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

Archive

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:Issued: 2018 Apr 24 2044 UTC
:Product: documentation at http://www.sidc.be/products/bul
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# SIDC Weekly bulletin on Solar and Geomagnetic activity             #
#--------------------------------------------------------------------#
WEEK 903 from 2018 Apr 16
SOLAR ACTIVITY
---------------
During this week solar flaring activity was very low with no C-class flares
and only 12 B-class flares reported. All reported flares originated from
the Catania sunspot group 78 (NOAA AR 2706) which rotated on the visible
side of the Sun, from behind of the East solar limb, on April 19.
There was no wide or Earth-directed CMEs observed and the solar protons
remained at the background level during the whole week. 

The equatorial coronal hole with the large extension to the southern solar
hemisphere started its transition across the central meridian in the
evening of April 15, last day of the previous week.
On the last day of this week, April 21, patchy low latitude extension of
the northern polar coronal hole reached central meridian.
GEOMAGNETIC ACTIVITY
---------------------
During first half of the week the Earth was inside of the slow solar wind
(about 300 km/s), and the interplanetary magnetic field magnitude (IMF) was
about 5 nT.
In the evening of April 19, at about 23:19 UT, the in situ observations
showed sudden increase of the IMF, solar wind speed, density and
temperature. All this indicate arrival of the shock wave that was followed
by the interaction region between the fast and slow solar wind, and later
by the fast solar wind. The solar wind speed reached its maximum value of
about 620 km/s, in the early morning of April 21. At the end of the week
solar wind speed already decreased to about 430 km/s.
During most of the week geomagnetic conditions were quiet to unsettled.
Longer intervals of negative value of the Bz component of the
interplanetary magnetic field and the fast solar wind induced disturbed
geomagnetic conditions on April 20 (NOAA reported Kp=6 and local station at
Dourbes reported K=5).
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DAILY INDICES
DATE           RC   EISN  10CM   Ak   BKG    M   X
2018 Apr 16   012    012   069   002   A1.5   0   0   
2018 Apr 17   011    011   069   004   A1.6   0   0   
2018 Apr 18   ///    000   071   006   A2.7   0   0   
2018 Apr 19   012    012   071   002   A3.7   0   0   
2018 Apr 20   015    016   073   040   A5.7   0   0   
2018 Apr 21   ///    025   077   015   A6.2   0   0   
2018 Apr 22   ///    021   076   005   A5.3   0   0   
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# 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 SUMMARY
DAY BEGIN MAX  END  LOC    XRAY OP  10CM Catania/NOAA RADIO_BURST_TYPES 
NONE
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Details

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.