:Issued: 2004 Aug 09 2114 UTC
:Product: documentation at http://sidc.oma.be/products/bul
#------------------------------------------------------------------------------#
# SIDC Weekly bulletin on Solar and Geomagnetic activity #
#------------------------------------------------------------------------------#
WEEK 188 from 2004 Aug 02
SOLAR ACTIVITY
---------------------------------
Solar activity dropped to very low levels during the past week.
At the end of last week, Catania sunspot group 82 (NOAA 0652) had
rotated over the west limb, and by Aug 02, the X-ray background
was down to below the B-level. Only only two sunspot groups were
visible: Catania 86 (NOAA 0654) in the northwest was a small
group in its decay phase, while Catania 87 (NOAA 0655) in the
southeast was slowly growing and seemed capable of C-class flares.
Indeed, on Aug 02 it generated a C3.9 flare. It later transpired
this was the largest flare of the week. It was also the only
significant event from this group. Although it still grew in
sunspot number and area and developed a clear beta-gamma
magnetic configuration, its level of activity dropped after
Aug 02 and for the next 5 days, only B-class flares were observed.
>From noon UT on Aug 03 until early on Aug 07, the solar X-ray
output did not even reach the B4 level. On Aug 06, attention shifted
to a new kid on the block: at the east limb, Catania 90 (NOAA 0656)
showed up, probably the return of Catania sunspot group 78 (NOAA
0649), which produced several X-flares on its previous rotation.
Initially, this group remained rather quiet, but early on Aug 08,
the solar X-ray output began to rise strongly and more flaring
activity developed in Catania 90, leading to 2 C-class flares
on this day.
At 08:54 on Aug 08 a splendid full halo CME was visible in the
LASCO images (another succesful detection by the CACTus software
package), but this event was determined to be backsided.
Early on Aug 02, the >10MeV proton flux was still enhanced, albeit
well below the event threshold, but during the day, it returned to
quiet levels.
GEOMAGNETIC ACTIVITY
---------------------------------
Geomagnetic conditions were bascially quiet throughout the week, except
for a small hiccup on Aug 07. At the start of the week, the solar wind
speed was at about 500 km/s and decreasing. It continued to decrease
for several more days, bottoming out just above 300 km/s on Aug 05.
It then increased a bit to 360 km/s, but the IMF remained mainly
northwards and geomagnetic conditions stayed quiet. On Aug 07,
the solar wind speed rose to more thsn 450 km/s during the second
half of the UT day, and the IMF pointed mostly southwards for most
of that day, with short periods of values below -10nT. These
conditions were probably caused by a small coronal hole. The
geomagnetic response was mixed: some geomagnetic observatories
reported K-indices up to 4 or even 5, and also NOAA\'s estimated Kp
index reached 5, but in Niemegk and Izmiran K-indices stayed at quiet
values. Early on Aug 08, the solar wind speed started a linear decline
and quiet geomagnetic conditions reigned everywhere.
---------------------------------------------------------------------------
DAILY INDICES
DATE RC 10CM Ak BKG M X
2004 Aug 02 038 85 007 A6.6 0 0
2004 Aug 03 046 88 /// A8.5 0 0
2004 Aug 04 064 85 /// A7.0 0 0
2004 Aug 05 054 89 /// B1.0 0 0
2004 Aug 06 079 91 /// B1.1 0 0
2004 Aug 07 086 95 /// B1.2 0 0
2004 Aug 08 074 105 /// B2.3 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
NONE
73,
Thomas F. Giella, KN4LF
Plant City, FL, USA
Grid Square EL87WX
Lat & Long 27 58 31 44N 82 09 51 98W
NWS Tampa Bay, FL SKYWARN Observer # HIL-249
SWFWMD Rainfall Network Observer #574 Thackery
CWOP Weather Station #CW2111
PODXS 070 PSK31 Club Member #349
KN4LF Solar Space Weather & Geomagnetic Data Archive:
http://www.kn4lf.com/kn4lf5.htm
KN4LF Daily HF/MF Radio Propagation Outlook: http://www.kn4lf.com/kn4lf6.htm
KN4LF HF/MF Radio Propagation Theory Notes: http://www.kn4lf.com/kn4lf8.htm
KN4LF Amateur & SWL Radio History: http://www.kn4lf.com
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