /// 000 72 000 A1.4 0 0
2009 Dec 05 /// 000 72 004 A0.0 0 0
2009 Dec 06 /// 000 72 004 A0.0 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 #
# Fax : 32 (0) 2 373 0 224 #
# Tel.: 32 (0) 2 373 0 491 #
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# For more information, see http://www.sidc.be.
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