SIDC Weekly Bulletin

Review of past solar and geomagnetic activity.
Source SIDC (RWC-Belgium)
Frequency Weekly
Format Plain text
Mail header SIDC Weekly Bulletin
SIDC code bul


Latest issue

:Issued: 2018 Dec 04 1248 UTC
:Product: documentation at
# SIDC Weekly bulletin on Solar and Geomagnetic activity             #
WEEK 935 from 2018 Nov 26
During the first part of this week only one active region, NOAA AR 2728 (no
Catania number) was observed on the visible side of the solar disc. This
active region decayed fast and the rest of the week Sun was spotless.
Accordingly, flaring activity was extremely low this week with no C-class
flares and not even B-class flares reported. Rather large prominence,
situated close to the southern polar coronal hole, erupted at about 03:30
UT on November 30. The prominence eruption was associated with faint
partial halo CME of about 130 degrees of angular width and projected line
of the sight speed of about 200 km/s (as reported by CACTUS software). 
The CME was directed southward from the Sun-Earth line, and therefore only
glancing blow from a CME-driven shock wave might be expected at the Earth
(with low probability), on December 06. The solar protons remained at the
background level during the whole week. 

Two coronal holes were observed, on the visible side of the Sun, this week.
The first, small, negative polarity equatorial coronal hole which was
already on the western solar hemisphere in the beginning of the week, and
extended equatorial coronal hole of positive polarity which reached central
meridian on November 27.
During this week the solar wind speed was always bellow 450 m/s and the
interplanetary magnetic field magnitude was bellow 10 nT. We observed two
enhancements of the solar wind speed, first starting on November 27 and
second, more prominent one, on December 01. They were associated with small
coronal hole of positive polarity and extended equatorial coronal hole of
negative polarity, respectively. 
At about 01:00 UT on December 01, the interplanetary magnetic field
magnitude started to increase simultaneously with the density increase. At
10:00 UT also solar wind speed began to increase concurrently with the
increase of the temperature, decrease of the density and change of the phi
angle. All this indicate the arrival of the solar wind associated with the
large positive polarity equatorial coronal hole which reached central
meridian on November 27. Until the end of the week the solar wind speed
increased to about 450 km/s. 
During most of the week geomagnetic conditions were quiet to unsettled,
with only two intervals of disturbed geomagnetic conditions, local station
at Dourbes reported K=4 on December 01 and NOAA reported Kp=4 on December
DATE           RC   EISN  10CM   Ak   BKG    M   X
2018 Nov 26   ///    ///   069   001   A1.1   0   0   
2018 Nov 27   000    ///   068   007   A1.0   0   0   
2018 Nov 28   ///    ///   068   002   ////   0   0   
2018 Nov 29   000    ///   068   ///   ////   0   0   
2018 Nov 30   000    ///   068   ///   ////   0   0   
2018 Dec 01   ///    000   069   ///   ////   0   0   
2018 Dec 02   ///    000   069   ///   ////   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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This report is sent once a week, typically on a monday.
The weekly bulletin gives an overview of solar and geomagnetic activity of the past week and includes a noticeable solar events list.
Check the ISES code book for information on ISES codes.