SIDC Weekly Bulletin

:Issued: 2019 May 20 1319 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 959 from 2019 May 13
SOLAR ACTIVITY
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There were two alpha regions on the Sun since the start of the week: NOAA
2740 and 2741. Whereas region 2740 turned into a plage soon, region 2741
kept its sunspots throughout the week, and produced one C flare. The GOES
X-ray flux background varied between about A9 and B1 level. There was an
Earth-directed CME on May 12 and 13 (the May 12 CME was associated to a
filament eruption near region 2741). The greater than 10 MeV proton flux
was at nominal levels throughout the week.
GEOMAGNETIC ACTIVITY
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The solar wind as registered by DSCOVR showed clear signs of an ICME
between about 22h UT on May 13 and 17h UT on May 14; this could be the
arrival of the CME of May 10. There are hints of a second ICME between
about 17h UT on May 14 and 1h UT on May 16, which could be due to any
combination of the CMEs of May 11, 12 and 13. Solar wind speed had a
maximum of about 570 km/s around 8h UT on May 14, while the magnitude of
the Interplanetary Magnetic Field (IMF) had a peak around 15 nT around 6h
UT. NOAA Kp reached values of 6 and 7 between 3h and 6h and between 6h and
9h UT on May 14, respectively. K Dourbes reached values of 5 and 6 during
that period. Solar wind speed varied between about 350 and 450 km/s from
May 16 onwards, and the magnitude of the IMF stayed below 10 nT.
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DAILY INDICES
DATE           RC   EISN  10CM   Ak   BKG    M   X
2019 May 13   ///    027   075   008   A8.8   0   0   
2019 May 14   024    024   074   033   A8.7   0   0   
2019 May 15   025    020   074   008   A8.9   0   0   
2019 May 16   ///    014   074   010   A8.3   0   0   
2019 May 17   013    014   072   004   A8.0   0   0   
2019 May 18   ///    013   071   004   A7.9   0   0   
2019 May 19   ///    000   068   004   A7.3   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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