:Issued: 2004 Oct 04 1356 UTC
:Product: documentation at http://sidc.oma.be/products/bul
#------------------------------------------------------------------------------#
# SIDC Weekly bulletin on Solar and Geomagnetic activity #
#------------------------------------------------------------------------------#
WEEK 196 from 2004 Sep 27
SOLAR ACTIVITY
The solar activy was very low over the entire week. A few small
sunspot groups produced some B flares, while the X-ray background
remained largely at the A5 level. A few filament eruptions were
noticed, of which the most important one occured near central
meridian on Sept. 28, at 14:45UTC. This event spawned a faint
semi-halo CME that was detected in the sparse LASCO data by the
CACtus algorithm. The week ended without any other significant
solar event. This very low activity should extend at least over
the next few days.
This week, the forecasts activities were again strongly impaired
by the absence of the EIT data and fragmentary SOHO data.
GEOMAGNETIC ACTIVITY
The geomagnetic field was mostly quiet, with two unsettled periods.
The first one occured on Sept 28-29, in response to a rise of the
solar wind speed to 400km/s, associated with southward fluctuations
of the IMF. After Sept. 29, the solar wind speed decayed slowly
down to 300km/s on Oct.2, when it jumped again to about 380km/s.
Most probably, this marked the arrival at Earth of the Sept. 28
CME. The associated southward fluctuations of the IMF lasted
for the last two days of the week (Oct. 2-3). They induced unsettled
geomagnetic conditions, and temporary active levels at some high-
latitude stations, on those two days.
Given the absence of any significant active region and of any
low-latitude coronal hole, the geomagnetic field is expected to
return to quiet conditions early next weak.
DAILY INDICES
DATE RC 10CM Ak BKG M X
2004 Sep 27 022 90 /// A6.2 0 0
2004 Sep 28 023 90 /// A8.1 0 0
2004 Sep 29 048 90 /// A6.1 0 0
2004 Sep 30 058 88 /// A5.4 0 0
2004 Oct 01 058 88 /// A4.0 0 0
2004 Oct 02 039 88 /// A3.9 0 0
2004 Oct 03 061 89 /// A4.5 0 0
# RC : Sunspot index from Catania Observatory (Italy)
# 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
73,
Thomas F. Giella, KN4LF
Retired Space & Atmospheric Weather Forecaster
Plant City, FL, USA
Grid Square EL87WX
Lat & Long 27 58 33.6397 N 82 09 52.4052 W
kn4lf@arrl.net
Propagation eGroup: http://lists.contesting.com/mailman/listinfo/propagation
KN4LF Daily Solar Space Weather & Geomagnetic Data Archive:
http://www.kn4lf.com/kn4lf5.htm
KN4LF Amateur & SWL Radio History: http://www.kn4lf.com
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